Polymers

Abstract

A nitrogen containing compound, wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or ea

Description

Silicone compounds, such as polydimethylsiloxane, functionalised polydimethylsiloxanes, organosilicones, and related compounds are used widely in a range of applications and products. They may be provided in concentrate compositions, either for direct use or for later dilution priorto use. However, high concentrations of silicone compounds can cause concentrate compositions to be highly viscous and difficult to pour or pump. Furthermore, high concentrations of the silicone compound can cause concentrate compositions to be unstable when stored for extended periods of time, especially when the silicone compound is poorly soluble or poorly miscible with a diluent comprised in the concentrate composition. There are a number of disadvantages associated with the use of such silicone compounds, including their low biodegradability, which has led to environmental concerns. It is thus an object of the invention to provide an alternative to silicone compounds that can be used in a wide range of applications and uses. It is another object of the invention to provide alternatives to silicone compounds that are more biodegradable whilst having equal or improved properties. It is another object of the invention to improve the stability and / or flowability of concentrate compositions comprising such compounds. Summary of the Invention According to aspects of the present invention, there is provided a nitrogen containing compound, method and concentrate composition as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and from the description which follows. The inventors have identified that certain nitrogen containing compounds have properties that are at least comparable to those provided by known silicone compounds, whilst also being more biodegradable. According to a first aspect of the invention, there is provided a nitrogen containing compound, wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. According to a second aspect of the invention, there is provided a concentrate composition comprising one or more nitrogen containing compounds and optionally at least one solvent, wherein the concentrate composition comprises at least 20 wt% of the one or more nitrogen containing compounds, and wherein the or each nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. According to a third aspect of the invention, there is provided a use of a surfactant to emulsify at least one nitrogen containing compound in an aqueous concentrate composition, wherein the aqueous concentrate composition comprises at least 20 wt% of the one or more nitrogen containing compounds, and wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. According to a fourth aspect of the invention, there is provided a method of emulsifying at least one nitrogen containing compound in an aqueous composition to make an aqueous concentrate composition, wherein the aqueous concentrate composition comprises at least 20 wt% of the one or more nitrogen containing compounds, the method comprising admixing a surfactant with the nitrogen containing compound in an aqueous composition, wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. Other features of the invention will be apparent from the dependent claims, and from the description which follows. Features described in relation to the second, third and fourth aspects may have any of the suitable features and advantages described in relation to the first and second aspects. Detailed Description of the Invention Unless otherwise stated, the following terms used in the specification and claims have the meanings set out below. The terms “alkyl” and “alkylene” include both straight and branched chain alkyl and alkylene groups respectively unless otherwise stated. References to individual alkyl groups such as “propyl” are specific for the straight chain version only and references to individual branched chain alkyl groups such as “isopropyl” are specific for the branched chain version only. For example, “C3-30 alkyl” includes C6-24 alkyl, Ce-s alkyl, propyl, isopropyl and t-butyl. The term “alkenyl” includes both straight and branched chain alkenyl groups. References to individual alkenyl groups such as “propenyl” are specific for the straight chain version only and references to individual branched chain alkenyl groups such as “isopropenyl” are specific for the branched chain version only. For example, “C3-30 alkenyl” includes C6-24 alkenyl, Ce-s alkenyl, propenyl and isopropenyl. Herein C3-30 means a group having from 3 to 30 carbons atoms therein, for example having 3, 4, 5 etc up to 30 carbon atoms. The term "hydrocarbyl" is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. As used in the specification and the appended claims, the singular forms "a", "an," and "the" include both singular and plural referents unless the context clearly dictates otherwise. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of other components. The term “consisting essentially of’ or “consists essentially of’ means including the components specified but excluding other components except for components added for a purpose other than achieving the technical effect of the invention. The term “consisting of’ or “consists of’ means including the components specified but excluding other components. Whenever appropriate, depending upon the context, the use of the term “comprises” or “comprising” may also be taken to include the meaning “consists essentially of’ or “consisting essentially of’, and also may also be taken to include the meaning “consists of’ or “consisting of’. As used herein, unless otherwise expressly specified, all numbers such as those expressing values, ranges, amounts of percentages may be read as if prefaced by the word “about”, even if the term does not expressly appear. The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1,2,3,4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.70 and 3.80, when referring to, for example, measurements). The recitation of end points also includes the end point values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein. The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each exemplary aspect of the invention, as set out herein are also applicable to any other aspects or exemplary aspects of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each aspect or embodiment of the invention as interchangeable and combinable between different aspects of the invention. As used herein, the term "and / or," when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a list is described as comprising group A, B, and / or C, the list can comprise A alone; B alone; C alone; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination. The term “monomer” is used herein to refer to a compound comprising at least one polymerisable functional group. As reported herein, the number average molecular weight was determined by gel permeation chromatography using a polystyrene standard according to ASTM D6579-11 (“Standard Practice for Molecular Weight Averages and Molecular Weight Distribution of Hydrocarbon, Rosin and Terpene Resins by Size Exclusion Chromatography”. UV detector; 254 nm, solvent: unstabilised THF, retention time marker: toluene, sample concentration: 2mg / ml). According to a first aspect of the invention, there is provided a nitrogen containing compound, wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. Suitable features of the first aspect will now be described. The nitrogen containing compound may be a polymer, a non-polymer, or a mixture of polymers and non-polymers. The nitrogen containing compound is preferably a polymer. The reactants are preferably monomers. The one or more first reactants are preferably one or more first monomers, the one or more second reactants are preferably one or more second monomers, and the polyfunctional reactant is preferably a polyfunctional monomer having at least one reactive amino group. According to the first aspect of the invention, there may be provided a polymer, wherein the polymer is the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is a polycarboxylic acid or a reactive equivalent thereof and the or each second monomer is a polyfunctional monomer having at least one reactive amino group. The embodiments described herein relating to ‘polymers’ may equally be applied to nitrogen containing compounds as defined herein, and the embodiments described herein relating to ‘monomers’ may equally be applied to reactants as defined herein. However, polymers and monomers are preferred. The polymer that is a preferred embodiment of the first aspect is the reaction product of monomers comprising one or more first monomers and one or more second monomers as defined herein. In other words, the polymer may be obtainable or obtained by polymerising monomers comprising one or more first monomers and one or more second monomers as defined herein. Thus, the reaction product is a polymer comprising repeat units derived from the one or more first monomers and repeat units derived from the one or more second monomers as defined herein. The polymer that is a preferred embodiment of the first aspect may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers as defined herein. In other words, the polymer may be obtainable or obtained by polymerising monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers as defined herein. Thus, the reaction product may be a polymer consisting essentially of or consisting of repeat units derived from the one or more first monomers and the one or more second monomers as defined herein. Typically, the polymer that is the reaction product of the monomers defined herein is a polyamide. The first and second monomers may be reacted in any suitable molar ratio to make the polymer, as would be appreciated by a person skilled in the art. Thus repeat units in the polymer derived from the first and second monomers may be present in the polymer in any suitable molar ratio and in any suitable arrangement. The first and second monomers may be reacted in a molar ratio of from 1:10 to 10:1, preferably from 1:6 to 6:1, for example from 1:3 to 3:1. Ratios refer to the total amounts of first monomers or second monomers if more than one first monomer or second monomer is present. The firstand second monomers may be reacted in a molar ratio of from 1:1.5 to 1.5:1, such as a molar ratio of 1:1. The polymer may be prepared by any suitable method, as would be known to persons skilled in the art. Suitably, the polymer is not in a solid form. For example, the polymer is preferably in the form of a liquid or gel, preferably a liquid. Suitably, the polymer herein that is the reaction product of monomers comprising one or more first monomers and one or more second monomers is substantially free or free of cross-linking. References herein to a reaction product of monomers comprising the first and second monomers are intended to refer to a product of the reaction of monomers comprising the first and second monomers conducted in any suitable manner. For example, the reaction may occur between the first and second monomers in the absence of other monomer(s) or may occur in the presence of other monomer(s). The or each of the one or more first monomers used to make the polymer is a polycarboxylic acid or a reactive equivalent thereof. By the term “reactive equivalent”, we mean a compound that results in the same reaction product as the corresponding polycarboxylic acid. Suitable reactive equivalents include anhydrides (preferably cyclic anhydrides), acid chlorides and esters of polycarboxylic acids (preferably of the polycarboxylic acids described herein). Mixtures of two or more different first monomers (i.e. different polycarboxylic acids or reactive equivalents thereof, such as different polycarboxylic acids, different anhydrides, acid chlorides, or esters thereof, or for example a cyclic anhydride and a polycarboxylic acid or an acid chloride or ester thereof thereof) may be used to make the polymer. Any suitable polycarboxylic acid and / or reactive equivalent thereof may be used to make the polymer, as would be understood by the person skilled in the art. The or each of the one or more first monomers may comprise one or more cyclic anhydrides. The or each of the one or more first monomers may consist essentially of or consist of one or more cyclic anhydrides. By the term cyclic anhydride we mean a compound (or monomer) that comprises at least one anhydride group that is contained within a ring structure. For example, the ring structure that contains the anhydride group may comprise from 4 to 8 atoms, which atoms are typically carbon and oxygen. The ring structure that contains the anhydride group may be saturated or partially unsaturated. The cyclic anhydride compound may typically comprise more than 8 atoms. For example, suitable cyclic anhydrides may include one or more of an anhydride of formula (I), of formula (II) and of formula (III): wherein in formula (I) R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group, or R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; in formula (II) R3 and R4 are each independently selected from hydrogen, an alkyl group and an alkenyl group, or R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; and in formula (III) X is CR9R10, O, S, or NR11; R5, R6, R7, R8, R9, R10, and R11 are each independently selected from hydrogen, an alkyl group and an alkenyl group, and / or any of R5, R6, R7, R8, R9, R10, and R11 together with the atoms to which they are attached represent an optionally substituted cyclic group. Cyclic anhydrides of formula (I) are preferred. X may suitably be CR9R10, O, or S. Preferably, X is CR9R10. When any of R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, and R11 represents an alkyl group or an alkenyl group, the or each alkyl or alkenyl group may be branched or unbranched. The or each alkyl group may contain from 1 to 30 carbon atoms and the or each alkenyl group may contain from 2 to 30 carbon atoms. Preferably, each alkyl or alkenyl group may contain 6 or more carbon atoms. For example, the or each alkyl or alkenyl group may contain from 6 to 30, such as from 8 to 24, carbon atoms (i.e. may be a Ce-30, such as a Ca-24, alkyl or alkenyl group). When any of R1 and R2, or R3 and R4, orR5, R6, R7, R8, R9, and R10 represents an alkenyl group, the alkenyl group may be a branched alkenyl group, such as a tetrapropenyl group or a polyisobutenyl group. When any of R1 and R2, or R3 and R4, orR5, R6, R7, R8, R9, and R10 represents an alkenyl group, the alkenyl group may be a polyisobutenyl group. The polyisobutenyl group (when present) suitably has a number average molecular weight of from 100 to 2000, preferably from 100 to 1000, for example 260 or 550. The cyclic anhydride may be a polyisobutenyl succinic anhydride, for example wherein the polyisobutenyl group has a number average molecular weight of 260 or 550. When any of R1 and R2, or R3 and R4, orR5, R6, R7, R8, R9, and R10 represents an alkenyl group, the alkenyl group may be derived from a terminal olefin or an internal olefin. For example, the cyclic anhydride monomer may be an alkenyl substituted succinic anhydride prepared by the reaction of an alkene with maleic anhydride, wherein the alkene is a terminal olefin or an internal olefin. In some embodiments the alkenyl group may be derived from a terminal olefin. The term terminal olefin is used to refer to alkene compounds having a predominantly terminal double bond. Such compounds are also commonly described as terminal alkenes. Terminal double bonds terminate in a =CH2 group and may either be at the a-position or may be vinylidene groups. The terminal olefin is preferably an a-olefin. Examples of suitable terminal olefins include C15-18 terminal olefin and Cie terminal olefin. In some preferred embodiments the alkenyl group is derived from an internal olefin. The term internal olefin is used to refer to alkene compounds in which the alkene groups are predominantly not terminal. Examples of suitable internal olefins include C12 internal olefin, C15-18 internal olefin, C16 internal olefin and C18 internal olefin. The internal olefin is a p or higher olefin, such as a p-olefin. Internal olefins are sometimes known as isomerised olefins and may be prepared by isomerisation of an a-olefin. Typically, terminal olefins and internal olefins may be provided as a mixture of isomers. Suitably at least 70 mol%, such as at least 80 mol%, preferably at least 90 mol%, for example at least 95 mol% of the double bonds in terminal olefins are terminal double bonds. Suitably at least 70 mol%, such as at least 80 mol%, preferably at least 90 mol%, for example at least 95 mol% of the terminal double bonds in the terminal olefins are at the a-position (i.e. they are a-alkene groups). Suitably at least 70 mol%, such as at least 80 mol%, preferably at least 90 mol%, for example at least 95 mol% of the double bonds in internal olefins are non-terminal double bonds. Suitably, one of R1 and R2, R3 and R4, orR5, R6, R7, R8, R9, R10, and R11 may be an alkyl group or an alkenyl group (such as an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and the other (or others) may be hydrogen. Examples of cyclic anhydride monomers of the formula (I), (II) or (III) wherein any of R1 and R2, R3 and R4, orR5, R6, R7, R8, R9, R10, and R11 represents hydrogen or a C6-30, such as a Cs-24, branched or unbranched alkyl or alkenyl group include succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), tetrapropenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, nonenyl succinic anhydride, C20-24 alkenyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, C16 terminal olefin-derived alkenyl succinic anhydride, maleic anhydride