Preparation of branched polydienes and branched polydiene copolymers

Abstract

A method for preparing a branched polymer, the method comprising: (i) preparing a multi-site initiator by reacting a polyalkenyl compound with an alkyllithium compound; (ii) introducing the multi-site initiator, a monomer, and a potassium alkoxide to form a polymerization mixture comprising a molar ratio of potassium to lithium greater than 0.150:1; and (iii) polymerizing the monomer to form a branched polymer.

Description

[Technical Field]

[0001] DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention provide branched polydienes and branched polydiene copolymers, as well as methods for preparing multifunctional polymers, and the use of branched polymers in the preparation of tire components. [Background technology]

[0002] Polydienes, such as poly(butadiene), and diene copolymers, such as poly(styrene-co-butadiene), are often produced using anionic polymerization techniques, whereby diene monomers, optionally together with copolymerizable monomers such as vinyl aromatics, are polymerized using anionic initiators. The use of anionic polymerization techniques offers several advantages, including the ability to control molecular weight, prepare relatively linear polymer chains, and functionalize polymer chains through chain termination reactions. Useful anionic initiators include alkyllithium compounds, such as n-butyllithium. Multifunctional initiators can be formed, for example, by reacting alkyllithium compounds with dialkenyl compounds, such as diisopropenylbenzene. Polymers prepared using multifunctional initiators have multiple reactive chain ends, which provides the ability to functionalize both ends of the polymer chain to form telechelic polymers. Summary of the Invention

[0003] One or more embodiments of the present invention provide a method for preparing a branched polymer, the method comprising: (i) preparing a multi-site initiator by reacting a polyalkenyl compound with an alkyllithium compound; (ii) introducing the multi-site initiator, monomers, and a potassium alkoxide to form a polymerization mixture comprising a molar ratio of potassium to lithium greater than 0.150:1; and (iii) polymerizing the monomers to form the branched polymer.

[0004] Another embodiment of the present invention provides a vulcanizable composition comprising: (i) a branched polymer prepared by reacting a polyalkenyl compound with an alkyllithium compound to provide a multi-site initiator, and introducing the multi-site initiator, monomers, and potassium alkoxide to form a polymerization mixture comprising a molar ratio of potassium to lithium greater than 0.150:1, and polymerizing the monomers to form the branched polymer; and (ii) silica; and a curing agent.

[0005] Yet another embodiment of the present invention provides a method for forming a vulcanizable composition, the method comprising: (i) providing a branched polymer prepared by preparing a multi-site initiator by reacting a polyalkenyl compound with an alkyllithium compound, and by introducing the multi-site initiator, monomer, and potassium alkoxide to form a polymerization mixture comprising a molar ratio of potassium to lithium of greater than 0.150:1, and polymerizing the monomer to form the branched polymer; (ii) providing silica; (iii) providing a curing agent; and (iv) mixing the branched polymer, silica, and curing agent to form a vulcanizable composition. DETAILED DESCRIPTION OF THE INVENTION

[0006] Embodiments of the present invention are based, at least in part, on the discovery of methods for preparing branched polydienes and branched diene copolymers. According to embodiments of the present invention, branched polymers are prepared by anionic polymerization of monomers using a multi-site initiator in the presence of a threshold amount of potassium alkoxide. While prior art attempts to prepare branched polymers by using multi-site initiators, such as those prepared by reacting 1,3-diisopropenylbenzene with alkyllithium compounds, it has been discovered that when polymerization occurs in the presence of a threshold amount of potassium alkoxide, an unexpectedly high degree of branching is achieved, as evidenced by viscoelastic properties. Aging of the initiator in the presence of a Lewis base has also been found to contribute to improved branching. As long as the polymer is prepared by anionic polymerization techniques, branching advantageously results in multiple polymer active ends (i.e., reactive ends), which allows for the preparation of multifunctional polymers.

[0007] Preparation of branched copolymers In one or more embodiments, branched polydienes and branched diene copolymers, sometimes referred to as branched polymers, are prepared by polymerizing diene monomers, optionally with vinyl aromatic monomers, using a multifunctional initiator in the presence of a threshold amount of potassium alkoxide. The multifunctional initiator is prepared by reacting an alkyl lithium with a polyalkenyl compound. In one or more embodiments, the multifunctional initiator is aged in a suitable solvent in the presence of a Lewis base prior to its use in polymerization.

[0008] Initiator Preparation and Aging As noted above, the initiator is prepared by combining a polyalkenyl compound with an alkyllithium compound in a solvent to form a reaction mixture in which the reactants and products are at least partially soluble. The initiator is then aged in a suitable solvent in the presence of a Lewis base.

[0009] In one or more embodiments, the polyalkenyl compound is a 1,3-dialkenylbenzene compound, such as 1,3-diisopropenylbenzene. In one or more embodiments, the alkyllithium compound is a butyllithium compound, such as n-butyllithium, t-butyllithium, and / or sec-butyllithium. In certain embodiments, sec-butyllithium is used.

[0010] The Lewis base may include any Lewis base that does not contain an active hydrogen atom, where the presence of an active hydrogen atom is determined by a Zerewitinoff test. Exemplary Lewis bases include oxolanylpropanes such as 2,2-bis(2-oxolanyl)propane (also known as 2,2-ditetrahydrofurylpropane), meso-2,2-ditetrahydrofurylpropane, DL-2,2-ditetrahydrofurylpropane, tetramethylethylenediamine, and mixtures thereof, and trialkylamines such as triethylamine.

[0011] The amount of alkyllithium compound reacted with the polyalkenyl compound may be quantified based on the molar ratio of lithium to alkenyl groups, i.e., the number of equivalents of lithium (i.e., moles of Li) associated with the alkyllithium compound relative to the number of equivalents of alkenyl groups in the polyalkenyl compound (e.g., the number of equivalents of isopropenyl groups in 1,3-diisopropenylbenzene). In one or more embodiments, the ratio of moles of Li associated with the alkyllithium to the number of equivalents of alkenyl groups associated with the polyalkenyl compound may be from about 0.05:1 to about 0.95:1, from about 0.2:1 to about 0.75:1 in other embodiments, and from about 0.3:1 to about 0.65:1 in other embodiments. When sec-butyllithium is reacted with 1,3-diisopropenylbenzene, about 0.1 to about 1.9 moles, or in another embodiment about 0.4 to about 1.5 moles, and in another embodiment about 0.6 to about 1.3 moles of sec-butyllithium are reacted per mole of 1,3-diisopropenylbenzene.

[0012] The synthesis of the initiator is carried out in a solvent in which the reactants and products are at least partially soluble. Useful solvents include, but are not limited to, hydrocarbons with low or relatively low boiling points, such as aromatic hydrocarbons, aliphatic hydrocarbons, and cycloaliphatic hydrocarbons. Non-limiting examples of aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, diethylbenzene, and mesitylene. Non-limiting examples of aliphatic hydrocarbons include n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, isopentane, isohexane, isopentane, isooctane, 2,2-dimethylbutane, petroleum ether, kerosene, and mineral spirits. Non-limiting examples of cycloaliphatic hydrocarbons include cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane. Mixtures of the above hydrocarbons can also be used.

[0013] As described above, the multi-site initiator formed by the reaction is aged in a suitable solvent (e.g., the reaction medium) in the presence of a Lewis base. In one or more embodiments, the Lewis base is present at the time of introduction of the reactants to the reaction mixture. In other embodiments, the Lewis base is introduced after synthesis of the multi-site initiator, and aging occurs after introduction of the Lewis base.

[0014] The amount of Lewis base introduced into the reaction mixture may be quantified based on the moles of Lewis base (e.g., 2,2-ditetrahydrofurylpropane) to the moles of lithium associated with the alkyllithium compound (i.e., the ratio of moles of Lewis base to moles of lithium). In one or more embodiments, the ratio of moles of Lewis base introduced into the reaction medium to moles of lithium introduced with the alkyllithium compound may be from about 0.05:1 to about 1:1, in other embodiments from about 0.1:1 to about 0.6:1, and in other embodiments from about 0.2:1 to about 0.45:1.

[0015] In one or more embodiments, initiator aging is carried out under an inert atmosphere at atmospheric conditions at temperatures of from about 0 to about 150°C, in other embodiments from about 25 to about 100°C, and in other embodiments from about 35 to about 60°C. In one or more embodiments, the initiator is aged for more than 1 minute, in other embodiments from more than 5 minutes, in other embodiments from more than 12 minutes, and in other embodiments from more than 20 minutes, before introducing the initiator to the monomers to be polymerized. In one or more embodiments, the initiator is aged for from about 1 to about 60 minutes, in other embodiments from about 5 to about 50 minutes, and in other embodiments from about 12 to about 45 minutes, before introducing the initiator to the monomers to be polymerized. The appropriate aging time is temperature dependent; that is, the time required to age the initiator decreases with increasing temperature. Similarly, the maximum amount of aging decreases with temperature. It should also be understood that the temperature dependence of the aging process may allow for longer storage times at lower temperatures. For example, it is contemplated that the initiator (ie, the combination of the polyalkenyl compound and the alkyllithium) can be stored at a temperature below 0° C., for a period of, for example, 24 hours.

[0016] Polymerization reaction The multi-site initiator, prepared as described above and optionally aged, is combined with the monomers to be polymerized, along with a solvent and a potassium alkoxide, to form a polymerization mixture in which the monomers and the resulting branched polymer are at least partially soluble. In one or more embodiments, the initiator and potassium alkoxide are also at least partially soluble in the polymerization mixture.

[0017] Generally speaking, the polymerization of monomers with an initiator proceeds via anionic polymerization techniques. The preparation of polymers using anionic polymerization techniques is generally known. The important mechanistic features of anionic polymerization are described in books (e.g., Hsieh, HL; Quirk, RP Anionic Polymerization: Principles and Practical Applications; Marcel Dekker: New York, 1996) and review articles (e.g., Hadjichristidis, N.; Pitsikalis, M. Pispas, S. Iatrou, H. Chem. Rev. 2001, 101(12), 3747-3792). Anionic initiators can advantageously produce polymers with reactive chain ends (e.g., living polymers) that can react with additional monomers for further chain growth or with certain functionalizing agents to give functionalized polymers before quenching. Polymers with reactive polymer chain ends are sometimes simply referred to as reactive polymers. As will be appreciated by those skilled in the art, these reactive polymers contain reactive chain ends, which are believed to be ionic, at which a reaction can occur between a functionalizing agent and the reactive chain end of the polymer, thereby imparting functionality or functional groups to the polymer chain end or allowing multiple polymers to be coupled together.

[0018] The polymerization mixture can be formed by introducing the various components in any order. For example, in one or more embodiments, the monomer and solvent can be mixed first, then the potassium alkoxide can be added to the mixture of the solvent and monomer, and then the aging initiator can be introduced into the mixture. In one or more embodiments, the initiator and potassium alkoxide are combined after aging. In other embodiments, the initiator (i.e., the polyalkenyl compound and the alkyllithium) is combined with the potassium alkoxide and then aged.

[0019] Monomer to be polymerized Monomers that can be anionically polymerized to form these polymers include conjugated diene monomers, which can optionally be copolymerized with other monomers, such as vinyl-substituted aromatic monomers. Examples of conjugated diene monomers include 1,3-butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 2-methyl-1,3-pentadiene, 3-methyl-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 2,4-hexadiene. Mixtures of two or more conjugated dienes may also be used for copolymerization. Examples of monomers copolymerizable with conjugated diene monomers include vinyl-substituted aromatic compounds such as styrene, p-methylstyrene, α-methylstyrene, and vinylnaphthalene.

[0020] The amount of initiator used may depend on the interplay of various factors (e.g., the type of initiator used, the purity of the components, the polymerization temperature, the desired polymerization rate and conversion, the desired molecular weight, and many other factors). In one or more embodiments, the amount of initiator used may be expressed as millimoles of initiator per weight of monomer. In one or more embodiments, the amount of initiator introduced into the polymerization mixture is from about 0.1 to about 100 mmol, or in other embodiments from about 0.2 to about 50 mmol, or in other embodiments from about 0.3 to about 15 mmol, of initiator per 100 grams of monomer in the polymerization mixture (i.e., the monomer to be polymerized).

[0021] potassium alkoxide In one or more embodiments, the potassium alkoxide is at least partially soluble in the polymerization mixture, where at least partially soluble refers to a solubility at or above which the potassium alkoxide is not visible in the mixture without magnification.

[0022] In one or more embodiments, potassium alkoxides are defined by the formula ROK, where R is a monovalent organic group. For example, R may be a hydrocarbyl group, such as, but not limited to, an alkyl group, a cycloalkyl group, an alkenyl group, a cycloalkenyl group, an aryl group, an aryl group, an aralkyl group, an alkaryl group, or an alkynyl group. In one or more embodiments, the cycloalkyl, cycloalkenyl, and aryl groups are non-heterocyclic groups. In one or more embodiments, the hydrocarbyl groups may contain from about 2 to about 20 carbon atoms, or in other embodiments, from about 4 to about 16 carbon atoms. In one or more embodiments, the hydrocarbyl groups may include substituted hydrocarbyl groups, which refers to hydrocarbyl groups in which one or more hydrogen atoms have been replaced with a substituent, such as a hydrocarbyl group. In one or more embodiments, these groups may contain from 1 (or the minimum number of carbon atoms appropriate to form the group) to about 20 carbon atoms. In one or more embodiments, the substituents forming the substituted hydrocarbyl groups are non-heterocyclic groups. In one or more embodiments, the hydrocarbyl group may or may not contain heteroatoms.

[0023] Examples of potassium alkoxide compounds useful in the practice of the present invention include potassium tert-amylate and potassium tert-butoxide.

[0024] As noted above, aspects of the present invention are based on the use of a threshold amount of potassium alkoxide to achieve advantageous amounts of branching. This amount of potassium alkoxide can be quantified relative to the amount of lithium introduced into the polymerization system as part of the initiator. In one or more embodiments, the amount of potassium alkoxide introduced into the system is quantified as the molar ratio of the moles of potassium associated with the potassium alkoxide to the moles of lithium associated with the initiator. In one or more embodiments, the molar ratio of potassium to lithium (i.e., moles of K to moles of Li) in the polymerization system is greater than 0.150:1, in other embodiments greater than 0.200:1, in other embodiments greater than 0.225:1, and in other embodiments greater than 0.250:1. In these or other embodiments, the molar ratio of potassium to lithium in the polymerization system can be from about 0.150:1 to about 0.700:1, in other embodiments from about 0.170:1 to about 0.550:1, in other embodiments from about 0.200:1 to about 0.500:1, in other embodiments from about 0.225:1 to about 0.450:1, and in other embodiments from about 0.250:1 to about 0.350:1.