and glutaric anhydride. The cyclic anhydride monomers of the formula (I), (II) or (III) wherein any of R1 and R2, R3 and R4, orR5, R6, R7, R8, R9, R10, and R11 represents hydrogen or a C6-30, such as a Cs-24, branched or unbranched alkyl or alkenyl group may be selected from succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), tetrapropenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, nonenyl succinic anhydride, C20-24 alkenyl succinic anhydride, maleic anhydride and glutaric anhydride. The cyclic anhydride monomers are preferably selected from C15-18 internal olefin-derived alkenyl succinic anhydride, Cie internal olefin-derived alkenyl succinic anhydride, and Cie terminal olefin-derived alkenyl succinic anhydride. When any of R1 and R2, or R3 and R4, orR5, R6, R7, R8, R9, R10, and R11, together with the atoms to which they are attached represent an optionally substituted cyclic group, the cyclic group so formed may be mono or polycyclic (preferably mono or bicyclic) and may be aromatic or nonaromatic. Examples of aromatic groups that may be so formed include benzene and naphthalene. Examples of non-aromatic groups that may be so formed include cyclopentane, cyclohexane, and cyclooctane. Any of R5, R6, R7, R8, R9, R10, and R11 together with the atoms to which they are attached may represent an optionally substituted cyclic group. Any of R5, R6, R7, R8, R9, R10, and R11 not representing a cyclic group are independently selected from hydrogen, an alkyl group and an alkenyl group as described herein. Two, three, four, five, or six of R5, R6, R7, R8, R9, R10, and R11 together with the atoms to which they are attached may represent an optionally substituted cyclic group. Suitably at least R5 and R7, or R5 and R9, or R5 and R11, or R7 and R9, or R7 and R11, or R5, R7 and R9, or R5, R7 and R11 together with the atoms to which they are attached may represent an optionally substituted cyclic group. For the avoidance of doubt, when any of R5, R6, R7, R8, R9, and R10 together with the atoms to which they are attached represent an optionally substituted cyclic group, one or more of R5, R6, R7, R8, R9, and R10 may contribute to one or more double bonds (for example, aromaticity) in the cyclic group. For example, R8 and R10 may together form a carbon-carbon double bond, which may form part of an aromatic cyclic group. The optionally substituted cyclic group represented by R1 and R2, or R3 and R4, or any of R5, R6, R7, R8, R9, R10, and R11, together with the atoms to which they are attached (when present) may be optionally substituted with any suitable substituent(s), such as for example one or more substituents independently selected from alkyl (for example C1-30, preferably C1-24, such as C1-4 or Ca-24, alkyl), alkenyl (for example C2-30, preferably C2-24, such as C2-4 or Ca-24, alkenyl), alkoxy (for example C1-30, preferably C1-24, such as C1-4 or Ca-24, alkoxy), alkenyloxy (for example C2-30, preferably C2-24, such as C2-4 or Ca-24, alkenyloxy), carboxy, alkoxy-carbonyl (for example C1-30, preferably C1-24, such as C1-4 or Ca-24, alkoxy-carbonyl), alkenyloxy-carbonyl (for example C2-30, preferably C2-24, such as C2-4 or Ca-24, alkenyloxy-carbonyl), hydroxy, halo (for example chloro or fluoro), nitro and cyano groups. The optionally substituted cyclic group represented by R1 and R2, or R3 and R4, or any of R5, R6, R7, R8, R9, R10, and R11, together with the atoms to which they are attached (when present) may alternatively be substituted by groups which form a further cyclic anhydride group. An example of such a cyclic anhydride is pyromellitic dianhydride. However, in some embodiments the cyclic anhydride monomers of the formula (I), (II) or (III) contain a single (i.e. only one) anhydride group. In such embodiments, the optionally substituted cyclic group represented by R1 and R2, or R3 and R4, or any of R5, R6, R7, R8, R9, R10, and R11, together with the atoms to which they are attached (when present) may not be substituted by a further cyclic anhydride group. Examples of suitable cyclic anhydrides of formula (I) in which R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group include optionally substituted 1,2-cyclohexanedicarboxylic anhydride and 1,3-cyclopentanedicarboxylic anhydride. 1,2-Cyclohexanedicarboxylic anhydride is preferred. Examples of suitable anhydrides of formula (II) in which R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group include optionally substituted phthalic anhydride, pyromellitic dianhydride, 1,2-naphthalic anhydride and 2,3-naphthalic anhydride. Examples of a substituted phthalic anhydride may include 1,2,4-benzenetricarboxylic anhydride, and 6-((octadec-9-en-1-yloxy)carbonyl)-1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid. Examples of suitable anhydrides of formula (III) in which any of R5, R6, R7, R8, R9, R10, and R11 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group include optionally substituted 1,8-naphthalic anhydride and homophthalic anhydride. Preferred cyclic anhydrides include one or more cyclic anhydrides of formula (I) wherein R1 and R2 are each independently selected from hydrogen and a Cs-3o, such as a Cs-24, alkyl or alkenyl group, or wherein R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; or of formula (II) wherein R3 and R4 are each independently selected from hydrogen and a Cs-3o, such as a Cs-24, alkyl or alkenyl group, or wherein R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; or of formula (III) wherein X is CR9R10, O, or S and R5, R6, R7, R8, R9, and R10 are each independently selected from hydrogen and a Cs-3o, such as a Cs-24, an alkyl group or alkenyl group, and / or wherein any of R5, R6, R7, R8, R9, and R10 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group. More preferred cyclic anhydrides include one or more cyclic anhydrides of formula (I) wherein R1 and R2 are each independently selected from hydrogen and a Cs-3o, such as a Cs-24, alkenyl group, or wherein R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; or of formula (II) wherein R3 and R4 are both hydrogen, or wherein R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; or of formula (III) wherein X is CR9R10, O, or S and R5, R6, R7, R8, R9, and R10are each hydrogen, and / or wherein any of R5, R6, R7, R8, R9, and R10 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group. Preferably, at least one of the first monomers is a cyclic anhydride of formula (I), (II) or (III) wherein at least one of R1 and R2, or at least one of R3 and R4, or at least one of R5, R6, R7, R8, R9, R10, and R11, is a Ce-3o, such as a Cs-24, alkyl or alkenyl (more preferably alkenyl) group (such as an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin). Preferably, at least one of the first monomers is a cyclic anhydride of formula (I), (II) or (III) wherein at least one of R1 and R2, or at least one of R3 and R4, or at least one of R5, R6, R7, R8, R9, R10, and R11, is a Cs-3o, such as a Cs-24, alkyl or alkenyl (more preferably alkenyl) group (such as an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and the other (or others) is (or are) hydrogen. For example, the cyclic anhydride may be an anhydride of formula (I) wherein R1 and R2 are both hydrogen (i.e. the cyclic anhydride may be succinic anhydride). For example, the cyclic anhydride may be an anhydride of formula (II) wherein R3 and R4 are both hydrogen (i.e. the cyclic anhydride may be maleic anhydride). For example, the cyclic anhydride may be an anhydride of formula (III) in which X is CR9R10 and R5, R6, R7, R8, R9, and R10 each represent hydrogen (i.e. the cyclic anhydride may be glutaric anhydride). For example, the cyclic anhydride may be an anhydride of formula (III) in which X is O and R5, R6, R7, and R8 each represent hydrogen (i.e. the cyclic anhydride may be diglycolic anhydride). For example, the cyclic anhydride may be an anhydride of formula (III) in which X is S and R5, R6, R7, and R8 each represent hydrogen (i.e. the cyclic anhydride may be thiodiglycolic anhydride). For example, the or each cyclic anhydride may be an anhydride of formula (I) wherein R1 and R2 are both hydrogen or wherein one of R1 and R2 is an alkyl or alkenyl group (such as an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and the other of R1 and R2 is hydrogen. For example, the or each cyclic anhydride may be an anhydride of formula (I) wherein R1 and R2 are both hydrogen or wherein one of R1 and R2 is a Ce-30, such as a Cs-24, alkyl or alkenyl (more preferably alkenyl) group (such as an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and the other of R1 and R2 is hydrogen. Examples of such cyclic anhydride compounds include succinic anhydride, C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, and C16 terminal olefin-derived alkenyl succinic anhydride. The cyclic anhydride compound may be selected from succinic anhydride, C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride and octenyl succinic anhydride. The cyclic anhydride compound is preferably selected from C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, and C16 terminal olefin-derived alkenyl succinic anhydride. Preferably, the or each cyclic anhydride may be an anhydride of formula (I) wherein one of R1 and R2 is an alkenyl group, such as a C6-30 (preferably C8-24) alkenyl group (such as a C6-30 (preferably C8-24) alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin), and the other of R1 and R2 is hydrogen. Examples of such cyclic anhydride compounds include C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, and C16 terminal olefin-derived alkenyl succinic anhydride. The cyclic anhydride compound may be selected from C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride and octenyl succinic anhydride. The cyclic anhydride compound is preferably selected from C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, and C16 terminal olefin-derived alkenyl succinic anhydride. Preferably, the or each cyclic anhydride may be dodecenyl succinic anhydride, such as (2-dodecen-1-yl)succinic anhydride. The or each cyclic anhydride may be an anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other of R1 and R2 is a polyisobutenyl group, for example wherein the polyisobutenyl group suitably has a number average molecular weight of from 100 to 2000, preferably from 100 to 1000, for example 260 or 550. Preferably, the or each cyclic anhydride may be a cyclic anhydride of formula (I) or (II) wherein R1 and R2, or R3 and R4, together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is an aromatic or a non-aromatic group and is mono or polycyclic. Preferably, the or each cyclic anhydride may be an anhydride of formula (I) wherein R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is a non-aromatic (for example saturated) mono or bicyclic group. More preferably, the or each cyclic anhydride may be a cyclic anhydride of formula (I) wherein R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is a non-aromatic (for example saturated) monocyclic group, such as a cyclohexane group. Preferably, the or each cyclic anhydride may be an anhydride of formula (II) wherein R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is an aromatic mono or bicyclic group, such as a benzene or naphthalene group. More preferably, the or each cyclic anhydride may be a cyclic anhydride of formula (II) wherein R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is an aromatic monocyclic group, such as a benzene group. Preferably, the or each cyclic anhydride may be an anhydride of formula (III) wherein X is CR9R10 and R5, R6, R7, R8, R9, and R10 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is an aromatic bicyclic group, such as a naphthalene group; or R7 and R8 are hydrogen and R5, R6, R9 and R10 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is an aromatic monocyclic group, such as a benzene group. More preferably, the or each cyclic anhydride may be an anhydride of formula (III) wherein X is CR9R10 and R5, R6, R7, R8, R9, and R10 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group, wherein the cyclic group is an aromatic bicyclic group, such as a naphthalene group. When the cyclic anhydride is an anhydride of formula (I) wherein R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclohexane group, the cyclic anhydride may be of the formula (IA): wherein n1 is an integer from 0 to 4 and each R12 (when present) is independently selected from alkyl (for example C1-30, preferably C1-24, such as C1-4, alkyl), alkenyl (for example C2-30, preferably C2-24, such as C2-4, alkenyl), alkoxy (for example C1-30, preferably C1-24, such as C1-4, alkoxy), alkenyloxy (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy), carboxy, alkoxy-carbonyl (for example C1-30, preferably C1-24, such as C1-4, alkoxy-carbonyl), alkenyloxycarbonyl (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy-carbonyl), hydroxy, halo (for example chloro or fluoro), nitro and cyano groups, or when n1 is 2 the two R12 groups may represent a further cyclic anhydride group (such as a further succinic anhydride group). Examples of suitable succinic anhydrides of formula (IA) include 1,2-cyclohexanedicarboxylic anhydride. When the cyclic anhydride is an anhydride of formula (II) wherein R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted benzene group, the cyclic anhydride may be of the formula (IIA): wherein n2 is an integer from 0 to 4 and each R13 (when present) is independently selected from alkyl (for example C1-30, preferably C1-24, such as C1-4, alkyl), alkenyl (for example C2-30, preferably C2-24, such as C2-4, alkenyl), alkoxy (for example C1-30, preferably C1-24, such as C1-4, alkoxy), alkenyloxy (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy), carboxy, alkoxy-carbonyl (for example C1-30, preferably C1-24, such as C1-4, alkoxy-carbonyl), alkenyloxycarbonyl (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy-carbonyl), hydroxy, halo (for example chloro or fluoro), nitro and cyano groups, or when n2 is 2 the two R13 groups may represent a further cyclic anhydride group (such as a further succinic anhydride group). In some embodiments, the cyclic anhydride of formula (IIA) contains a single (i.e. only one) anhydride group. In such embodiments, two R13 groups may not represent a further cyclic anhydride group. When R13 represents a alkoxy-carbonyl (for example C1-30, preferably Ca-24, alkoxy-carbonyl) or alkenyloxy-carbonyl (for example C2-30, preferably Ca-24, alkenyloxy-carbonyl), substituent, the alkoxy-carbonyl or alkenyloxy-carbonyl group may be of the formula -C(O)OR13 wherein R13 is a Ci-30, preferably Ca-24, alkyl group or a C2-30, preferably Ca-24, alkenyl group. Suitably R13’ may represent an oleyl group. Examples of suitable succinic anhydrides of formula (HA) include phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-naphthalic anhydride and 2,3-naphthalic anhydride, and 6-((octadec-9-en-1-yloxy)carbonyl)-1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid. When the cyclic anhydride is an anhydride of formula (III) wherein X is CR9R10 and R5, R6, R7, R8, R9, and R10 together with the carbon atoms to which they are attached representan optionally substituted naphthalene group, the cyclic anhydride may be of the formula (IIIA): (R15)n4 (IIIA) wherein each of n3 and n4 is independently an integer from 0 to 3 and each of R14 and R15 (when present) is independently selected from alkyl (for example C1-30, preferably C1-24, such as C1-4, alkyl), alkenyl (for example C2-30, preferably C2-24, such as C2-4, alkenyl), alkoxy (for example Ci-30, preferably C1-24, such as C1-4, alkoxy), alkenyloxy (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy), carboxy, alkoxy-carbonyl (for example C1-30, preferably C1-24, such as C1-4, alkoxy-carbonyl), alkenyloxy-carbonyl (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy-carbonyl), hydroxy, halo (for example chloro or fluoro), nitro and cyano groups. Examples of suitable succinic anhydrides of formula (IIIA) include 1,8-naphthalic anhydride. When the cyclic anhydride is an anhydride of formula (III) wherein X is CR9R10, R7 and R8 are hydrogen and R5, R6, R9 and R10 together with the carbon atoms to which they are attached represent an optionally substituted benzene group, the cyclic anhydride may be of the formula (IIIB): wherein n5 is an integer from 0 to 4 and each R16 (when present) is independently selected from alkyl (for example C1-30, preferably C1-24, such as C1-4, alkyl), alkenyl (for example C2-30, preferably C2-24, such as C2-4, alkenyl), alkoxy (for example C1-30, preferably C1-24, such as C1-4, alkoxy), alkenyloxy (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy), carboxy, alkoxy-carbonyl (for example C1-30, preferably C1-24, such as C1-4, alkoxy-carbonyl), alkenyloxycarbonyl (for example C2-30, preferably C2-24, such as C2-4, alkenyloxy-carbonyl), hydroxy, halo (for example chloro or fluoro), nitro and cyano groups. Examples of suitable succinic anhydrides of formula (IIIB) include homophthalic anhydride. Suitably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, glutaric anhydride, a C6-30 alkenyl succinic anhydride such as C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, octadecyl succinic anhydride, octyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, or C16 terminal olefinderived alkenyl succinic anhydride a branched alkenyl succinic anhydride such as tetrapropenyl succinic anhydride or polyisobutenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride and homophthalic anhydride. Suitably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, glutaric anhydride, a C6-30 alkenyl succinic anhydride such as C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, octadecyl succinic anhydride, or octyl succinic anhydride, a branched alkenyl succinic anhydride such as tetrapropenyl succinic anhydride or polyisobutenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride and homophthalic anhydride. Suitably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, glutaric anhydride, a Ce-30 alkenyl succinic anhydride such as C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, octadecyl succinic anhydride, or octyl succinic anhydride, and a branched alkenyl succinic anhydride such as tetrapropenyl succinic anhydride or polyisobutenyl succinic anhydride. Suitably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, glutaric anhydride, and a C6-30 alkenyl succinic anhydride such as C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, octadecyl succinic anhydride, or octyl succinic anhydride. Suitably, the or each cyclic anhydride may be selected from one or more of phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride and homophthalic anhydride. Suitably, the or each cyclic anhydride may be selected from one or more of phthalic anhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride and homophthalic anhydride. More suitably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride, homophthalic anhydride and glutaric anhydride. More suitably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, and glutaric anhydride. Preferably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride and 1,8-naphthalic anhydride. Preferably, the or each cyclic anhydride may be selected from one or more of succinic anhydride, maleic anhydride, C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, and octenyl succinic anhydride. Preferably, the or each cyclic anhydride may be selected from one or more of phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride and 1,8-naphthalic anhydride. Preferably, the or each cyclic anhydride may be selected from one or more of C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, and C16 terminal olefin-derived alkenyl succinic anhydride. The cyclic anhydride compounds discussed herein may be commercially available or may be prepared using procedures well known in the art. For example, alkenyl substituted succinic anhydrides are typically prepared by the reaction of an alkene with maleic anhydride. Preferably, the or each cyclic anhydride may be independently selected from a C6-30 alkyl or alkenyl substituted succinic anhydride, phthalic anhydride and pyromellitic dianhydride. Preferably, the or each cyclic anhydride may be independently selected from a C6-30 alkyl or alkenyl substituted succinic anhydride. Preferably, the or each cyclic anhydride may be independently selected from a C6-30 alkenyl substituted succinic anhydride wherein the alkenyl group is derived from a terminal olefin or an internal olefin, preferably an internal olefin. Preferably, the or each cyclic anhydride may be independently selected from (2-dodecen-1-yl)succinic anhydride, nonenyl succinic anhydride, octadecenyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, C16 terminal olefin-derived alkenyl succinic anhydride, tetrapropenyl succinic anhydride, phthalic anhydride and pyromellitic dianhydride. Preferably, the or each cyclic anhydride may be independently selected from (2-dodecen-1-yl)succinic anhydride, nonenyl succinic anhydride, octadecenyl succinic anhydride, phthalic anhydride and pyromellitic dianhydride. Preferably, the or each cyclic anhydride may be independently selected from (2-dodecen-1-yl)succinic anhydride, nonenyl succinic anhydride, and octadecenyl succinic anhydride. Preferably, the or each cyclic anhydride may be independently selected from phthalic anhydride and pyromellitic dianhydride. The or each of the one or more first monomers may comprise one or more polycarboxylic acids or acid chloride or esters thereof. The or each of the one or more first monomers may consist essentially of or consist of one or more polycarboxylic acids or acid chloride or esters thereof. The polycarboxylic acid may comprise two or more carboxylic acid groups, such as two or three carboxylic acid groups. Preferred polycarboxylic acids are dicarboxylic acids. The polycarboxylic acid may be aliphatic or aromatic. The aliphatic polycarboxylic acid may be cycloaliphatic. The aliphatic polycarboxylic acid may be saturated or unsaturated. By the term “unsaturated” we mean that the polycarboxylic acid comprises one or more carbon-carbon double bonds. The polycarboxylic acid may comprise one or more heteroatoms other than the oxygen atoms in the carboxylic acid groups. By the term “heteroatoms” we mean atoms other than carbon or hydrogen, such as oxygen, nitrogen and sulfur atoms. For example, the polycarboxylic acid may comprise one or more moieties selected from hydroxy groups, amino groups, ether groups, and / or thioether groups. The polycarboxylic acid may be of the formula HOOC(CR2)nCOOH, wherein n is from 0 to 30; and each R is independently hydrogen ora substituent; and / or two R groups on the same carbon atom may be taken together to form a methylene (=CH2) group; and / or when n is two or more, two R groups on adjacent carbon atoms may be taken together to form a double bond. n is suitably from 1 to 20, preferably from 2 to 16, more preferably from 2 to 12, for example from 2 to 10. Each (CR2) group can be the same or different. Unless otherwise specified, the terms “each R”, “R groups” and the like are intended to refer to all instances of the “R” group in the formula HOOC(CR2)nCOOH, Each R may be hydrogen. Alternatively, one or two R groups may be a substituent and the remaining R groups may be hydrogen. Any suitable substituent may be used as R. The substituent may be a hydrocarbyl group or a heteroatom-containing group. Examples of suitable substituents include hydroxy groups, amino groups, carboxyl groups, alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and alkaryl groups, wherein the alkyl groups, alkenyl groups, aryl groups, aralkyl groups, and alkaryl groups are optionally substituted with one or more of a hydroxy group, an amino group, and / or a carboxyl group. One or two of the R groups may be a hydroxy group. Another of the R groups may optionally be a carboxyl group or a carboxyl-substituted methyl group, and the remaining R groups are suitably hydrogen. Suitably, one or two of the R groups may be a hydroxy group, another of the R groups may be a carboxyl group or a carboxyl-substituted methyl group, and the remaining R groups may be hydrogen; or one ortwo of the R groups may be a hydroxy group and the remaining R groups may be hydrogen. The polycarboxylic acid may be malic acid, tartaric acid, or citric acid. One or two R groups may be an alkyl or alkenyl group. Preferably, one R group is an alkyl or alkenyl group. The remaining R groups are suitably hydrogen. Each alkyl or alkenyl group may contain from 6 to 30, such as from 8 to 24, carbon atoms. The polycarboxylic acid may be an alkyl or alkenyl substituted succinic acid, preferably an alkenyl substituted succinic acid. Examples of such polycarboxylic acids include C20-24 alkenyl succinic acid, dodecenyl succinic acid (such as (2-dodecen-1-yl)succinic acid), nonenyl succinic acid, octadecenyl succinic acid and octenyl succinic acid. One R group may be a polyisobutenyl group and the remaining R groups may be hydrogen. The polyisobutenyl group suitably has a number average molecular weight of from 100 to 2000, preferably from 100 to 1000, for example 260 or 550. The polycarboxylic acid may be a polyisobutenyl succinic acid, for example wherein the polyisobutenyl group has a number average molecular weight of 260 or 550. Two R groups on the same carbon atom may be taken together to form a methylene (=CH2) group. The polycarboxylic acid may comprise one or more such methylene groups. Two R groups on the same carbon atom may be taken together to form a methylene (=CH2) group and the remaining R groups may be hydrogen. The polycarboxylic acid may be itaconic acid. When n is 2 or more, two R groups on adjacent carbon atoms may be taken together to form a double bond. The polycarboxylic acid may comprise one or more such double bonds. The double bond may be in a cis or trans configuration. Two R groups on adjacent carbon atoms may be taken together to form a double bond and the remaining R groups may be hydrogen. The polycarboxylic acid may be maleic acid or fumaric acid. The polycarboxylic acid may be of the formula HOOC(CH2)nCOOH, wherein n is from 0 to 30. n is suitably from 1 to 20, preferably from 2 to 16, more preferably from 4 to 12, for example from 5 to 10. The polycarboxylic acid may be selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, or dodecanedioic acid. Preferably, the polycarboxylic acid may be selected from pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, or dodecanedioic acid. The polycarboxylic acid may be of the formula HOOC(CH2)mX1(CH2)m2COOH, wherein m+m2 is from 0 to 30 and X1 is O, S, or NR17 wherein R17 is hydrogen or a hydrocarbyl group. m+m2 is suitably from 1 to 20, preferably from 2 to 16, more preferably from 2 to 12, for example from 2 to 6. m and m2 may each independently be from 0 to 30, suitably from 1 to 19, preferably from 1 to 15, more preferably from 1 to 11, for example from 1 to 5. R17 may be a hydrocarbyl group, such as an alkyl or alkenyl group. The hydrocarbyl group may contain from 1 to 12 carbon atoms, preferably from 1 to 6 carbon atoms. Preferably, R17 is hydrogen. X1 is preferably O or S. The polycarboxylic acid may be selected from diglycolic acid, thiodiglycolic acid, 3,3’-thiodipropanoic acid, or iminodiacetic acid, preferably from diglycolic acid or thiodiglycolic acid. The polycarboxylic acid may be of the formula HOOCCH2(OCH2CHR18)XOCH2COOH, wherein x is from 1 to 30 and each R18 is independently hydrogen or a hydrocarbyl group. x is suitably from 1 to 20, preferably from 2 to 16, more preferably from 4 to 14, for example from 6 to 12, such as 10. Each R18 may independently be a hydrocarbyl group, such as an alkyl group. The alkyl group may contain from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms. The alkyl group is preferably methyl. In some embodiments, a portion of R18 groups are hydrocarbyl groups (such as methyl groups) and the remaining R18 groups are hydrogen. Preferably, each R18 is hydrogen. The polycarboxylic acid may be a poly(ethylene glycol)bis(carboxymethyl) ether. The poly(ethylene glycol)bis(carboxymethyl) ether may contain from 1 to 20 ethylene oxide units (i.e. -CH2CH2O-), preferably from 2 to 16 ethylene oxide units, more preferably from 4 to 14 ethylene oxide units, for example from 6 to 12 ethylene oxide units, such as 10 ethylene oxide units. The polycarboxylic acid may be a poly(ethylene glycol)bis(carboxymethyl) ether containing 10 ethylene oxide units. The polycarboxylic acid may comprise a cyclic group. The cyclic group may be substituted, for example with alkyl or alkenyl groups. The carboxyl groups of the polycarboxylic acid may be attached directly to the cyclic group, or via an alkyl or alkenyl group. The cyclic group may be a cycloaliphatic group. Examples of cycloaliphatic groups include cyclohexane and cyclohexene. The polycarboxylic acid may be 1,2-cyclohexanedicarboxylic acid or 1,4-cyclohexanedicarboxylic acid. The cyclic group may be an aromatic group. Examples of aromatic groups include benzene and naphthalene. The polycarboxylic acid may be selected from phthalic acid, isophthalic acid, terephthalic acid, homophthalic acid, 1,2,4-benzenetricarboxylic acid, pyromellitic acid, 1,2-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid. 1,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, or 2,7-naphthalenedicarboxylic acid. The polycarboxylic acid may be a dimer acid. Such compounds are formed from the dimerisation of unsaturated acids, for example unsaturated fatty acids having from 6 to 50, suitably from 8 to 40, preferably from 10 to 36, for example from 10 to 20 carbon atoms, or from 16 to 20 carbon atoms. The dimer acid may be hydrogenated or unhydrogenated. Preferably, the dimer acid is hydrogenated. The dimer acid may have from 12 to 100 carbon atoms, preferably from 16 to 72 carbon atoms such as from 20 to 40 carbon atoms, for example from 32 to 40 carbon atoms. Preferred dimer acids comprise C36 dimer acids such as those prepared by dimerising oleic acid, linoleic acid and mixtures comprising oleic and linoleic acid, for example, tall oil fatty acids. Preferably, the dimer acid comprises a dimer acid prepared by dimerising oleic acid. The dimer acid may be a hydrogenated C36 dimer acid. A reactive equivalent of the polycarboxylic acid may be used. The reactive equivalent may be an acid chloride of the polycarboxylic acid. The acid chloride of the polycarboxylic acid suitably does not comprise any free carboxylic acid groups. The reactive equivalent may be an ester of the polycarboxylic acid. The ester of the polycarboxylic acid suitably does not comprise any free carboxylic acid groups. The ester of the polycarboxylic acid is suitably a hydrocarbyl ester, such as an alkyl ester, an alkenyl ester, an aryl ester, an aralkyl ester, or an alkaryl ester. Preferably the ester is an alkyl ester. The alkyl ester is suitably formed by reacting the polycarboxylic acid with an alkanol. The alkanol suitably contains from 1 to 10 carbon atoms, such as from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms. The alkanol is preferably methanol. The alkyl ester is preferably a methyl ester. Suitably, the or each polycarboxylic acid or the acid chloride or ester thereof may be selected from oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, maleic acid, fumaric acid, malic acid, tartaric acid, citric acid, C20-24 alkenyl succinic acid, dodecenyl succinic acid (such as (2-dodecen-1-yl)succinic acid), nonenyl succinic acid, octadecenyl succinic acid, octenyl succinic acid, polyisobutenylsuccinic acid, itaconic acid, 1,2-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, homophthalic acid, 1,2,4-benzenetricarboxylic acid, pyromellitic acid, 1,2-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diglycolic acid, thiodiglycolic acid, 3,3’-thiodipropanoic acid, iminodiacetic acid, poly(ethylene glycol)bis(carboxymethyl) ether, a dimer acid, or an acid chloride or ester thereof. Suitably, the or each polycarboxylic acid or the acid chloride or ester thereof may be selected from oxalic acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, malic acid, tartaric acid, citric acid, 1,4-cyclohexanedicarboxylic acid, isophthalic acid, terephthalic acid, diglycolic acid, thiodiglycolic acid, poly(ethylene glycol)bis(carboxymethyl) ether, a hydrogenated dimer acid or an acid chloride or ester thereof. Suitably, the or each polycarboxylic acid or the acid chloride or ester thereof may be selected from oxalic acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, malic acid, tartaric acid, citric acid, 1,4-cyclohexanedicarboxylic acid, isophthalic acid, diglycolic acid, thiodiglycolic acid, poly(ethylene glycol)bis(carboxymethyl) ether, a hydrogenated dimer acid, or an acid chloride or ester thereof. Preferably, the or each polycarboxylic acid or the acid chloride thereof may be selected from succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, malic acid, tartaric acid, citric acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, diglycolic acid, thiodiglycolic acid, poly(ethylene glycol)bis(carboxymethyl) ether, a hydrogenated dimer acid, oxalyl chloride, isophthaloyl chloride, or terephthaloyl chloride. In some embodiments, mixtures of two or more different polycarboxylic acids may be used to make the polymer. For example, a mixture of dodecanedioic acid and tartaric acid may be used. Preferably, the or each first monomer may be a cyclic anhydride selected from one or more of formula (I), of formula (II) and of formula (III): wherein in formula (I) R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group, or R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; in formula (II) R3 and R4 are each independently selected from hydrogen, an alkyl group and an alkenyl group, or R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; and in formula (III) X is CR9R10, O, S, or NR11; R5, R6, R7, R8, R9, R10, and R11 are each independently selected from hydrogen, an alkyl group and an alkenyl group, and / or any of R5, R6, R7, R8, R9, R10, and R11 together with the atoms to which they are attached represent an optionally substituted cyclic group; or a polycarboxylic acid or an acid chloride or ester thereof, wherein the polycarboxylic acid is selected from: a polycarboxylic acid of the formula HOOC(CR2)nCOOH, wherein n is from 0 to 30; and each R is independently hydrogen or a substituent; and / or two R groups on the same carbon atom are taken together to form a methylene (=CH2) group; and / or when n is two or more, two R groups on adjacent carbon atoms are taken together to form a double bond; and n is suitably from 1 to 20, preferably from 2 to 16, more preferably from 2 to 12, for example from 2 to 10; a polycarboxylic acid of the formula HOOC(CH2)mX1(CH2)m2COOH, wherein m+m2 is from 0 to 30 and X1 is O, S, or NR17 wherein R17 is hydrogen or a hydrocarbyl group; a polycarboxylic acid of the formula HOOCCH2(OCH2CHR18)XOCH2COOH, wherein x is from 1 to 30 and each R18 is independently hydrogen or a hydrocarbyl group; a polycarboxylic acid comprising a cyclic group; or a dimer acid. Preferably, the or each first monomer may be a cyclic anhydride selected from one or more of succinic anhydride, maleic anhydride, glutaric anhydride, a C6-30 alkenyl succinic anhydride such as C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, octadecyl succinic anhydride, or octyl succinic anhydride, a branched alkenyl succinic anhydride such as tetrapropenyl succinic anhydride or polyisobutenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride and homophthalic