[0025] Solvent for the polymerization mixture In one or more embodiments, suitable solvents include organic compounds that do not undergo polymerization or incorporation into growing polymer chains during polymerization of monomers in the presence of a catalyst. In one or more embodiments, these organic species are liquid at ambient temperature and pressure. In one or more embodiments, these organic solvents are inert to the catalyst. Exemplary organic solvents include hydrocarbons with low or relatively low boiling points, such as aromatic hydrocarbons, aliphatic hydrocarbons, and cycloaliphatic hydrocarbons. Non-limiting examples of aromatic hydrocarbons include benzene, toluene, xylene, ethylbenzene, diethylbenzene, and mesitylene. Non-limiting examples of aliphatic hydrocarbons include n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, isopentane, isohexane, isopentane, isooctane, 2,2-dimethylbutane, petroleum ether, kerosene, and mineral spirits. Non-limiting examples of cycloaliphatic hydrocarbons include cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane. Mixtures of the above hydrocarbons can also be used. The low-boiling hydrocarbon solvent is typically separated from the polymer when the polymerization is complete. Other examples of organic solvents include high-molecular-weight, high-boiling hydrocarbons, such as paraffinic oils, aromatic oils, or other hydrocarbon oils commonly used in oil-extended polymers. Because these hydrocarbons are non-volatile, they typically do not need to be separated and remain entrapped within the polymer.

[0026] Denaturant The polymerization reaction may be carried out in the presence of a modifier, sometimes referred to as a polar coordinator or vinyl modifier. As those skilled in the art will appreciate, these compounds can serve multiple purposes in the polymerization. For example, they can help randomize the comonomers throughout the polymer chain. They can also modify the vinyl content of diene-derived monomer units. Compounds useful as modifiers include those containing oxygen or nitrogen heteroatoms and non-bonding electron pairs. Examples include linear and cyclic oligomeric oxolanyl alkanes; dialkyl ethers of mono- and oligoalkylene glycols (also known as glyme ethers); "crown" ethers; tertiary amines; linear THF oligomers; and the like. Linear and cyclic oligomeric oxolanyl alkanes are described in U.S. Pat. Nos. 4,429,091 and 9,868,795, which are incorporated herein by reference. Specific examples of compounds useful as randomizers include 2,2-bis(2-oxolanyl)propane (also known as 2,2-ditetrahydrofurylpropane), meso-2,2-ditelahydrofurylpropane, DL-2,2-ditelahydrofurylpropane, and mixtures thereof, 1,2-dimethoxyethane, N,N,N',N'-tetramethylethylenediamine (TMEDA), tetrahydrofuran (THF), 1,2-dipiperidylethane, dipiperidylmethane, hexamethylphosphoramide, N,N'-dimethylpiperazine, diazabicyclooctane, dimethyl ether, diethyl ether, tri-n-butylamine, and mixtures thereof. In other embodiments, potassium alkoxides may be used to randomize the styrene distribution. In one or more embodiments, randomizers other than potassium alkoxides are used. In other embodiments, potassium alkoxides are the only randomizers present in the polymerization mixture.

[0027] The amount of randomizer to be used may depend on various factors, such as the desired polymer microstructure, the ratio of monomer to comonomer, the polymerization temperature, and the nature of the particular randomizer used.

[0028] Polymerization conditions and techniques The incorporation of the anionic initiator and randomizer into the polymerization system can be accomplished by a variety of methods. In one or more embodiments, the anionic initiator and randomizer may be added separately to the monomers to be polymerized, either stepwise or simultaneously.

[0029] As described above, reactive polymers are produced by polymerizing a conjugated diene monomer together with a monomer copolymerizable with the conjugated diene monomer in the presence of an effective amount of an initiator. The introduction of the initiator, conjugated diene monomer, comonomer, and solvent forms a polymerization mixture in which the reactive polymer is formed. Polymerization in a solvent produces a polymerization mixture in which the polymer product is dissolved or suspended in the solvent. This polymerization mixture is sometimes referred to as a polymer cement.

[0030] In one or more embodiments, the polymerization may be carried out in any conventional polymerization vessel known in the art. For example, the polymerization may be carried out in a conventional stirred tank reactor. In one or more embodiments, all of the ingredients used for the polymerization may be mixed in a single vessel (e.g., a conventional stirred tank reactor), and all steps of the polymerization process may be carried out in this vessel. In other embodiments, two or more ingredients may be precombined in one vessel and then transferred to another vessel where polymerization of the monomers (or at least the majority of it) occurs. Because various embodiments of the present invention involve the use of multiple reactors or reaction zones, the vessel in which the polymerization occurs (e.g., a tank reactor) may be referred to as the first vessel or first reaction zone.

[0031] The polymerization can be carried out as a batch, continuous, or semi-continuous process. In a semi-continuous process, monomer is intermittently introduced as needed to replace already polymerized monomer. In one or more embodiments, the heat of polymerization can be removed by external cooling through a thermally controlled reactor jacket, internal cooling by vaporizing and condensing the monomer using a reflux condenser connected to the reactor, or a combination of the two methods. Conditions can also be controlled to carry out the polymerization under pressures of about 0.1 atmospheres to about 50 atmospheres, in other embodiments, about 0.5 atmospheres to about 20 atmospheres, and in other embodiments, about 1 atmosphere to about 10 atmospheres. In one or more embodiments, pressures at which the polymerization can be carried out include those that ensure that the majority of the monomer is in the liquid phase. In these or other embodiments, the polymerization mixture can be maintained under anaerobic conditions.

[0032] In one or more embodiments, the conditions under which the polymerization proceeds may be controlled to maintain a peak polymerization temperature of the polymerization mixture above 30° C., in other embodiments above 50° C., and in other embodiments above 70° C. In these or other embodiments, the conditions under which the polymerization proceeds may be controlled to maintain a peak polymerization temperature of the polymerization mixture below 120° C., in other embodiments below 110° C., and in other embodiments below 100° C. In one or more embodiments, the conditions under which the polymerization proceeds may be controlled to maintain the temperature of the polymerization mixture in the range of from about −10° C. to about 200° C., in other embodiments from about 0° C. to about 150° C., and in other embodiments from about 20° C. to about 110° C.

[0033] Polymer Functionalization As noted above, because branched polymers are prepared by anionic polymerization techniques, the branches are reactive and can be modified (sometimes referred to as functionalized) to provide multifunctional branched polymers. That is, the reactive ends of the polymer are modified by introducing a functionalizing agent into the polymerization mixture, sometimes referred to as functionalization. It is believed that the polymer chain ends react with the functionalizing agent (sometimes referred to as a modifying agent) to provide residues of the functionalizing agent at the ends of the polymer chains. Thus, the reaction between a branched polymer and a functionalizing agent produces a branched polymer composition in which two or more of the polymer branches of any branched polymer molecule contain end groups derived from the functionalizing agent. It should be understood that the reaction between a functionalizing agent and a reactive polymer branch can also result in the polymer coupling of two or more branched polymers. In either case, both branched polymers having chain end functional groups and branched polymers coupled with residues of a functionalizing agent are referred to as modified polymers or functionalized branched polymers, unless otherwise specified.

[0034] Functionalizing Agents Useful functionalizing agents include those conventionally used in the art. As will be understood by those skilled in the art, functionalizing agents impart terminal functionality that may be reactive or interactive with other polymer chains (propagating and / or non-propagating) or with other materials in the rubber compound, such as particulate reinforcing fillers (e.g., carbon black or silica). As discussed above, increased interaction between the polymer and the particulate filler in the rubber compound improves the mechanical and dynamic properties of the resulting vulcanizate. For example, certain functionalizing agents may impart terminal functional groups containing one or more heteroatoms. In one or more embodiments, functionalizing agents can produce functionalized polymers that can be used in rubber compositions that can provide vulcanizates that have lower high-temperature (e.g., 50°C) hysteresis loss than vulcanizates prepared from similar rubber compounds without the functionalized polymer. The reduction in high-temperature hysteresis loss can be at least 5%, in some cases at least 10%, and even at least 15%.