anhydride; or a polycarboxylic acid or an acid chloride or ester thereof selected from oxalic acid, succinic acid, adipic acid, pimelicacid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, malic acid, tartaric acid, citric acid, 1,4-cyclohexanedicarboxylic acid, isophthalic acid, terephthalic acid, diglycolic acid, thiodiglycolic acid, poly(ethylene glycol)bis(carboxymethyl) ether, a hydrogenated dimer acid or an acid chloride or ester thereof. Preferably, the or each first monomer may be a cyclic anhydride selected from one or more of succinic anhydride, maleic anhydride, glutaric anhydride, a C6-30 alkenyl succinic anhydride such as C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, octadecyl succinic anhydride, or octyl succinic anhydride, phthalic anhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride and homophthalic anhydride; or a polycarboxylic acid or an acid chloride or ester thereof selected from oxalic acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, malic acid, tartaric acid, citric acid, 1,4-cyclohexanedicarboxylic acid, isophthalic acid, terephthalic acid, diglycolic acid, thiodiglycolic acid, poly(ethylene glycol)bis(carboxymethyl) ether, a hydrogenated dimer acid or an acid chloride or ester thereof. Preferably, the or each first monomer may be selected from one or more of sebacic acid, dodecanedioic acid, pimelic acid, hydrogenated dimer acid, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride. The polycarboxylic acid or reactive equivalent thereof discussed herein may be commercially available or may be prepared using procedures well known in the art. The or each of the one or more second monomers used to make the polymer is a polyfunctional monomer having at least one reactive amino group. Mixtures of two or more different second monomers (i.e. different polyfunctional monomers each having at least one reactive amino group) may be used to make the polymer. Any suitable polyfunctional monomer having at least one reactive amino group may be used to make the polymer, as would be understood by the person skilled in the art. By the term “polyfunctional monomer” we mean a monomer with at least two reactive groups. By the term “reactive group” we mean a group that reacts or may react with the first monomer. At least one of the reactive groups is a reactive amino group. The other reactive groups in the polyfunctional monomer may be reactive amino groups, or may be reactive groups other than amino groups, such as hydroxyl groups. Reactive amino groups are suitably primary amino groups or secondary amino groups. The polyfunctional monomer may comprise at least one reactive amino group and at least one hydroxyl group. The polyfunctional monomer may be an alkanolamine or an alkoxylated alkanolamine. Examples of suitable alkanolamines and alkoxylated alkanolamines include ethanolamine, isopropanolamine, mixed isopropanolamines, aminomethyl propanol, 2-aminobutanol, tromethamine, N-methylmethanolamine, N-methylethanolamine, diethanolamine, N-methylpropanolamine, dipropanolamine, diisopropylamine, N-methylbutanolamine, dibutanolamine, N-ethylmethanolamine, N-ethylethanolamine, N-ethylpropanolamine, N-ethylbutanolamine, N-propylmethanolamine, N-propylethanolamine, N-propylpropanolamine, N-propylbutanolamine, N-butylmethanolamine, N-butylethanolamine, N-butylpropanolamine, N-butylbutanolamine, 2-(2-aminoethoxy)ethanol, aminoethyl propanol, aminomethyl propanediol, and hydroxyethylbenzylamine. The polyfunctional monomer may be a monoalkanolamine or a dialkanolamine. The polyfunctional monomer is preferably a monoalkanolamine, such as ethanolamine. In some embodiments, the polyfunctional monomer does not comprise hydroxyl groups. The polyfunctional monomer may comprise at least two reactive amino groups. The polyfunctional monomer may be a polyamine. By “polyamine” we mean a compound having two or more amino groups. The polyamine may comprise further functional groups, such as ether groups and / or hydroxyl groups. The polyamine may be a diamine. The diamine may be an aliphatic diamine or an aromatic diamine. The aliphatic diamine may be a cycloaliphatic diamine such as isophorone diamine. The diamine may be alkylene diamine, an N-hydrocarbyl alkylene diamine, or an N,N’-dihydrocarbyl alkylene diamine. Examples of suitable diamines include ethylene diamine, trimethyl-1,6-hexanediamine and coco propylene diamine (commercially available as Duomeen CD). The polyamine may be a polyalkylene polyamine, such as a polyethylene polyamine. Suitable polyethylene polyamines include diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA) and mixtures and isomers thereof. The polyamine may comprise one or more hydroxyl groups and / or one or more ether groups. The polyamine may comprise one or more hydroxyalkyl groups, or one or more alkoxylated hydroxyalkyl groups. The polyamine may be a hydroxyalkylaminoalkylamine, an alkoxylated hydroxyalkylaminoalkylamine, a di(hydroxyalkyl)aminoalkylamine, or an alkoxylated di(hydroxyalkyl)amino alkylamine. Suitable polyamines of this type include (2-aminoethyl)aminoethanol, ethoxylated (2-aminoethyl)aminoethanol, di(hydroxyethyl)aminopropylamine, and ethoxylated di(hydroxyethyl)aminopropylamine. The polyamine may comprise one or more ether groups. The polyamine may be a polyether diamine. The polyether diamine suitably has a molecular weight of from 150 to 6000, preferably from 200 to 4000 or from 400 to 3000, for example from 600 to 2000. The polyether diamine may have a molecular weight of 600, 900, or 2000. The polyether diamine may have a weight average molecular weight of from 150 to 6000, preferably from 400 to 3000, for example from 600 to 2000. The polyether diamine may have a weight average molecular weight of from 150 to 1800, such as from 400 to 1500, for example from 600 to 1000. The polyether diamine may have a weight average molecular weight of from 1000 to 6000, such as from 1500 to 3000, for example from 1800 to 2000. The polyether diamine may have a weight average molecular weight of 600, 900, or 2000. The polyether diamine comprises a polyether backbone. The polyether backbone may be selected from polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer of polyethylene glycol (PEG) and polypropylene glycol (PPG). The copolymer of PEG and PPG may be a block copolymer or a random copolymer. Polyamines of this type are commercially available as Jeffamine D and Jeffamine ED compounds. Examples of suitable polyether diamines include poly(propylene glycol) bis(aminopropyl)ether (preferably having a molecular weight of around 230), Jeffamine ED-600, Jeffamine ED-900, and Jeffamine ED-2003. In some embodiments, the polyether diamine is selected from poly(propylene glycol) bis(aminopropyl)ether (preferably having a molecular weight of around 230), Jeffamine ED-600, and Jeffamine ED-900. In some embodiments, the polyether diamine is selected from poly(propylene glycol) bis(aminopropyl)ether (preferably having a molecular weight of around 230), Jeffamine ED-600, and Jeffamine ED-2003. In some embodiments, the polyether diamine is selected from poly(propylene glycol) bis(aminopropyl)ether (preferably having a molecular weight of around 230), Jeffamine ED-900, and Jeffamine ED-2003. The polyfunctional monomer may be a monomer of formula (IV): R19—N-(- R20--X2-)—H ' Zn6 (IV) wherein R19 is H or an optionally substituted hydrocarbyl group; each R20 is independently a hydrocarbylene group; each X2 is independently NR21 or O; each R21 is independently H or an optionally substituted hydrocarbyl group; and n6 is 1 or more. R19 is H or an optionally substituted hydrocarbyl group. R19 may be H, an unsubstituted hydrocarbyl group, or a substituted hydrocarbyl group of formula (A): —(-R20a—X2a^—H ' 'n7 (A) wherein each R20a is independently a hydrocarbylene group; each X2a is independently NR21a or O; each R21a is independently H or an optionally substituted hydrocarbyl group; and n7 is 1 or more. Each R20a is suitably an alkylene group. The alkylene group suitably contains from 1 to 6 carbon atoms. The alkylene group may independently be selected from ethylene (such as 1,2-ethylene), propylene (such as 1,2-propylene or 1,3-propylene) or butylene (such as 1,2-butylene, 1,3-butylene, or 1,4-butylene). Each R20a may independently be -CH2CH2-, -CH2CH(CH3)-, or CH(CH3)CH2-. Each R20a is preferably -CH2CH2-. Suitably, each R21a is independently H or an unsubstituted hydrocarbyl group. The hydrocarbyl group is suitably an alkyl or alkenyl group. The hydrocarbyl group may be a Ci to C12 alkyl or alkenyl group, preferably a Ci to Ce alkyl or alkenyl group, for example a Ci to C4 alkyl or alkenyl group. Suitably, each R21a is independently H or a Ci to C4 alkyl group. Preferably, each R21a is H. Each X2a is preferably O. Suitably, n7 is from 1 to 30, such as from 1 to 20, for example from 1 to 10. n7 may be 1 or 2. Preferably, n7 is 1. Suitably, R19 is H or an unsubstituted hydrocarbyl group. The hydrocarbyl group is suitably an alkyl or alkenyl group. The hydrocarbyl group may be a Ci to C12 alkyl or alkenyl group, preferably a Ci to Ce alkyl or alkenyl group, for example a Ci to C4 alkyl or alkenyl group. Suitably, R19 is H or a Ci to C4 alkyl group. Preferably, R19 is H. Each R20 is suitably an alkylene group. The alkylene group suitably contains from 1 to 6 carbon atoms. The alkylene group may independently be selected from ethylene (such as 1,2-ethylene), propylene (such as 1,2-propylene or 1,3-propylene) or butylene (such as 1,2-butylene, 1,3-butylene, or 1,4-butylene). Each R20 may independently be -CH2CH2-, -CH2CH(CH3)-, or CH(CH3)CH2-. Each R20 is preferably -CH2CH2-. Each X2 is suitably independently NR20 or O wherein each R20 is independently Horan optionally substituted hydrocarbyl group. Suitably, at least one X2 is NR20. Suitably, each R20 is independently H or an unsubstituted hydrocarbyl group. The hydrocarbyl group is suitably an alkyl or alkenyl group. The hydrocarbyl group may be a Ci to C12 alkyl or alkenyl group, preferably a Ci to Ce alkyl or alkenyl group, for example a Ci to C4 alkyl or alkenyl group. Suitably, each R20 is independently H ora Ci to C4 alkyl group. Preferably, each R20 is H. Suitably, n6 is from 1 to 150, preferably from 1 to 50, for example from 1 to 10. n6 may be 1 or 2. For example, n6 may be 1. For example, the polyfunctional monomer may be a monomer of formula (IV): R19—N—F—R20—X2-4— H / n6 (IV) wherein R19 is H, a Ci to C4 alkyl group, or a substituted hydrocarbyl group of formula (A): —F—R2Oa-X2a4-H (A) R20a is an alkylene group containing from 1 to 6 carbon atoms; X2a is O; n7 is 1; R20 is an alkylene group containing from 1 to 6 carbon atoms; X2 is O; and n6 is 1. For example, the polyfunctional monomer may be a monomer of formula (IV): (IV) wherein R19 is H; each R20 is -CH2CH2-; each X2 is NH; and n6 is from 1 to 10. For example, the polyfunctional monomer may be a monomer of formula (IVA): (IVA) wherein each R20 is independently -CH2CH2-, -CH2CH(CH3)-, or CH(CH3)CH2-; and n6 is from 1 to 150. The polyfunctional monomer may be a monomer of formula (IVB): wherein each R20and R21 is independently-CH2CH2-, -CH2CH(CH3)-, orCH(CH3)CH2-; and each of n8, n9 and n10 is from 1 to 150. In some preferred embodiments, R20 is -CH2CH(CH3)-, R21 is independently -CH2CH2-, the sum of n8 and n10 is from 2 to 10, preferably from 5 to 7, and n9 is from 5 to 100, preferably from 10 to 50. In some preferred embodiments, R20 is -CH2CH(CH3)-, R21 is -CH2CH2-, the sum of n8 and n10 is from 3 to 7, and n9 is from 5 to 15. Preferably in the formula (IVB), R20 is -CH2CH(CH3)-, R21 is independently -CH2CH2-, the sum of n8 and n10 is from 2 to 10, preferably from 5 to 7, and n9 is from 5 to 100, preferably from 30 to 50. In some embodiments, R20 is -CH2CH(CH3)-, R21 is -CH2CH2-, the sum of n8 and n10 is from 5 to 7, and n9 is from 10 to 15. In some embodiments, R20 is -CH2CH(CH3)-, R21 is -CH2CH2-, the sum of n8 and n 10 is from 3 to 4, and n9 is from 5 to 10. Suitably, the polyfunctional monomer may be selected from ethanolamine, diethanolamine, ethylene diamine, coco propylene diamine, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), trimethyl-1,6-hexane diamine, isophorone diamine or a polyether diamine (preferably polypropylene glycol bis(aminopropyl) ether with MW around 230Da, Jeffamine ED-600, Jeffamine ED-900, or Jeffamine ED-2003). Suitably, the polyfunctional monomer may be selected from ethylene diamine, coco propylene diamine, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), trimethyl-1,6-hexane diamine, isophorone diamine or a polyether diamine (preferably polypropylene glycol bis(aminopropyl) ether with MW around 230Da, Jeffamine ED-600, Jeffamine ED-900, or Jeffamine ED-2003). Suitably, the polyfunctional monomer may be selected from coco propylene diamine, triethylenetetramine (TETA), tetraethylenepentamine (TEPA), ora polyether diamine (preferably polypropylene glycol bis(aminopropyl) ether with MW around 230Da, Jeffamine ED-600, Jeffamine ED-900, or Jeffamine ED-2003). In one embodiment, the polymer may be the reaction product of monomers comprising one (i.e. a single) polycarboxylic acid or reactive equivalent thereof and one (i.e. a single) polyfunctional monomer having at least one reactive amino group. In other embodiments, the polymer may be the reaction product of monomers comprising two different polycarboxylic acids or reactive equivalents thereof, for example a cyclic anhydride and a polycarboxylic acid or an acid chloride or ester thereof, and one (i.e. a single) polyfunctional monomer having at least one reactive amino group, or the polymer may be the reaction product of monomers comprising one (i.e. a single) polycarboxylic acid or reactive equivalent thereof and two different polyfunctional monomers each having at least one reactive amino group. The combined amount of the one or more first monomers and the one or more second monomers may be at least 50 mol%, suitably at least 75 mol%, preferably at least 90 mol%, for example at least 95 wt% of the monomers that are reacted to obtain the polymer. The combined amount of the one or more first reactants and the one or more second reactants may be at least 50 mol%, suitably at least 75 mol%, preferably at least 90 mol%, for example at least 95 wt% of the reactants that are reacted to obtain the nitrogen containing compound. In one embodiment, the polymer may be the reaction product of monomers consisting essentially of or consisting of one (i.e. a single) polycarboxylic acid or reactive equivalent thereof and one (i.e. a single) polyfunctional monomer having at least one reactive amino group. In other embodiments, the polymer may be the reaction product of monomers consisting essentially of or consisting of two different polycarboxylic acids or reactive equivalents thereof, for example a cyclic anhydride and a polycarboxylic acid or an acid chloride or ester thereof, and one (i.e. a single) polyfunctional monomer having at least one reactive amino group, or the polymer may be the reaction product of monomers consisting essentially of or consisting of one (i.e. a single) polycarboxylic acid or a reactive equivalent thereof and two different polyfunctional monomers each having at least one reactive amino group. The polymer for use herein may be the reaction product of monomers comprising the one or more first monomers and one or more second monomers as disclosed herein and additionally one or more third monomers. In other words, the polymer may be the reaction product of monomers comprising one or more first monomers as disclosed herein, one or more second monomers as disclosed herein and one or more third monomers. The one or more third monomers may for example act as end capping groups and / or may introduce additional functional groups to the polymers. The one or more third monomers may be selected to impart the desired groups and / or properties to the polymer by the person skilled in the art. In embodiments relating to nitrogen containing compounds as defined herein, the third monomer may be referred to as a third reactant. The combined amount of the one or more first monomers, the one or more second monomers, and the one or more third monomers may be at least 50 mol%, suitably at least 75 mol%, preferably at least 90 mol%, for example at least 95 wt% of the monomers that are reacted to obtain the polymer. The combined amount of the one or more first reactants, the one or more second reactants, and the one or more third reactants may be at least 50 mol%, suitably at least 75 mol%, preferably at least 90 mol%, for example at least 95 wt% of the reactants that are reacted to obtain the nitrogen containing compound. The polymer for use herein may be the reaction product of monomers consisting essentially of or consisting of the one or more first monomers and one or more second monomers as disclosed herein and additionally one or more third monomers. In other words, the polymer may be the reaction product of monomers consisting essentially of or consisting one or more first monomers as disclosed herein, one or more second monomers as disclosed herein and one or more third monomers. The polymer for use herein is suitably the reaction product of no more than four different monomers. Preferably, the polymer is the reaction product of no more than three different monomers. For example, the polymer may be the reaction product of one first monomer, one second monomer, and one third monomer, orthe reaction product of two different first monomers and one second monomer as disclosed herein. In some preferred embodiments, the polymer is the reaction product of only two different monomers, i.e. one first monomer and one second monomer as disclosed herein (and no further monomers). Examples of suitable third monomers include one or more of the following: (i) monocarboxylic acids or esters thereof; (ii) hydroxycarboxylic acids or cyclic esters thereof; (iii) polyols; (iv) epoxide compounds; (v) monoalcohols; and (vi) monofunctional monomers having a reactive amino group. The third monomer may be (i) a monocarboxylic acid or an ester thereof. Suitable monocarboxylic acids may be aliphatic or aromatic. The aliphatic monocarboxylic acid may be cycloaliphatic. The aliphatic monocarboxylic acid may be saturated or unsaturated. The monocarboxylic acid may contain from 2 to 40 carbon atoms, suitably from 4 to 30 carbon atoms, preferably from 6 to 20 carbon atoms, for example from 8 to 18 carbon atoms. The monocarboxylic acid may be a fatty acid. Examples of suitable monocarboxylic acids or esters thereof include hexanoic acid, octanoic acid, decanoic acid, lauric acid, myristic acid, myristoleic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linolelaidic acid, arachidic acid, arachidonic acid, behenic acid, erucic acid, and esters (preferably methyl esters) thereof. Preferably, the monocarboxylic acid is selected from propionic acid, hexanoic acid, lauric acid, stearic acid, oleic acid, or erucic acid. The third monomer may be (ii) a hydroxycarboxylic acid or a cyclic ester thereof. Suitable hydroxycarboxylic acids comprise one or more hydroxy groups and one or more carboxylic acid groups. The hydroxycarboxylic acid may be a monocarboxylic acid comprising one or more hydroxy groups. By the term “cyclic ester” of a hydroxycarboxylic acid we mean a compound comprising a cyclic group, wherein the cyclic group comprises one or more ester groups. The ester may be a cyclic monoester or a cyclic diester. The cyclic ester may correspond to a single cyclised molecule of the hydroxycarboxylic acid. This may, for example, be formed by an intramolecular reaction between the hydroxy group and the carboxylic acid group on one molecule of the hydroxycarboxylic acid. Alternatively, the cyclic ester may correspond to a cyclic dimer of a hydroxycarboxylic acid. This may, for example, be formed by an intermolecular reaction between the hydroxy groups and the carboxylic acid groups on two molecules of the hydroxycarboxylic acid. Examples of suitable hydroxycarboxylic acids or cyclic esters thereof include glycolic acid, lactic acid, hydroxy butyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxystearic acid (preferably 12-hydroxystearic acid), dihydroxystearic acid, 2,2-bis(hydroxymethyl)propionic acid, mandelic acid, ricinoleic acid, malic acid, tartaric acid, citric acid, y-butyrolactone, 6-valerolactone, s-caprolactone, menthide, D-lactide, L-lactide, or DL-lactide. Preferably, the hydroxycarboxylic acid is selected from ricinoleic acid or citric acid. The third monomer may be (iii) a polyol. The term polyol is used to refer to any compound including two or more hydroxy (OH) functional groups. In some embodiments the or each polyol may comprise carbon, hydrogen and oxygen atoms, and optionally additionally nitrogen atoms. In other embodiments, the or each polyol may consist essentially of or consist of carbon, hydrogen and oxygen atoms. Suitable polyols for preparing the polymer may be compounds having from 2 to 10, preferably from 2 to 6, more preferably 2 or 3, hydroxy groups. Examples of suitable polyols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, 1,12-dodecanediol, trimethylolpropane, 2-ethyl-1,3,-hexanediol, 2,2-diethyl-1,3-propanediol, 2,2- bis(hydroxymethyl)propionic acid, pentaerythritol, sorbitol, xylitol, glycerol, neopentyl glycol, diethylene glycol, triethylene glycol, di propylene glycol, tripropylene glycol, polyethylene glycol (PEG), for example having a molecular weight of from 150 to 6000, polypropylene glycol (PPG), for example having a molecular weight of from 400 to 2000, castor oil, polyoxyethylene (80) sorbitan monooleate (also known as Tween® 80), 2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylate, N-methyl diethanolamine, N-butyl diethanolamine, triethanolamine and diethanolamine, tris(2-hydroxyethyl)methylammonium methylsulfate, and polyols formed by reaction of a hydroxy substituted cyclic ester or cyclic carbonate, such as glycerol carbonate or gluconolactone, with a suitable primary or secondary amine compound, such as ethanolamine, dipropylamine, hexylamine, dodecylamine, phenethylamine, dipropylamine, ethylenediamine, or a polyether polyamine. The third monomer may be (iv) an epoxide compound. Suitable epoxide compounds may comprise one or more than one epoxide group. For example, suitable epoxide compounds may comprise two epoxide groups. Examples of suitable epoxide compounds include 1,2-epoxydodecane, ethyl glycidyl ether, isopropylglycidyl ether, 2-ethylhexyl glycidyl ether, octyl glycidyl ether, nonyl glycidyl ether, decyl glycidyl ether, butyl glycidyl ether (such as n-butyl glycidyl ether), 1,2-epoxyhexane, epichlorohydrin, glycidyltrimethylammonium chloride, cyclopentene oxide, cyclohexene oxide, poly(ethylene glycol) diglycidyl ether, poly(propylene glycol) diglycidyl ether and poly(butylene glycol) diglycidyl ether. The third monomer may be (v) a monoalcohol. Suitable monoalcohols may be aliphatic or aromatic. The aliphatic monoalcohol may be cycloaliphatic. The aliphatic monoalcohol may be saturated or unsaturated. The monoalcohol may contain from 2 to 40 carbon atoms, suitably from 4 to 30 carbon atoms, preferably from 6 to 20 carbon atoms, for example from 8 to 18 carbon atoms. The monoalcohol may be a fatty alcohol. Examples of suitable monoalcohols include hexanol, octanol, 2-ethylhexanol, decanol, dodecanol alcohol, myristyl alcohol, myristoleyl alcohol, palmityl alcohol, palmitoleyl alcohol, stearyl alcohol, oleyl alcohol, elaidyl alcohol, linoleyl alcohol, linolelaidyl alcohol, arachidyl alcohol, arachidonyl alcohol, behenyl alcohol, erucyl alcohol, benzyl alcohol, and choline chloride. Preferably, the monoalcohol is hexanol or oleyl alcohol. The third monomer may be (vi) a monofunctional monomer having a reactive amino group. Suitable monofunctional monomers having a reactive amino group have one reactive amino group and no other reactive groups. The monofunctional monomer may contain other functional groups that are not reactive groups, such as tertiary amino groups or ether groups. The monofunctional monomer may be an aliphatic monoamine (such as a fatty alkyl amine), an N,N-dialkylaminoalkylamine, ora polyether monoamine. The polyether monoamine suitably comprises a polyether backbone selected from polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer of polyethylene glycol (PEG) and polypropylene glycol (PPG). The copolymer of PEG and PPG may be a block copolymer or a random copolymer. The polyether backbone is suitably capped at one end with the reactive amino group, and capped at the other end with an alkyl group (preferably a methyl group). The polyether monoamine suitably has a molecular weight of from 150 to 6000, preferably from 400 to 3000, for example from 600 to 2000. The polyether monoamine may have a weight average molecular weight of from 150 to 6000, preferably from 400 to 3000, for example from 600 to 2000. Examples of suitable monofunctional monomers having a reactive amino group include propylamine, dipropylamine, butylamine, hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, tallow alkyl amine, benzylamine, phenethylamine, 3-dimethylaminopropylamine (DMAPA), or Jeffamine M-1000 (which is commercially available). Preferably, the monofunctional monomer having a reactive amino group is selected from dodecylamine, N,N-dimethylaminopropylamine (DMAPA), or Jeffamine M-1000. The polymers may be prepared from the first, second and optionally third monomers by any suitable method, as would be known to the person skilled in the art. The polymerisation reaction will typically be conducted in the presence of a suitable polymerisation catalyst, such as tin(ll) ethylhexanoate, tin(ll) oxalate, p-toluenesulfonic acid, methanesulfonic acid, or sulfuric acid. These catalysts may also be used in reactions that form nitrogen containing compounds that are not polymers. Another suitable catalyst system comprises 1,8-diazabicyclo(5.4.0)undec-7-ene and dicyclohexylurea. The polymerisation reaction may be carried out for any suitable length of time, such as at least 1 hour, preferably at least 3 hours, for example at least 5 hours. The polymerisation reaction may be carried out at any suitable temperature, such as from 50 to 300°C, preferably from 150 to 250°C. Suitable molar ratios of the first, second and optional third monomers may be used to prepare the polymers. Thus repeat units in the polymer derived from the first, second and third monomers when present may be present in the polymer in any suitable molar ratio and in any suitable arrangement. Suitably, the polymer is not further reacted after the reaction of the monomers. For example, the polymer is suitably not quaternised, e.g. by reacting the polymer with a quaternising agent. Suitably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of: (i) a cyclic anhydride of formula (I) wherein R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group; and (ii) a dicarboxylic acid or an acid chloride or ester thereof, and wherein the or each second monomer is one or more of: (iii) a polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group; (iv) a polyether diamine; and (v) a diamine. Suitably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of: (i) a cyclic anhydride of formula (I) wherein R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group; and (ii) a dicarboxylic acid or an acid chloride or ester thereof, and wherein the or each second monomer is one or more of: (iii) a polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group; (iv) a polyether diamine; and (v) a diamine. Suitably, the polymer may be the reaction product of monomers comprising, consisting essentially of, or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is a dicarboxylic acid or an acid chloride or ester thereof; and wherein the or each second monomer is one or more polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group. Suitably, the polymer may be the reaction product of monomers comprising, consisting essentially of, or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is a polycarboxylic acid of the formula HOOC(CH2)nCOOH, wherein n is from 0 to 30. or an acid chloride or ester thereof; and wherein the or each second monomer is one or more of a monoalkanolamine or a dialkanolamine. Suitably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of a cyclic anhydride of formula (I) wherein R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group; and wherein the or each second monomer is one or more polyether diamine (for example wherein the polyether backbone is selected from polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer of polyethylene glycol (PEG) and polypropylene glycol (PPG)). Suitably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of a cyclic anhydride of formula (I) wherein R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group; and wherein the or each second monomer is one or more monomer of the formula (IVA) as defined herein. Suitably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of a cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group); and wherein the or each second monomer is one or more monomer of the formula (IVA) as defined herein. Suitably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of a cyclic anhydride of formula (I) wherein R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group; and wherein the or each second monomer is one or more polyether diamine (for example wherein the polyether backbone is selected from polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer of polyethylene glycol (PEG) and polypropylene glycol (PPG)). Suitably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of a cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group); and wherein the or each second monomer is one or more polyether diamine (for example wherein the polyether backbone is selected from polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer of polyethylene glycol (PEG) and polypropylene glycol (PPG)). Suitably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is one or more of a cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group); and wherein the or each second monomer is one or more polyether diamine (for example wherein the polyether backbone is selected from polyethylene glycol (PEG), polypropylene glycol (PPG), or a copolymer of polyethylene glycol (PEG) and polypropylene glycol (PPG)). Suitably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is a dicarboxylic acid or an acid chloride or ester thereof, and wherein the or each second monomer is one or more of a polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group (such as an alkanol amine). Suitably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is a dicarboxylic acid or an acid chloride or ester thereof, and wherein the or each second monomer is one or more polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group (such as an alkanol amine). Suitably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the first monomer is pimelic acid or an acid chloride or ester thereof, and wherein the or each second monomer is one or more of a polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group (such as an alkanol amine). Suitably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the first monomer is pimelic acid or an acid chloride or ester thereof, and wherein the or each second monomer is one or more polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group (such as an alkanol amine). Preferably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of pimelic acid or an acid chloride or ester thereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride, and wherein the or each second monomer is one or more monomer of the formula (IVA) as defined herein. Preferably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of pimelic acid or an acid chloride or ester thereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride, and wherein the or each second monomer is one or more monomer of the formula (IVA) as defined herein. Preferably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of sebacic acid or an acid chloride or ester thereof, pimelic acid or an acid chloride or ester thereof, dodecanedioic acid or an acid chloride or ester thereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride, C20-C24 alkenyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, C16 terminal olefin-derived alkenyl succinic anhydride, and tetrapropenyl succinic anhydride, and wherein the one or more second monomers are selected from one or more of diethanolamine, trimethyl-1,6-hexanediamine, isophorone diamine, poly(propylene glycol) bis(aminopropyl ether), Jeffamine ED-600, Jeffamine ED-900, and Jeffamine ED-2003. Preferably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of sebacic acid or an acid chloride or ester thereof, pimelic acid or an acid chloride or ester thereof, dodecanedioic acid or an acid chloride or ester thereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride, C20-C24 alkenyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, C16 terminal olefin-derived alkenyl succinic anhydride, and tetrapropenyl succinic anhydride, and wherein the one or more second monomers are selected from one or more of diethanolamine, trimethyl-1,6-hexanediamine, isophorone diamine, poly(propylene glycol) bis(aminopropyl ether), Jeffamine ED-600, Jeffamine ED-900, and Jeffamine ED-2003. Preferably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of pimelic acid or an acid chloride or ester thereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride, and wherein the one or more second monomers are selected from one or more of diethanolamine, poly(propylene glycol) bis(aminopropyl ether), Jeffamine ED-600 and Jeffamine ED-2003. Preferably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of pimelic acid or an acid chloride or ester thereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride, and wherein the one or more second monomers are selected from one or more of diethanolamine, poly(propylene glycol) bis(aminopropyl ether), Jeffamine ED-600 and Jeffamine ED-2003. Preferably, the polymer may be the reaction product of monomers comprising a single (i.e. one) first monomer and a single (i.e. one) second monomer, wherein the first monomer is selected from pimelic acid or an acid chloride oresterthereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride, and wherein the second monomer is selected from diethanolamine, poly(propylene glycol) bis(aminopropyl ether), Jeffamine ED-600 and Jeffamine ED-2003. Preferably, the polymer may be the reaction product of monomers consisting essentially of or consisting of a single (i.e. one) first monomer and a single (i.e. one) second monomer, wherein the first monomer is selected from pimelic acid or an acid chloride or ester thereof, hydrogenated dimer acid or an acid chloride or ester thereof, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride, and wherein the second monomer is selected from diethanolamine, poly(propylene glycol) bis(aminopropyl ether), Jeffamine ED-600 and Jeffamine ED-2003. Preferably, the polymer may be the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride, C20-C24 alkenyl succinic anhydride, C15-18 internal olefinderived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, C16 terminal olefin-derived alkenyl succinic anhydride, and tetrapropenyl succinic anhydride, and wherein the one or more second monomers are selected from one or more of Jeffamine ED-600, Jeffamine ED-900, and Jeffamine ED-2003. Preferably, the polymer may be the reaction