[0035] Exemplary types of compounds that can be used to end-functionalize the reactive branched polymers of the present invention include imines, amines, hydrocarbyloxysilanes, amine-containing hydrocarbyloxysilanes, halogenated organics, trialkyltin compounds, carbon dioxide, benzophenones, benzaldehydes, imidazolidinones, pyrrolidinones, carbodiimides, ureas, isocyanates, and Schiff bases. It should also be understood that two or more different types of functionalizing agents can be used in the practice of the present invention.

[0036] Hydrocarbyloxysilane Functionalizing Agents In one or more embodiments, the hydrocarbyloxysilane functionalizing agent may be defined by the following formula: (R 1 ) 4-z-y Si(R 2 )y(OR 2 ) z In the formula, R 1 is a halogen atom or a monovalent organic group, and each R 2 is a monovalent organic group, z is an integer from 1 to 4, and y is an integer from 0 to 2. In one embodiment, the halogen atom is chlorine.

[0037] In one or more embodiments, monovalent organic groups include hydrocarbyl groups such as, but not limited to, alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, aryl, aralkyl, alkaryl, or alkynyl groups. Hydrocarbyl groups also include substituted hydrocarbyl groups, which refer to hydrocarbyl groups in which one or more hydrogen atoms have been replaced by a substituent (e.g., a hydrocarbyl group). In one or more embodiments, these groups may contain from 1 (or the minimum number of carbon atoms appropriate to form the group) to about 20 carbon atoms. These groups may or may not contain heteroatoms. Suitable heteroatoms include, but are not limited to, nitrogen, boron, oxygen, silicon, sulfur, tin, and phosphorus atoms. In one or more embodiments, the cycloalkyl, cycloalkenyl, and aryl groups are non-heterocyclic groups. In these or other embodiments, the substituents forming the substituted hydrocarbyl groups are non-heterocyclic groups.

[0038] Suitable examples of siloxane endstoppers include tetraalkoxysilanes, alkylalkoxysilanes, arylalkoxysilanes, alkenylalkoxysilanes, and haloalkoxysilanes.

[0039] Examples of tetraalkoxysilane compounds include tetramethyl orthosilicate, tetraethyl orthosilicate, tetrapropyl orthosilicate, tetrabutyl orthosilicate, tetra(2-ethylhexyl) orthosilicate, tetraphenyl orthosilicate, and tetratoluyloxysilane.

[0040] Examples of alkylalkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-propoxysilane, methyltri-n-butoxysilane, methyltriphenoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltri-n-propoxysilane, ethyltri-n-butoxysilane, ethyltriphenoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-n-propoxysilane, dimethyldi-n-butoxysilane, dimethyldiphenoxysilane, diethyldimethoxysilane, and diphenyldimethoxysilane.

[0041] Examples of arylalkoxysilane compounds include phenyltrimethoxysilane, phenyltriethoxysilane, phenyltri-n-propoxysilane, phenyltri-n-butoxysilane, and phenyltriphenoxysilane.

[0042] Examples of alkenylalkoxysilane compounds include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-propoxysilane, vinyltri-n-butoxysilane, vinyltriphenoxysilane, allyltrimethoxysilane, octenyltrimethoxysilane, and divinyldimethoxysilane.

[0043] Examples of haloalkoxysilane compounds include trimethoxychlorosilane, triethoxychlorosilane, tri-n-propoxychlorosilane, tri-n-butoxychlorosilane, triphenoxychlorosilane, dimethoxydichlorosilane, diethoxydichlorosilane, di-n-propoxydichlorosilane, diphenoxydichlorosilane, methoxytrichlorosilane, ethoxytrichlorosilane, n-propoxytrichlorosilane, phenoxytrichlorosilane, trimethoxybromosilane, triethoxybromosilane, tri-n-propoxybromosilane, triphenoxybromosilane, dimethoxydibromosilane, Examples of the iodosilane include mosilane, diethoxydibromosilane, di-n-propoxydibromosilane, diphenoxydibromosilane, methoxytribromosilane, ethoxytribromosilane, n-propoxytribromosilane, phenoxytribromosilane, trimethoxyiodosilane, triethoxyiodosilane, tri-n-propoxyiodosilane, triphenoxyiodosilane, dimethoxydiiodosilane, di-n-propoxydiiodosilane, diphenoxydiiodosilane, methoxytriiodosilane, ethoxytriiodosilane, n-propoxytriiodosilane, and phenoxytriiodosilane.

[0044] Techniques for preparing functionalized polymers by using hydrocarbyloxysilane compounds are described in U.S. Pat. Nos. 3,244,664, 6,008,295, 6,228,908, and 4,185,042, which are incorporated herein by reference.

[0045] In one or more embodiments, the hydrocarbyloxysilane functionalizing agent is an imino-containing hydrocarbyloxysilane that can be defined by the following formula:

[0046] [ka] In the formula, R 2 , R 3 and R 7 is a monovalent organic group, and R 4 is a divalent organic group, and R 5and R 6 are each independently a hydrocarbyloxy group or a hydrocarbyl group.

[0047] In one or more embodiments, the divalent organic group is a hydrocarbylene group, such as, but not limited to, an alkylene, cycloalkylene, alkenylene, cycloalkenylene, alkynylene, cycloalkenylene, or arylene group. Hydrocarbylene groups include substituted hydrocarbylene groups, which refer to hydrocarbylene groups in which one or more hydrogen atoms have been replaced with a substituent (e.g., a hydrocarbyl group). In one or more embodiments, these groups may contain from 1 (or the minimum number of carbon atoms appropriate to form the group) to about 20 carbon atoms. These groups may or may not contain heteroatoms. Suitable heteroatoms include, but are not limited to, nitrogen, boron, oxygen, silicon, sulfur, tin, and phosphorus atoms. In one or more embodiments, the cycloalkylene, cycloalkenylene, and arylene groups are non-heterocyclic groups. In these or other embodiments, the substituents forming the substituted hydrocarbylene group are non-heterocyclic groups.

[0048] Examples of these imino-containing hydrocarbyloxysilane compounds include, but are not limited to, triethoxy compounds such as N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(triethoxysilyl)-1-propanamine. Other examples include, but are not limited to, trimethoxy compounds such as N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(trimethoxysilyl)-1-propanamine, N-ethylidene-3-(trimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(trimethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(trimethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(trimethoxysilyl)-1-propanamine. Other examples include, but are not limited to, methyldiethoxy compounds such as N-(1,3-dimethylbutylidene)-3-(methyldiethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(methyldiethoxysilyl)-1-propanamine, N-ethylidene-3-(methyldiethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(methyldiethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(methyldiethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(methyldiethoxysilyl)-1-propanamine.Other examples include, but are not limited to, ethyldimethoxy compounds such as N-(1,3-dimethylbutylidene)-3-(ethyldimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(ethyldimethoxysilyl)-1-propanamine, N-ethylidene-3-(ethyldimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(ethyldimethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(ethyldimethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(ethyldimethoxysilyl)-1-propanamine.

[0049] Techniques for preparing functionalized polymers by using imine-containing hydrocarbyloxy compounds are disclosed in U.S. Patent Application Publication Nos. 2005 / 0009979, 2010 / 0113683, and 2011 / 0092633, which are incorporated herein by reference.

[0050] In one or more embodiments, the hydrocarbyloxysilane functionalizing agent is a hydrocarbyloxysilane defined by the formula:

[0051] [ka] In the formula, R 4 is a divalent organic group, and R 5 and R 6 are each independently a hydrocarbyloxy group or a hydrocarbyl group, and R 5 is a monovalent organic group, and A is selected from the group consisting of carboxylic acid esters, cyclic tertiary amines, acyclic tertiary amines, pyridines, silazanes, and sulfide groups.

[0052] Examples of hydrocarbyloxysilane compounds containing carboxylic acid ester groups include, but are not limited to, 3-methacryloyloxypropyltriethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, and 3-methacryloyloxypropyltriisopropoxysilane.

[0053] Examples of hydrocarbyloxysilane compounds containing a cyclic tertiary amine group include 3-(1-hexamethyleneimino)propyltriethoxysilane, 3-(1-hexamethyleneimino)propyltrimethoxysilane, (1-hexamethyleneimino)methyltriethoxysilane, (1-hexamethyleneimino)methyltrimethoxysilane, 2-(1-hexamethyleneimino)ethyltriethoxysilane, 3-(1-hexamethyleneimino)ethyltrimethoxysilane, and 2-(1-hexamethyleneimino)ethyltriethoxysilane. propyltriethoxysilane, 3-(1-pyrrolidinyl)propyltrimethoxysilane, 3-(1-pyrrolidinyl)propyltriethoxysilane, 3-(1-heptamethyleneimino)propyltriethoxysilane, 3-(1-dodecamethyleneimino)propyltriethoxysilane, 3-(1-hexamethyleneimino)propyldiethoxymethylsilane, and 3-[10-(triethoxysilyl)decyl]-4-oxazoline.

[0054] Examples of hydrocarbyloxysilane compounds containing acyclic tertiary amine groups include 3-dimethylaminopropyltriethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 3-diethylaminopropyltriethoxysilane, 2-dimethylaminoethyltriethoxysilane, 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyldiethoxymethylsilane, 3-diethylaminopropyldiethoxymethylsilane, These include, but are not limited to, 3-dimethylaminopropyldimethoxymethylsilane, 3-dimethylaminopropyldimethoxymethylsilane, and 3-dibutylaminopropyltriethoxysilane.

[0055] Examples of hydrocarbyloxysilane compounds containing pyridine groups include, but are not limited to, 2-trimethoxysilylethylpyridine.

[0056] Examples of hydrocarbyloxysilane compounds containing silazane groups include, but are not limited to, N,N-bis(trimethylsilyl)-aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldimethoxysilane, and N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane.

[0057] Further examples of useful functionalizing agents include trialkyltin halides such as triisobutyltin chloride, as disclosed in U.S. Patent Nos. 4,519,431, 4,540,744, 4,603,722, 5,248,722, 5,349,024, 5,502,129, and 5,877,336. Useful halogenated organic compounds include cyclic amino compounds such as hexamethyleneimine alkyl chlorides, as disclosed in U.S. Patent Nos. 5,786,441, 5,916,976, and 5,552,473. Further examples include cyclic sulfur- or oxygen-containing azaheterocycles as disclosed in International Patent Publication No. 2004 / 020475, U.S. Patent Application Publication No. 2006 / 0178467, and U.S. Patent No. 6,596,798. Other examples include boron-containing terminators as disclosed in U.S. Patent No. 7,598,322, which is incorporated herein by reference. Still other examples include cyclic siloxanes such as hexamethylcyclotrisiloxane, including those disclosed in U.S. Patent No. 9,920,149, which is incorporated herein by reference. Still other examples include polydimethylsiloxanes.

[0058] Amount of functionalizing agent used The amount of functionalizing agent used in the practice of the present invention can be described in terms of the lithium or metal cation associated with the initiator. In one or more embodiments, the amount of functionalizing agent introduced into the polymerization mixture is greater than 0.70, in other embodiments greater than 0.75, in other embodiments greater than 0.80, in other embodiments greater than 0.85, and in other embodiments greater than 0.90 moles of functionalizing agent per mole of lithium in the initiator. In these or other embodiments, less than 0.99 moles, in other embodiments less than 0.97 moles, and in other embodiments less than 0.95 moles of functionalizing agent per mole of lithium are introduced into the polymerization mixture. In one or more embodiments, from about 0.7 to about 1.0 moles, in other embodiments from about 0.75 to about 0.99 moles, and in other embodiments from about 0.80 to about 0.97 moles of functionalizing agent per mole of lithium are introduced into the polymerization mixture.

[0059] Functionalization Reactions The reaction of each type of functionalizing agent with the polymer can be carried out by introducing the functionalizing agents to the reactive polymer sequentially or simultaneously.

[0060] In one or more embodiments, the reaction between the functionalizing agent and the reactive polymer may occur at a temperature of from about 10° C. to about 150° C., and in other embodiments, from about 20° C. to about 100° C. The time required for the reaction between the functionalizing agent and the reactive polymer to be complete depends on various factors, including the type and amount of initiator used in preparing the reactive polymer, the type and amount of functionalizing agent, and the temperature at which the functionalization reaction is carried out. In one or more embodiments, the reaction between the functionalizing agent and the reactive polymer may be carried out for about 10 to 60 minutes.

[0061] In one or more embodiments, the functionalizing agent is introduced into the polymer cement (i.e., polymerization mixture) while the polymer is dissolved or suspended in the solvent. As will be understood by those skilled in the art, this solution may be referred to as a polymer cement, or more specifically, a reactive or living polymer cement. In one or more embodiments, the characteristics of the polymer cement, such as its concentration, are the same as or similar to the characteristics of the cement prior to functionalization. The composition comprising the functionalized polymer and solvent may be referred to as a polymerization mixture, or in other words, a polymerization mixture comprising a functionalized polymer.

[0062] In one or more embodiments, the polymer modification (i.e., the introduction of the functionalizing agent into the polymer cement) occurs in the same vessel in which the polymerization occurs. In other embodiments, the polymer modification occurs outside of the reaction vessel in which the polymerization occurs. For example, the first and second functionalizing agents can be introduced into the polymerization mixture (i.e., the polymer cement) in a downstream vessel or downstream transfer conduit.

[0063] According to one or more embodiments, as a result of the functionalization reaction, greater than 60 mol %, in other embodiments greater than 70 mol %, in other embodiments greater than 80 mol %, in other embodiments greater than 85 mol %, in other embodiments greater than 90 mol %, and in other embodiments greater than 95 mol % of the polymer chains or branches (i.e., reactive chains of the branched polymer) in the polymer cement comprise a terminal functional group (i.e., residues of a functionalizing agent). In one or more embodiments, from about 60 mol % to about 100 mol %, in other embodiments from about 70 mol % to about 99 mol %, in other embodiments from about 80 mol % to about 98 mol %, and in other embodiments from about 90 mol % to about 97 mol % of the polymer chains or branches in the polymer composition comprise a terminal functional group.

[0064] Post-polymerization and functionalization Polymer Stabilization In one or more embodiments, after modification, the modified polymer (i.e., the multifunctionalized branched polymer) can be optionally stabilized. That is, the modified polymer can be stabilized by introducing a stabilizer into the polymerization mixture containing the modified polymer. It is believed that the stabilizer reacts with certain terminal functional groups (e.g., hydrocarbyloxy substituents), and this reaction can occur either upon introduction of the two molecules or after aging of the composition.