product of monomers consisting essentially of or consisting of one or more first monomers and one or more second monomers, wherein the one or more first monomers are selected from one or more of nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride, C20-C24 alkenyl succinic anhydride, C15-18 internal olefin-derived alkenyl succinic anhydride, C16 internal olefin-derived alkenyl succinic anhydride, C16 terminal olefin-derived alkenyl succinic anhydride, and tetrapropenyl succinic anhydride, and wherein the one or more second monomers are selected from one or more of Jeffamine ED-600, Jeffamine ED-900, and Jeffamine ED-2003. Preferably, the polymer is the reaction product of monomers comprising: (i) Pimelic acid or an acid chloride or ester thereof and diethanolamine, preferably in a molar ratio of 1:1; (ii) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Cs-24 alkenyl group and / or an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; (iii) Hydrogenated dimer acid or an acid chloride or ester thereof and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; or (iv) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group and / or an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and a diamine selected from isophorone diamine and trimethyl-1,6-hexanediamine, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers consisting essentially of or consisting of: (i) Pimelic acid or an acid chloride or ester thereof and diethanolamine, preferably in a molar ratio of 1:1; (ii) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group and / or an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; (iii) Hydrogenated dimer acid or an acid chloride or ester thereof and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; or (iv) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group and / or an alkenyl group derived from a terminal olefin or an internal olefin, preferably an internal olefin) and a diamine selected from isophorone diamine and trimethyl-1,6-hexanediamine, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers comprising: (i) pimelic acid or an acid chloride or ester thereof and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers consisting essentially of or consisting of: (i) pimelic acid or an acid chloride or ester thereof and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers comprising: (i) pimelic acid or an acid chloride or ester thereof and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers consisting essentially of or consisting of (i) pimelic acid or an acid chloride or ester thereof and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers comprising: (i) Pimelic acid and diethanolamine, preferably in a molar ratio of 1:1; (ii) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group) and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; (iii) Hydrogenated dimer acid and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; or (iv) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group) and a diamine selected from isophorone diamine and trimethyl-1,6-hexanediamine, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers consisting essentially of or consisting of: (i) Pimelic acid and diethanolamine, preferably in a molar ratio of 1:1; (ii) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group) and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; (iii) Hydrogenated dimer acid and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1; or (iv) Cyclic anhydride of formula (I) wherein one of R1 and R2 is hydrogen and the other is an alkenyl group (such as a Ca-24 alkenyl group) and a diamine selected from isophorone diamine and trimethyl-1,6-hexanediamine, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers comprising: (i) pimelic acid and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers consisting essentially of or consisting of: (i) pimelic acid and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and a polyether diamine, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and a monomer of the formula (IVA) as defined herein, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers comprising: (i) pimelic acid and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers consisting essentially of or consisting of: (i) pimelic acid and diethanolamine, preferably in a molar ratio of 1:1; (ii) (2-dodecen-1-yl)succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; (iii) octadecenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1; or (iv) C20-C24 alkenyl succinic anhydride and Jeffamine ED-2003, preferably in a molar ratio of 1:1. Preferably, the polymer is the reaction product of monomers comprising, consisting essentially of or consisting of pimelic acid and diethanolamine, preferably in a molar ratio of 1:1. Jeffamine ED-2003 is commercially available from Huntsman and is a polyetheramine that is derived from propylene oxide capped polyethylene glycol and that is of formula (V): U y | s CHs                CHs (V) wherein y = 39 and (x + z = 6). Jeffamine ED-900 is also commercially available from Huntsman and is of formula (V) except that y = 12.5 and (x + z) = 6. Jeffamine ED-600 is also commercially available from Huntsman and is of formula (V) except that y = 9 and (x + z) = 3.6. The polymer formed from the first, second and optional third monomers may comprise a suitable number of total monomer units (i.e. repeat units). For example, the polymer may comprise at least 4 monomer units. In other words, the polymer may comprise a total of at least 4 monomer units including the first, second and optional third monomers. Suitably, the polymer may comprise from 4 to 50 monomer units, preferably from 4 to 30 monomer units. Suitably, the polymer has a number average molecular weight of from 1,000 to 50,000 Daltons, preferably from 1,000 to 15,000 Daltons (for example from 2,000 to 7,000 or from 2,000 to 3,000 Daltons). Suitably, the polymer has a polydispersity index of from 1 to 4, such as from 1.1 to 2, preferably from 1.5 to 1.6. The polydispersity index of a polymer is given by the ratio of Mw to Mn (Mw / Mn), wherein Mw is the weight-average molecular weight and Mn is the number average molecular weight. In some embodiments, the nitrogen containing compound is not a polymer. For example, the nitrogen containing compound may comprise a single residue of the first reactant and a single residue of the second reactant, or two residues of the first reactant and a single residue of the second reactant, or a single residue of the first reactant and two residues of the second reactant. The nitrogen containing compound may comprise a single residue of a cyclic anhydride of formula (I) and a single residue of a monomer of formula (IVA), and have the structure: wherein R1 and R2 are as defined in relation to formula (I) herein and R20 and n6 are as defined in relation to formula (IVA) herein. The nitrogen containing compound may comprise two residues of a cyclic anhydride of formula (I) and a single residue of a monomer of formula (IVA), and have the structure: wherein R1 and R2 are as defined in relation to formula (I) herein and R20 and n6 are as defined in relation to formula (IVA) herein. Preferably, the polymer is substantially free of silicon atoms. By substantially free of silicon atoms we mean that the polymer contains less than 1 wt% of silicon in the polymer, preferably less than 0.5 wt% of silicon in the polymer. More preferably, the polymer is free of silicon atoms, by which we mean that it is not possible to detect silicon in the polymer. Suitable methods of measuring the amount of silicon in a polymer are well known to those skilled in art and include elemental analysis and inductively coupled plasma (ICP) spectroscopy. Preferably, the polymer is substantially free of fluorine atoms. The polymer may be substantially free of halogen atoms. By substantially free of fluorine or halogen atoms we mean that the polymer contains less than 1 wt% of fluorine or halogen in the polymer, preferably less than 0.5 wt% of fluorine or halogen in the polymer. More preferably, the polymer is free of fluorine atoms. The polymer may be free of halogen atoms. By free of fluorine or halogen atoms we mean that it is not possible to detect fluorine or halogen in the polymer. Suitable methods of measuring the amount of fluorine or halogen in a polymer are well known to those skilled in art and include elemental analysis and inductively coupled plasma (ICP) spectroscopy. Preferably, the polymer is substantially free of quaternary ammonium moieties. By substantially free of quaternary ammonium moieties we mean that the polymer contains less than 1 wt% of quaternary nitrogen atoms in the polymer, preferably less than 0.5 wt% of quaternary nitrogen atoms in the polymer. More preferably, the polymer is free of quaternary ammonium moieties, by which we mean that it is not possible to detect quaternary ammonium moieties in the polymer. According to a second aspect of the invention, there is provided a concentrate composition comprising one or more nitrogen containing compounds and optionally at least one solvent, wherein the concentrate composition comprises at least 20 wt% of the one or more nitrogen containing compounds, and wherein the or each nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. According to the second aspect of the invention, there may be provided a concentrate composition comprising one or more polymers and optionally at least one solvent, wherein the concentrate composition comprises at least 20 wt% of the one or more polymers, and wherein the or each polymer is the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is a polycarboxylic acid or a reactive equivalent thereof and the or each second monomer is a polyfunctional monomer having at least one reactive amino group. The concentrate composition may comprise at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of the one or more nitrogen containing compounds (preferably the polymers) based on the total weight of the concentrate composition. The concentrate composition additionally may comprise 99 wt% or less, such as 95 wt% or less, for example 90 wt% or less of the one or more nitrogen containing compounds (preferably the polymers) based on the total weight of the concentrate composition. The concentrate composition may comprise from 20 to 99 wt%, preferably from 20 to 95 wt%, for example from 50 to 90 wt%, of the one or more nitrogen containing compounds (preferably the polymers) based on the total weight of the concentrate composition. References herein to the amount of nitrogen containing compound (or polymer) in the concentrate composition are intended to refer to the total of the or each nitrogen containing compound (or polymer) as defined herein that is included in the composition, i.e. based on the total weight of the concentrate composition. Suitably, the concentrate composition may be stable for at least 1 week, preferably at least 4 weeks, most preferably at least 8 weeks under ambient conditions (for example, at atmospheric pressure and at a temperature of 20°C). The stability of the concentrate composition may be determined visually. Suitably, the concentrate composition is unstable when it shows creaming, sedimentation, separation, ora combination thereof. Suitably, the concentrate composition may comprise at least 20 wt%, such as at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of the one or more polymers and the concentrate composition may be stable for at least 1 week, preferably at least 4 weeks or at least 8 weeks, most preferably at least 3, 6, 12 or 24 months, under ambient conditions. Suitably, the concentrate composition may be flowable. The meaning of a “flowable” composition is well known to those skilled in the art. Typically, flowable compositions are pourable from a container at 20°C. Flowable compositions may be poured without needing to heat the composition above 20°C or manually scraping the composition. Suitably, the concentrate composition may have a viscosity of 7,000 cP or less, preferably 3,500 cP or less at 20°C. Suitably, the concentrate composition may comprise at least 20 wt%, such as at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of the nitrogen containing compound (preferably the polymer) and the concentrate composition may be flowable. Suitably the concentrate composition of the second aspect is substantially free of silicon atoms. By substantially free of silicon atoms we mean that the composition contains less than 1 wt%, preferably less than 0.5 wt%, of silicon in the composition. More preferably, the composition is free of silicon atoms, by which we mean that it is not possible to detect silicon in the composition. Suitable methods of measuring the amount of silicon in a composition are well known to those skilled in art and include elemental analysis and inductively coupled plasma (ICP) spectroscopy. The nitrogen containing compound (preferably the polymer) referred to in relation to the second aspect may comprise the reaction product of reactants (preferably monomers) comprising one or more first reactants (preferably first monomers), one or more second reactants (preferably second monomers) and optionally one or more third reactants (preferably third monomers) as defined herein. The nitrogen containing compound (preferably the polymer) referred to in relation to the second aspect may be the reaction product of reactants (preferably monomers) consisting essentially of or consisting of one or more first reactants (preferably first monomers), one or more second reactants (preferably second monomers) and optionally one or more third reactants (preferably third monomers) as defined herein. Features of the nitrogen containing compound (preferably the polymer), and of the first and second reactants (and the third reactants when present) (preferably the first, second, and third monomers, respectively), in relation to the second aspect of the invention are as set out herein in relation to the first aspect of the invention. In particular, the nitrogen containing compound is preferably a polymer. The reactants are preferably monomers. The one or more first reactants are preferably one or more first monomers, the one or more second reactants are preferably one or more second monomers, and the polyfunctional reactant is preferably a polyfunctional monomer having at least one reactive amino group. Preferably, the concentrate composition comprises a polymer that is the reaction product of monomers comprising, consisting essentially of, or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is a dicarboxylic acid or an acid chloride or ester thereof; and wherein the or each second monomer is one or more polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group. The concentrate composition of the second aspect may optionally comprise any suitable solvent, such as for example a polar solvent, such as a polar protic solvent. Preferably, the concentrate composition comprises at least one solvent. The solvent may be an aqueous solvent. Thus, the concentrate composition may be an aqueous composition. The term “aqueous solvent” herein is considered to mean water or mixtures of water and at least one water miscible solvent. Water miscible solvents may include alcohols and substantially water-miscible organic solvents. Preferably the aqueous solvent is water. When the solvent is an aqueous solvent, the concentrate composition may be in the form of an emulsion. The solvent may be a non-aqueous solvent. The non-aqueous solvent suitably comprises an organic solvent, such as an alcohol. The non-aqueous solvent preferably does not comprise any surfactant. Suitable such alcohols for use in the solvent include monohydric alcohols, polyhydric alcohols, alkoxy alcohols and aryloxy alcohol. Suitable alcohols are monohydric alcohols, polyhydric alcohols and alkoxy alcohols. Preferred alcohols are miscible with water. Suitable simple monohydric alcohols include methanol, ethanol, isopropanol and butanol. The solvent may comprise a polyhydric alcohol or an alkoxyalcohol. Suitable alkoxy alcohols include diethylene glycol monobutyl ether, 3-methoxy-3-methyl-1-butanol and 2-butoxyethanol. Suitable aryloxy alcohols include 2-phenoxyethanol. Suitable polyhydric alcohols include glycerol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol and 2-methylpentanediol. Suitable polyhydric alcohols include glycerol, ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol and polypropylene glycol. Preferably, the non-aqueous solvent comprises a monohydric alcohol such as isopropanol. The concentrate composition may comprise at least 20 wt%, at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt% or at least 70 wt% of the at least one solvent (when present) based on the total weight of the concentrate composition. The concentrate composition additionally may comprise 80 wt% or less, such as 70 wt% or less, of the at least one solvent (when present) based on the total weight of the concentrate composition. The concentrate composition may comprise from 20 to 80 wt%, preferably from 20 to 75 wt%, such as from 50 to 80 wt% or from 50 to 75 wt%, of the at least one solvent (when present) based on the total weight of the concentrate composition. The concentrate composition of the second aspect may additionally comprise one or more surfactants (in particular when the solvent is an aqueous solvent). Preferably, the concentrate composition of the second aspect comprises one or more surfactants (in particular when the solvent is an aqueous solvent). Any suitable surfactant(s) may be included, such as for example one or more surfactants selected from anionic surfactants, cationic surfactants, non-ionic surfactants, and amphoteric or zwitterionic surfactants. One or more non-ionic surfactant(s) are preferred. The concentrate