[0065] In one or more embodiments, stabilizers known in the art may be used. For example, the stabilizer may include an alkylalkoxysilane as disclosed in U.S. Pat. No. 6,255,404, which is incorporated herein by reference. An exemplary alkylalkoxysilane is octyltriethoxysilane. In other embodiments, the stabilizer may include a long-chain alcohol as disclosed in U.S. Pat. No. 6,279,632, which is incorporated herein by reference. An exemplary long-chain alcohol is sorbitan stearate or sorbitan monooleate. In still other embodiments, the polymer may be stabilized by treating it with an alkylalkoxysilane, as disclosed in U.S. Pat. No. 9,546,237, which is incorporated herein by reference, followed by treatment with a silane containing a hydrolyzable group that forms an acidic species upon hydrolysis, such as methyltrichlorosilane.

[0066] In one or more embodiments of the present invention, arylsilanols (also known as hydroxyphenylsilanes) are advantageously used as stabilizers. Useful arylsilanols are disclosed in U.S. Patent No. 9,255,167, which is incorporated herein by reference. Exemplary arylsilanols include, but are not limited to, triphenylsilanol, also known as hydroxytriphenylsilane, diphenylsilanediol, also known as dihydroxydiphenylsilane, and phenylsilanetriol, also known as trihydroxy(phenyl)silane.

[0067] In one or more embodiments, the functionalized polymers of the present invention can be stabilized by treatment with a silane containing a hydrolyzable group that forms an acidic species upon hydrolysis, either simultaneously with or after treatment with an aryl silanol (e.g., an aryl silane diol or aryl silane triol). Silanes containing a hydrolyzable group that forms an acidic species upon hydrolysis are disclosed in U.S. Patent No. 9,546,237, which is incorporated herein by reference. In certain embodiments, the functionalized polymer is treated with diphenyl silane diol and trimethylsilyl chloride.

[0068] In one or more embodiments, the stabilizing agent is added to the polymer cement after sufficient time has been provided to complete the reaction between the reactive polymer and the functionalizing agent. In one or more embodiments, the stabilizing agent is added to the polymer cement 30 minutes, in other embodiments 15 minutes, and in other embodiments 10 minutes after the time the functionalizing agent is introduced to the polymer cement.

[0069] The amount of stabilizer (e.g., arylsilanol) used in the practice of the present invention can be described in terms of the number of moles of lithium relative to the initiator. In one or more embodiments, greater than 0.5 moles, in other embodiments greater than 1 mole, in other embodiments greater than 2 moles, and in other embodiments greater than 3 moles of stabilizer are introduced into the polymerization mixture per mole of lithium in the initiator. In these or other embodiments, less than 8 moles, in other embodiments less than 7 moles, in other embodiments less than 6 moles, in other embodiments less than 5 moles, and in other embodiments less than 4.5 moles of stabilizer are introduced into the polymerization mixture per mole of lithium. In one or more embodiments, from about 1 to about 7 moles, in other embodiments from about 2 to about 6 moles, and in other embodiments from about 3 to about 5 moles of stabilizer are introduced into the polymerization mixture per mole of lithium.

[0070] In other embodiments, the amount of stabilizer (e.g., aryl silanol) used in the practice of the present invention can be described as a molar ratio to the moles of functionalizing agent used. In one or more embodiments, the ratio of moles of stabilizer to moles of functionalizing agent used is from about 0.5:1 to about 8:1, from about 1:1 to about 7:1 in other embodiments, from about 2:1 to about 6:1 in other embodiments, and from about 3:1 to about 5:1 in other embodiments. In these or other embodiments, the ratio of moles of stabilizer to moles of functionalizing agent used is less than 7:1, less than 6:1 in other embodiments, less than 5.5:1 in other embodiments, less than 5:1 in other embodiments, and less than 4.5:1 in other embodiments.

[0071] When two reagents are used, for example, when treating a polymer with an aryl silanol (e.g., an aryl silanediol or aryl silanetriol) along with a silane containing hydrolyzable groups that form acidic species upon hydrolysis (e.g., a hydrocarbylsilyl chloride, such as trimethylsilyl chloride), the amounts of each reagent used can be the same or different. In one or more embodiments, the total amount of stabilizer (i.e., both compounds), when expressed as a molar ratio to the moles of functionalizing agent, is from about 3:1 to about 10:1, in other embodiments from about 4:1 to about 8:1, and in other embodiments from about 5:1 to about 7:1. In these or other embodiments, the molar ratio of aryl silanol to silane containing hydrolyzable groups that form acidic species upon hydrolysis is from about 0.5:1 to about 4:1, in other embodiments from about 1:1 to about 3:1, and in other embodiments from about 1.5:1 to about 2.5:1.

[0072] In one or more embodiments, stabilization of the polymer (i.e., introduction of the stabilizer) occurs in the same vessel in which polymerization occurred. In these embodiments, this includes the same vessel in which modification occurred. In other embodiments, stabilization of the polymer (i.e., introduction of the stabilizer) occurs outside the vessel in which polymerization occurred. Similarly, in one or more embodiments, stabilization of the polymer occurs outside the vessel in which polymer modification occurred. For example, in one or more embodiments, the stabilizer may be added to the polymerization mixture (i.e., polymer cement) in a vessel or transfer line downstream from the vessel in which polymerization occurred and downstream from the vessel in which polymer modification occurred. For purposes of this specification, the vessel or conduit into which the stabilizer is introduced relative to the polymerization vessel may also be referred to as a second vessel or second reaction zone. In other embodiments, the stabilizer may be introduced to the polymer while it is suspended or dissolved in the monomer.

[0073] Condensation accelerator In one or more embodiments, a condensation promoter may be added to the polymerization mixture after the functionalizing agent has been introduced into the reactive polymer, optionally after the addition of a quenching agent and / or antioxidant, optionally after or together with the stabilizer, and optionally after recovery or isolation of the functionalized polymer. Useful condensation promoters include tin and / or titanium carboxylates and tin and / or titanium alkoxides. One specific example is titanium 2-ethylhexyl oxide. Useful condensation catalysts and their uses are disclosed in U.S. Patent Application Publication No. 2005 / 0159554 (U.S. Patent No. 7,683,151), which is incorporated herein by reference. In other embodiments, organic acids can be used as condensation promoters. Useful types of organic acids include aliphatic, alicyclic, and aromatic monocarboxylic, dicarboxylic, tricarboxylic, and tetracarboxylic acids. Specific examples of useful organic acids include, but are not limited to, acetic acid, propionic acid, butyric acid, hexanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, cyclohexanoic acid, and benzoic acid.

[0074] The amount of condensation promoter used in the practice of the present invention can be described in terms of moles of lithium relative to the initiator. In one or more embodiments, the amount of condensation promoter per mole of lithium is greater than 1.0, in other embodiments greater than 1.5, and in other embodiments greater than 1.8 moles of condensation promoter per mole of lithium in the initiator. In these or other embodiments, less than 4.0, in other embodiments less than 3.3, and in other embodiments less than 3.0 moles of condensation promoter per mole of lithium are introduced into the polymerization mixture. In one or more embodiments, from about 1.0 to about 4.0, in other embodiments from about 1.5 to about 3.3, and in other embodiments from about 1.8 to about 3.0 moles of condensation promoter per mole of lithium are introduced into the polymerization mixture.