composition may comprise an anionic surfactant. Suitable anionic surfactants may include sulfate surfactants (such as mono- or di-alkyl sulfates or alkyl ether sulfates), sulfonate surfactants, alkyl ether carboxylate surfactants, sarcosinate surfactants, phosphate surfactants, succinate surfactants, sulfosuccinate surfactants, sulfoacetate surfactants, isethionate surfactants, taurate surfactants, amino acid surfactants such as glutamates and glycinates, lactylate surfactants, and fatty acid salts. Particularly exemplary salts of the above, where applicable, are the sodium, potassium, ammonium, magnesium and triethanolamine salts. The concentrate composition may comprise a cationic surfactant. The cationic surfactant may be an ammonium salt such as an alkyl trimethyl ammonium salt, a dialkyl dimethyl ammonium salt, an alkyl-(N-hydroxyethyl)-dimethyl ammonium salt, or an alkyldimethylbenzylammonium salt (i.e. a benzalkonium salt). The salt may be a halide, hydroxide, sulfate, hydrogensulfate, phosphate, or carboxylate salt. The salt is suitably a halide salt, such as a fluoride, chloride, or bromide salt. The salt may be a carboxylate salt, such as formate or acetate salt. Preferably, the salt is chloride. The concentrate composition may comprise a non-ionic surfactant. Suitable non-ionic surfactants for use herein include castor oil, alcohol alkoxylates (such as alcohol ethoxylates, alcohol propoxylates, and ethylene oxide / propylene oxide copolymer derived surfactants), aliphatic esters, aromatic esters, sugar esters (such as sorbitan esters), alkyl (poly)glycosides, fatty acid alkoxylates (such as fatty acid ethoxylates and fatty acid propoxylates), or polyethylene glycol esters (including partial esters), glycerol esters (including glycerol partial esters and glycerol triesters), fatty alcohols (such as cetearyl alcohol, lauryl alcohol, stearyl alcohol, behenyl alcohol), alkanolamides, fatty amine alkoxylates (such as fatty amine ethoxylates and fatty amine propoxylates), and polyglyceryl fatty acid esters. Suitable non-ionic surfactants for use herein include alcohol alkoxylates (such as alcohol ethoxylates, alcohol propoxylates, and ethylene oxide / propylene oxide copolymer derived surfactants), aliphatic esters, aromatic esters, sugar esters (such as sorbitan esters), alkyl (poly)glycosides, fatty acid alkoxylates (such as fatty acid ethoxylates and fatty acid propoxylates), or polyethylene glycol esters (including partial esters), glycerol esters (including glycerol partial esters and glycerol triesters), fatty alcohols (such as cetearyl alcohol, lauryl alcohol, stearyl alcohol, behenyl alcohol), and alkanolamides. Preferably, the non-ionic surfactant may be selected from one or more of a sugar ester (such as a sorbitan ester) and a fatty amine alkoxylate (such as a fatty amine ethoxylate or fatty amine propoxylate). Suitable sugar esters may include alkoxylated (such as ethoxylated) sugar esters. For example, the sugar ester may comprise an alkoxylated (such as ethoxylated) sugar ester of a fatty acid, such as oleic acid. An example of a preferred sugar ester surfactant is Tween® 80. Suitable fatty amine alkoxylates may include fatty amine ethoxylates and fatty amine propoxylates. Fatty amine ethoxylates are preferred. The fatty amine alkoxylates may be based on any suitable fatty alcohol. An example of a preferred fatty amine alkoxylate is a fatty amine ethoxylate such as Empilan® AMT 11, which is a fatty amine ethoxylate containing 11 moles of ethylene oxide. The concentrate composition may comprise an amphoteric or zwitterionic surfactant. The amphoteric or zwitterionic surfactant may be selected from betaines (such as alkyl betaines and alkylamidopropyl betaines), amphoacetates, diamphoacetates, and amine oxides (such as alkylamine oxides and alkylamidopropyl amine oxides). Suitable amphoteric or zwitterionic surfactants include lauryl betaine, cocamidopropyl betaine, sodium lauroamphoacetate, sodium cocoamphoacetate, disodium cocoamphodiacetate, lauramine oxide, C12-18 alkyldimethylamine oxide, myristamine oxide, and cocamidopropyl amine oxide. The one or more surfactants may be selected from a fatty alkyl amphoacetate (for example cocoyl amphoacetate, lauryl amphoacetate), an alkyl (poly)glycoside (for example lauryl glycoside), an acyl glycinate (for example cocoyl glycinate), a sulfosuccinate, an amphodiacetate and a fatty alcohol ether carboxylate (for example C8-12 alkyl ether (6-11 moles EO) carboxylate). The concentrate composition may comprise at least 1 wt%, at least 3 wt%, at least 5 wt%, of the one or more surfactants (when present) based on the total weight of the concentrate composition. The concentrate composition additionally may comprise 15 wt% or less, such as 10 wt% or less, of the one or more surfactants (when present) based on the total weight of the concentrate composition. The concentrate composition may comprise from 1 to 15 wt%, preferably from 3 to 10 wt% of the one or more surfactants (when present) based on the total weight of the concentrate composition. The concentrate composition of the second aspect may comprise the one or more surfactants in an amount of from 1 to 100 wt%, suitably from 5 to 50 wt%, preferably from 5 to 25 wt% or from 10 to 25 wt% based on the total weight of the one or more nitrogen containing compounds (preferably the polymers). When the concentrate composition comprises the one or more nitrogen containing compounds (preferably the polymers), the at least one solvent and the one or more surfactants, the composition may comprise: (i) from 20 to 60 wt% of the one or more nitrogen containing compounds (preferably the polymers); (ii) from 35 to 60 wt% of the at least one solvent; and (iii) from 1 to 15 wt% of the one or more surfactants; based on the total weight of the concentrate composition. When the concentrate composition comprises the one or more nitrogen containing compounds (preferably the polymers), the at least one solvent and the one or more surfactants, the composition may comprise: (i) from 20 to 45 wt% of the one or more nitrogen containing compounds (preferably the polymers); (ii) from 50 to 75 wt% of the at least one solvent; and (iii) from 1 to 15 wt% of the one or more surfactants; based on the total weight of the concentrate composition. When the concentrate composition comprises the one or more nitrogen containing compounds (preferably the polymers), the at least one solvent and the one or more surfactants, the composition may comprise: (i) from 20 to 40 wt% of the one or more nitrogen containing compounds (preferably the polymers); (ii) from 50 to 75 wt% of the at least one solvent; and (iii) from 3 to 10 wt% of the one or more surfactants; based on the total weight of the concentrate composition. According to a third aspect of the invention, there is provided a use of a surfactant to emulsify at least one nitrogen containing compound in an aqueous concentrate composition, wherein the aqueous concentrate composition comprises at least 20 wt% of the one or more nitrogen containing compounds, and wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. According to the third aspect of the invention, there may be provided a use of a surfactant to emulsify at least one polymer in an aqueous concentrate composition, wherein the concentrate composition comprises at least 20 wt% of the one or more polymers, and wherein the polymer is the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is a polycarboxylic acid or a reactive equivalent thereof and the or each second monomer is a polyfunctional monomer having at least one reactive amino group. The nitrogen containing compound (preferably the polymer) referred to in relation to the third aspect may comprise the reaction product of reactants (preferably monomers) comprising one or more first reactants (preferably first monomers), one or more second reactants (preferably second monomers) and optionally one or more third reactants (preferably third monomers) as defined herein. The nitrogen containing compound (preferably the polymer) referred to in relation to the third aspect may be the reaction product of reactants (preferably monomers) consisting essentially of or consisting of one or more first reactants (preferably first monomers), one or more second reactants (preferably second monomers) and optionally one or more third reactants (preferably third monomers) as defined herein. Features of the nitrogen containing compound (preferably the polymer), and of the first and second reactants (and the third reactants when present) (preferably the first, second, and third monomers, respectively), in relation to the third aspect of the invention are as set out herein in relation to the first aspect of the invention. Features of the surfactant in relation to the third aspect of the invention are as set out herein in relation to the second aspect of the invention. In particular, the nitrogen containing compound is preferably a polymer. The reactants are preferably monomers. The one or more first reactants are preferably one or more first monomers, the one or more second reactants are preferably one or more second monomers, and the polyfunctional reactant is preferably a polyfunctional monomer having at least one reactive amino group. Preferably, the aqueous concentrate composition comprises a polymer that is the reaction product of monomers comprising, consisting essentially of, or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is a dicarboxylic acid or an acid chloride or ester thereof; and wherein the or each second monomer is one or more polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group. According to a fourth aspect of the invention, there is provided a method of emulsifying at least one nitrogen containing compound in an aqueous composition to make an aqueous concentrate composition, wherein the aqueous concentrate composition comprises at least 20 wt% of the one or more nitrogen containing compounds, the method comprising admixing a surfactant with the nitrogen containing compound in an aqueous composition, wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group. According to the fourth aspect of the invention, there may be provided a method of emulsifying at least one polymer in an aqueous composition to make an aqueous polymer concentrate composition, wherein the aqueous polymer concentrate composition comprises at least 20 wt% of the one or more polymers, and the method comprising admixing a surfactant with the polymer in the aqueous composition, wherein the polymer is the reaction product of monomers comprising one or more first monomers and one or more second monomers, wherein the or each first monomer is a polycarboxylic acid or a reactive equivalent thereof and the or each second monomer is a polyfunctional monomer having at least one reactive amino group. The nitrogen containing compound (preferably the polymer) referred to in relation to the fourth aspect may comprise the reaction product of reactants (preferably monomers) comprising one or more first reactants (preferably first monomers), one or more second reactants (preferably second monomers) and optionally one or more third reactants (preferably third monomers) as defined herein. The nitrogen containing compound (preferably the polymer) referred to in relation to the fourth aspect may be the reaction product of reactants (preferably monomers) consisting essentially of or consisting of one or more first reactants (preferably first monomers), one or more second reactants (preferably second monomers) and optionally one or more third reactants (preferably third monomers) as defined herein. Features of the nitrogen containing compound (preferably the polymer), and of the first and second reactants (and the third reactants when present) (preferably the first, second, and third monomers, respectively), in relation to the fourth aspect of the invention are as set out herein in relation to the first aspect of the invention. Features of the surfactant in relation to the fourth aspect of the invention are as set out herein in relation to the second aspect of the invention. In particular, the nitrogen containing compound is preferably a polymer. The reactants are preferably monomers. The one or more first reactants are preferably one or more first monomers, the one or more second reactants are preferably one or more second monomers, and the polyfunctional reactant is preferably a polyfunctional monomer having at least one reactive amino group. Preferably, the aqueous concentrate composition comprises a polymer that is the reaction product of monomers comprising, consisting essentially of, or consisting of one or more first monomers and one or more second monomers, wherein the or each first monomer is a dicarboxylic acid or an acid chloride or ester thereof; and wherein the or each second monomer is one or more polyfunctional monomer comprising at least one reactive amino group and at least one hydroxyl group. Examples The invention will now be further described with reference to the following non-limiting examples. Example 1 - synthesis of polymers containing both ester and amide groups The polycarboxylic acid or anhydride (monomer 1) were combined with the amine-containing monomer (monomer 2). Tin(ll) ethylhexanoate (0.5 wt% relative to the total weight of monomers) was added. The reaction mass was heated at 160°C for 6 hours. The resulting polymer was decanted from the reaction flask, and no further purification was carried out. Polymers 1 to 3 were prepared according to Example 1, using the monomers and reaction stoichiometries as set out in Table 1. Example 2 - synthesis of polyamides The polycarboxylic acid or anhydride (monomer 1) were combined with the amine-containing monomer (monomer 2) and heated at 225°C for 6 hours. The resulting polyamide was decanted from the reaction flask. No further purification was carried out. Polyamides 4 to 22 were prepared according to Example 2, using the monomers and reaction stoichiometries as set out in Table 1. Table 1 Polymer Monomer 1 (Polycarboxylic acid or cyclic anhydride) Monomer 2 (amine) Molar ratio of monomers 1 Sebacic acid Diethanolamine 1 : 1 2 Pimelic acid Diethanolamine 1 : 1 3 Octadecenyl succinic anhydride Diethanolamine 1 : 1 4 Dodecanedioic acid Jeffamine ED-2003 1 : 1 5 Nonenyl succinic anhydride Jeffamine ED-2003 1 : 1 6 (2-Dodecen-1 -yl)succinic anhydride Jeffamine ED-2003 1 : 1 7 Octadecenyl succinic anhydride Jeffamine ED-2003 1 : 1 8 C20-24 ASA Jeffamine ED-2003 1 : 1 9 (2-Dodecen-1 -yl)succinic anhydride Jeffamine ED-600 1 : 1 10 (2-Dodecen-1 -yl)succinic anhydride Trimethyl-1,6-hexanediamine 1 : 1 11 Hydrogenated dimer acid Jeffamine ED-600 1 : 1 12 Nonenyl succinic anhydride Polypropylene glycol) bis(aminopropyl)ether Mw~230 Da 1 : 1 13 (2-Dodecen-1 -yl)succinic anhydride Polypropylene glycol) bis(aminopropyl)ether Mw~230 Da 1 : 1 14 Octadecenyl succinic anhydride Polypropylene glycol) bis(aminopropyl)ether Mw~230 Da 1 : 1 15 Hydrogenated dimer acid Polypropylene glycol) bis(aminopropyl)ether Mw~230 Da 1 : 1 16 Octadecenyl succinic anhydride Isophorone diamine 1 : 1 17 Nonenyl succinic anhydride Jeffamine ED-600 1 : 1 18 (2-Dodecen-1 -yl)succinic anhydride Jeffamine ED-900 1 : 1 19 Hydrogenated dimer acid Jeffamine ED-2003 1 : 1 20 C16 IO ASA Jeffamine ED-2003 1 : 1 21 C16TO ASA Jeffamine ED-2003 1 : 1 22 Tetrapropenyl succinic anhydride Jeffamine ED-2003 1 : 1 Table 2 - abbreviations and chemical names C20-24 ASA C20-C24 alkenyl succinic anhydride Jeffamine ED-2003 Polyether diamine comprising ethylene oxide and propylene oxide derived repeat units and having Mn ~ 2,000. Commercially available from Huntsman Corporation (Texas, United States) Jeffamine ED-600 Polyether diamine having Mn ~ 600 as defined herein. Commercially available from Huntsman Corporation (Texas, United States) Jeffamine ED-900 Polyether diamine having Mn ~ 900 as defined herein. Commercially available from Huntsman Corporation (Texas, United States) C16 IO ASA C16 internal olefin-derived alkenyl succinic anhydride: a substituted succinic anhydride obtained by the reaction of maleic anhydride and a C16 internal olefin C16TO ASA C16 terminal olefin-derived alkenyl succinic anhydride: a substituted succinic anhydride obtained by the reaction of maleic anhydride and a C16 terminal olefin Example 3 - Preparation of further concentrated aqueous emulsions. A polymer (20 wt%), surfactant (5 wt% active unless otherwise indicated in Table 3) and deionized water (balance, i.e. 75 wt% when surfactant is 5 wt%) were combined with a vortex mixer. The resulting mixture was left to stand at ambient temperature and the emulsion quality overtime was observed. The results are shown in Table 3. If the resulting mixture formed a stable emulsion, this is entered as “Stable”. If recorded as “Stable”, the stability time indicates the last time-point which was assessed. If the polymer dissolved, this is entered as “Soluble”. If recorded as “Soluble”, the stability time indicates the last time-point which was assessed. Table 3 Polymer Surfactant Amount of surfactant (wt% active) Result Stability time 2 Tween 80* 5 Stable 7 months 2 Tallow amine ethoxylate (11 EO) 5 Soluble 3 months * Tween 80 is an ethoxylated sorbitan ester based on a natural fatty acid (oleic acid) commercially available from Croda International Plc (Goole, UK). Unless otherwise stated herein, the reference to “liquid”, “gel” and “solid” refer to a state at 25 °C and standard pressure (101,325 Pa). Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A nitrogen containing compound, wherein the nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a polycarboxylic acid or a reactive equivalent thereof and the or each second reactant is a polyfunctional reactant having at least one reactive amino group.