[0075] antioxidants In one or more embodiments, an antioxidant may be added to the polymerization mixture after the functionalizing agent has been introduced into the reactive polymer, optionally after the addition of a quenching agent and / or antioxidant, optionally after or together with the stabilizer, and optionally after recovery or isolation of the functionalized polymer. An exemplary antioxidant includes 2,6-di-tert-butyl-4-methylphenol.

[0076] In one or more embodiments, processing aids and other optional additives, such as oils, may be added to the polymer cement after the polymer is formed.

[0077] Optional Quenching In one or more embodiments, after the polymerization reaction or after the reaction between the reactive polymer and the functionalizing agent is achieved or completed, a quenching agent can be added to the polymerization mixture to deactivate any remaining reactive polymer chains and catalyst or catalyst components. Quenching agents can include protic compounds, including, but not limited to, alcohols, carboxylic acids, inorganic acids, water, or mixtures thereof. The amount of quenching agent used can range from 0.5 to 10 moles of quenching agent per mole of lithium used to initiate the polymerization.

[0078] Desolvation of polymers After polymerization and / or polymer modification, optional stabilization, optional introduction of a condensation promoter and / or introduction of an antioxidant, the polymer product can be separated from the solvent, which is sometimes referred to as desolventization. In other words, as described above, the polymer is synthesized in an organic solvent, and during the desolventization step, the organic solvent is separated from the resulting polymer.

[0079] In certain embodiments, desolventization involves hot water and / or steam coagulation. For example, a polymerization mixture containing a blend of modified polymers can be combined with steam or a hot water stream. The heat associated with the steam or hot water stream volatilizes the solvent and any unreacted monomers. The polymer product is then dispersed within the aqueous phase, for example, in the form of polymer crumbs. The nature and size of the polymer crumbs can generally be manipulated by the introduction of mechanical energy (e.g., in the form of a mixer).

[0080] In one or more embodiments, the polymer crumbs are temporarily stored in water as a crumb dispersion until the subsequent drying step described below. The crumb dispersion is generally a mixture of polymer particles or crumbs and water. The polymer particles, sometimes referred to as coagulated polymer, are generally macroscale and have dimensions of at least 1 mm or greater. This crumb dispersion can be contained in a vessel, such as a conventional reactor vessel, such as a continuous stirred tank reactor.

[0081] In one or more embodiments, the polymer crumbs may be further processed to remove residual solvent and dry the polymer (i.e., separate the polymer from the water). In the practice of the present invention, the polymer may be dried using conventional techniques, which may include one or more of filtration, squeezing, and heating. After desolventization and drying, the volatile content of the dried polymer may be less than 2.0% by weight of the polymer, less than 1.0% by weight in other embodiments, and less than 0.5% by weight in other embodiments.

[0082] In other embodiments, the polymer product may be stripped using a devolatilizer, which is an extruder-type device that may operate in conjunction with heat and / or vacuum. In yet other embodiments, the polymerization mixture may be directly drum dried.

[0083] Regardless of the method used to desolventize and dry the polymer, the finished polymer product may be referred to as a dried polymer. The dried polymer may be shaped or otherwise manipulated into bales using conventional techniques.

[0084] Characteristics of branched polymers Branched polymers can be characterized by their molecular weight, in particular their weight average molecular weight (Mw). As those skilled in the art will appreciate, the weight average molecular weight of a branched polymer can be determined by using gel permeation chromatography (GPC) equipped with a multi-angle light scattering (MALLS) detector.

[0085] In one or more embodiments, the unfunctionalized branched polymer has a Mw, sometimes referred to as the base Mw, greater than 250 kg / mol, in other embodiments greater than 350 kg / mol, and in other embodiments greater than 450 kg / mol. In these or other embodiments, the branched polymer has a Mw less than 850 kg / mol, in other embodiments less than 800 kg / mol, and in other embodiments less than 750 kg / mol. In one or more embodiments, the branched polymer has a Mw of from about 350 to about 850 kg / mol, in other embodiments from about 450 to about 800 kg / mol, and in other embodiments from about 550 to about 750 kg / mol.

[0086] In one or more embodiments, the functionalized branched polymer has a Mw greater than 350 kg / mol, greater than 450 kg / mol in other embodiments, and greater than 550 kg / mol in other embodiments. In these or other embodiments, the branched polymer has a Mw less than 1300 kg / mol, less than 1200 kg / mol in other embodiments, and less than 1100 kg / mol in other embodiments. In one or more embodiments, the branched polymer has a Mw of from about 350 to about 1300 kg / mol, from about 450 to about 1200 kg / mol in other embodiments, and from about 550 to about 1200 kg / mol in other embodiments.

[0087] Branched polymers produced according to aspects of the present invention can be characterized by their vinyl content, which can be described as the number of unsaturations in the 1,2-microstructure relative to the total unsaturation in the polymer chain. As will be appreciated by those skilled in the art, vinyl content can be determined by NMR analysis at 400 MHz using CDCl3 as the solvent. In one or more embodiments, the branched polymer contains greater than 10% by weight, greater than 20% by weight in other embodiments, and greater than 35% by weight in other embodiments. In these or other embodiments, the branched polymer contains less than 80% by weight, less than 60% by weight in other embodiments, and less than 46% by weight in other embodiments. In one or more embodiments, the branched polymer contains from about 10 to about 80% by weight, from about 20 to about 60% by weight in other embodiments, and from about 35 to about 46% by weight in other embodiments.

[0088] Branched polymers produced according to aspects of the present invention can be characterized by their bound styrene content (i.e., the amount of styrene incorporated into the polymer chain), which refers to the weight percent of vinyl aromatic monomer incorporated into the polydiene copolymer. As will be understood by those skilled in the art, bound styrene can be determined by reference to the relative weight of vinyl monomer contained in the polymerization mixture to the diene monomer. Alternatively, bound styrene can be determined by NMR analysis at 400 MHz using CDCl3 as the solvent. In one or more embodiments, the branched polymer contains greater than 20 wt%, greater than 25 wt% in other embodiments, and greater than 30 wt% in other embodiments. In these or other embodiments, the reactive copolymer contains less than 60 wt%, less than 55 wt%, and less than 50 wt% in other embodiments. In one or more embodiments, the reactive copolymer contains from about 20 wt% to about 60 wt%, from about 25 wt% to about 55 wt%, and in other embodiments, from about 30 wt% to about 50 wt% bound styrene.

[0089] The unfunctionalized branched polymers produced according to embodiments of the present invention can be characterized by T80, which is determined according to ASTM D 1646-19A using a Mooney viscometer (e.g., manufactured by Agilent Technologies) with a large rotor at 100°C and a 4 minute run time after a 1 minute preheat (i.e., ML 1+4 @100°C). In one or more embodiments, the unfunctionalized branched polymer has a T80 of greater than 2 minutes, in other embodiments greater than 4 minutes, in other embodiments greater than 6 minutes, and in other embodiments greater than 8 minutes. In one or more embodiments, the unfunctionalized branched polymer has a T80 of from about 2 to about 15 minutes, in other embodiments from about 4 to about 14 minutes, and in other embodiments from about 6 to about 12 minutes.

[0090] Branched polymers produced according to aspects of the present invention can be characterized by their Mooney viscosity, which is determined using a Monsanto Mooney Viscometer with a large rotor at 100°C with a 1 minute preheat and a 4 minute run time (i.e., ML1+4@100°C). In one or more embodiments, the branched polymers have a Mooney viscosity greater than 20, greater than 30 in other embodiments, and greater than 40 in other embodiments. In these or other embodiments, the branched polymers have a Mooney viscosity less than 80, less than 70 in other embodiments, and less than 60 in other embodiments. In one or more embodiments, the branched polymers have a Mooney viscosity of from about 20 to about 80, from about 30 to about 70 in other embodiments, and from about 40 to about 60 in other embodiments.