2. The nitrogen containing compound according to claim 1, wherein the nitrogen containing compound is a polymer, the reactants are monomers, the one or more first reactants are one or more first monomers, the one or more second reactants are one or more second monomers, and the polyfunctional reactant is a polyfunctional monomer having at least one reactive amino group.

3. The nitrogen containing compound according to claim 2, wherein the polymer is a polyamide.

4. The nitrogen containing compound according to claim 2 or claim 3, wherein the or each first monomer is a cyclic anhydride selected from one or more of formula (I), of formula (II) and of formula (III):wherein in formula (I) R1 and R2 are each independently selected from hydrogen, an alkyl group and an alkenyl group, or R1 and R2 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group;in formula (II) R3 and R4 are each independently selected from hydrogen, an alkyl group and an alkenyl group, or R3 and R4 together with the carbon atoms to which they are attached represent an optionally substituted cyclic group; andin formula (III) X is CR9R10, O, S, or NR11; R5, R6, R7, R8, R9, R10, and R11 are each independently selected from hydrogen, an alkyl group and an alkenyl group, and / or any of R5, R6, R7, R8, R9, R10, and R11 together with the atoms to which they are attached represent anoptionally substituted cyclic group; or a polycarboxylic acid or an acid chloride or ester thereof, wherein the polycarboxylic acid is selected from:a polycarboxylic acid of the formula HOOC(CR2)nCOOH, wherein n is from 0 to 30; and each R is independently hydrogen or a substituent; and / or two R groups on the same carbon atom are taken together to form a methylene (=CH2) group; and / or when n is two or more, two R groups on adjacent carbon atoms are taken together to form a double bond; and n is suitably from 1 to 20, preferably from 2 to 16, more preferably from 2 to 12, for example from 2 to 10;a polycarboxylic acid of the formula HOOC(CH2)mX1(CH2)m2COOH, wherein m+m2 is from 0 to 30 and X1 is O, S, or NR17 wherein R17 is hydrogen or a hydrocarbyl group;a polycarboxylic acid of the formula HOOCCH2(OCH2CHR18)XOCH2COOH, wherein x is from 1 to 30 and each R18 is independently hydrogen or a hydrocarbyl group;a polycarboxylic acid comprising a cyclic group; or a dimer acid.

5. The nitrogen containing compound according to any of claims 2 to 4, wherein the or each first monomer is a cyclic anhydride selected from one or more of succinic anhydride, maleic anhydride, glutaric anhydride, a C6-30 alkenyl succinic anhydride such as C20-24 alkenyl succinic anhydride, dodecenyl succinic anhydride (such as (2-dodecen-1-yl)succinic anhydride), nonenyl succinic anhydride, octadecenyl succinic anhydride, octenyl succinic anhydride, octadecyl succinic anhydride, or octyl succinic anhydride, a branched alkenyl succinic anhydride such as tetrapropenyl succinic anhydride or polyisobutenyl succinic anhydride, phthalic anhydride, pyromellitic dianhydride, 1,2,4-benzenetricarboxylic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride and homophthalic anhydride; or a polycarboxylic acid or an acid chloride or ester thereof selected from oxalic acid, succinic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, maleic acid, malic acid, tartaric acid, citric acid, 1,4-cyclohexanedicarboxylic acid, isophthalic acid, terephthalic acid, diglycolic acid, thiodiglycolic acid, poly(ethylene glycol)bis(carboxymethyl) ether, a hydrogenated dimer acid or an acid chloride or ester thereof.

6. The nitrogen containing compound according to any of claims 2 to 5, wherein the or each first monomer is selected from one or more of sebacic acid, dodecanedioic acid, pimelic acid, hydrogenated dimer acid, nonenyl succinic anhydride, (2-dodecen-1-yl)succinic anhydride, octadecenyl succinic anhydride and C20-C24 alkenyl succinic anhydride.

7. The nitrogen containing compound according to any of claims 2 to 6, wherein the polyfunctional monomer comprises at least two reactive groups that reacts with the first monomer, wherein at least one of the reactive groups is the reactive amino group.

8. The nitrogen containing compound according to any of claims 2 to 7, wherein the polyfunctional monomer comprises at least two reactive amino groups.

9. The nitrogen containing compound according to any of claims 2 to 8, wherein the polyfunctional monomer is selected from ethanolamine, diethanolamine, ethylene diamine, coco propylene diamine, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), trimethyl-1,6-hexane diamine, isophorone diamine or a polyether diamine (preferably polypropylene glycol bis(aminopropyl) ether with MW around 230Da, Jeffamine ED-600, Jeffamine ED-900, or Jeffamine ED-2003).

10. The nitrogen containing compound according to any of claims 2 to 9, wherein the polyfunctional monomer is selected from ethylene diamine, coco propylene diamine, diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), trimethyl-1,6-hexane diamine, isophorone diamine or a polyether diamine (preferably polypropylene glycol bis(aminopropyl) ether with MW around 230Da, Jeffamine ED-600, Jeffamine ED-900, or Jeffamine ED-2003).

11. The nitrogen containing compound according to any of claims 2 to 10, wherein the polymer comprises at least 4 monomer units.

12. The nitrogen containing compound according to any of claims 2 to 11, wherein the polymer has a number average molecular weight of from 1,000 to 50,000 Daltons, preferably from 1,000 to 15,000 Daltons (for example from 2,000 to 7,000 Daltons).

13. The nitrogen containing compound according to any of claims 2 to 12, wherein the polymer is substantially free of silicon atoms.

14. A concentrate composition comprising one or more nitrogen containing compounds and optionally at least one solvent, wherein the concentrate composition comprises at least 20 wt% of the one or more nitrogen containing compounds, and wherein the or each nitrogen containing compound is the reaction product of reactants comprising one or more first reactants and one or more second reactants, wherein the or each first reactant is a cyclic anhydride and the or each second reactant is a polyfunctional reactant having at least one reactive amino group.

15. The concentrate composition according to claim 14, wherein the composition comprises at least 30 wt%, at least 40 wt%, at least 50 wt%, at least 60 wt%, at least 70 wt%, or at least 80 wt% of one or more nitrogen containing compounds.

16. The concentrate composition according to claim 14 or 15, wherein the composition additionally comprises one or more surfactants.

17. The concentrate composition according to claim 16, wherein the one or more surfactants are independently selected from anionic surfactants, cationic surfactants, non-ionic surfactants, and amphoteric or zwitterionic surfactants (preferably non-ionic surfactants).

18. The concentrate composition according to claim 17, wherein the one or more surfactants are independently selected from one or more of a sugar ester (such as a sorbitan ester) and a fatty amine alkoxylate (such as a fatty amine ethoxylate or fatty amine propoxylate).

19. The concentrate composition according to any of claims 14 to 18, wherein the concentrate composition is stable for at least 3, 6, 12 or 24 months under ambient conditions.

20. The concentrate composition according to any of claims 14 to 19, wherein the concentrate composition is flowable.

21. The concentrate composition according to claim 20, wherein the concentrate composition has a viscosity of 7,000 cP or less, preferably 3,500 cP or less at 20°C.

22. The concentrate composition according to any of claims 14 to 21, wherein the nitrogen containing compound is a polymer, the reactants are monomers, the one or more first reactants are one or more first monomers, the one or more second reactants are one or more second monomers, and the polyfunctional reactant is a polyfunctional monomer having at least one reactive amino group.