[0091] Branched polymers produced according to aspects of the present invention can be characterized by a Tg determined according to ASTM E1356-08 using differential scanning calorimetry (DSC) techniques. In one or more embodiments, it is less than -20°C, in other embodiments less than -30°C, and in other embodiments less than -40°C. In one or more embodiments, the branched polymer has a Tg of about -65 to about -30°C, in other embodiments about -60 to about -30°C, and in other embodiments about -50 to about -40°C. INDUSTRIAL APPLICABILITY

[0092] In one or more embodiments, the branched polymers of the present invention can be used in compounding vulcanizable rubber compositions that can be useful, for example, in preparing tire components. Rubber compounding techniques and additives used therein are generally disclosed in "The Compounding and Vulcanization of Rubber," in Rubber Technology (2nd Ed. 1973).

[0093] Generally speaking, these vulcanizable rubber compositions include a vulcanizable rubber component, a reinforcing filler, and a curative or curative system. These compositions may also optionally include metal activators, resins, and processing oils, as well as various ingredients that may conventionally be included in these vulcanizable rubber compositions.

[0094] In one or more embodiments, the branched polymers of the present invention may form all or part of the rubber component of the vulcanizable composition, i.e., the rubber component may include other vulcanizable rubbers, sometimes referred to as elastomeric polymers or simply elastomers.

[0095] Rubber compositions can be prepared by using the branched polymers of the present invention alone or with other elastomers (i.e., polymers that can be vulcanized to form compositions with rubbery or elastomeric properties). Other elastomers that may be used include natural and synthetic rubbers. Synthetic rubbers are typically obtained from the polymerization of conjugated diene monomers, copolymerization of conjugated diene monomers with other monomers such as vinyl-substituted aromatic monomers, or copolymerization of ethylene with one or more α-olefins and, optionally, one or more diene monomers.

[0096] Exemplary synthetic rubbers include synthetic polyisoprene, polybutadiene, polyisobutylene-co-isoprene, neoprene, poly(ethylene-co-propylene), poly(styrene-co-butadiene), poly(styrene-co-isoprene), poly(styrene-co-isoprene-co-butadiene), poly(isoprene-co-butadiene), poly(ethylene-co-propylene-co-diene), polysulfide rubber, acrylic rubber, urethane rubber, silicone rubber, epichlorohydrin rubber, and mixtures thereof. These elastomers can have a myriad of macromolecular structures, including linear, branched, and star structures. Natural rubber is synthesized by and obtained from plant life. For example, natural rubber can be obtained from Hevea rubber trees, guayule shrub, gopher plant, mariola, rabbitbrush, milkweed, goldenrods, pale Indian plantain, rubber vine, Russian dandelions, mountain mint, American germander, and tall bellflower.

[0097] Generally, the rubber compositions of the present invention comprise from about 30% to about 65% by weight, and in other embodiments from about 35% to about 60% by weight, and in other embodiments from about 40% to about 55% by weight of rubber (i.e., rubber component), based on the total weight of the tire components.

[0098] In one or more embodiments, the rubber component of the rubber composition of the present invention comprises from about 1% to about 100% by weight, in other embodiments from about 10% to about 90% by weight, and in other embodiments from about 20% to about 80% by weight of the branched polymer produced by the technology of the present invention.

[0099] As mentioned above, the rubber composition may include fillers such as inorganic and organic fillers. Examples of organic fillers include carbon black and starch. Examples of inorganic fillers include silica, aluminum hydroxide, magnesium hydroxide, mica, talc (hydrated magnesium silicate), and clay (hydrated aluminum silicate). Carbon black and silica are the most common fillers used in tire manufacturing. In certain embodiments, a mixture of different fillers may be advantageously used.

[0100] The total filler amount used in the rubber composition may be up to about 150 parts by weight per 100 parts by weight of rubber (phr), with from about 5 to about 125 phr, or from about 30 to about 110 phr being typical. In certain embodiments, the total filler content is greater than about 100 phr. In other embodiments, the total filler content is from about 50 to about 100 phr, and in further embodiments, from about 55 to about 95 phr.

[0101] In one or more embodiments, carbon blacks include furnace blacks, channel blacks, and lamp blacks. More specific examples of carbon blacks include super abrasion furnace blacks, medium super abrasion furnace blacks, high abrasion furnace blacks, high speed extrusion furnace blacks, fine furnace blacks, semi-reinforced furnace blacks, medium processed channel blacks, hard processed channel blacks, conductive channel blacks, and acetylene blacks.

[0102] In certain embodiments, the carbon black has a surface area (EMSA) of at least 20 m 2 / g, in other embodiments, at least 35 m 2 The surface area may be expressed in terms of % by mass per gram, and the surface area value may be determined using the cetyltrimethylammonium bromide (CTAB) technique according to ASTM standard D-1765. The carbon black may be in pelletized or non-pelletized flocculent form. The preferred form of the carbon black may depend on the type of mixing equipment used to mix the rubber compound.

[0103] In one or more embodiments, the amount of carbon black used in the rubber composition may be up to about 75 parts by weight per 100 parts by weight of rubber (phr), with exemplary embodiments using from about 5 to about 6 parts by weight phr, or from about 10 to about 55 parts by weight phr.

[0104] In one or more embodiments, silica can be characterized by its surface area, which is a measure of its reinforcing properties. The Brunauer, Emmet, and Teller ("BET") method (described in J. Am. Chem. Soc., 1939, vol. 60, 2 pp. 309-319) is an accepted method for determining surface area. The BET surface area of ​​silica is generally 450 m 2 / g. A useful range of surface area is from about 32 to about 400 m2 / g, about 100~250m 2 / g, and about 150 to about 220 m 2 / g. In one or more embodiments, the silica may be characterized by a pH of from about 5 to about 7, or slightly above 7, or in other embodiments, from about 5.5 to about 6.8. In certain embodiments, the silica used in the rubber composition is derived exclusively from rice hull ash, and in other embodiments, the rubber composition is free of silica from a non-rice hull ash derived process.

[0105] Some commercially available silicas that can be used include Hi-Sil™ 215, Hi-Sil™ 233, and Hi-Sil™ 190 (PPG Industries, Inc.; Pittsburgh, Pa.) Other suppliers of commercially available silica include Grace Davison (Baltimore, Md.), Degussa Corp. (Parsippany, NJ), Rhodia Silica Systems (Cranbury, NJ), and JM Huber Corp. (Edison, NJ).

[0106] In one or more embodiments, the rubber composition may contain from about 1 to about 150 parts by weight of silica per 100 parts by weight of rubber, from about 5 to about 140 parts by weight in other embodiments, and from about 10 to about 130 parts by weight in other embodiments. In certain embodiments, the present invention includes rubber compositions having high silica loadings, for example, greater than 70 parts by weight per 100 parts by weight of rubber, greater than 90 parts by weight in other embodiments, and greater than 110 parts by weight in other embodiments, with the useful upper limit being limited by the high viscosity imparted by the silica. When silica is used in conjunction with carbon black, the amount of silica or carbon black can be as low as about 1 phr. In one or more embodiments, when carbon black and silica are used in combination as fillers, the weight ratio of silica to total filler may be from about 5% to about 99% by weight of total filler, from about 10% to about 90% by weight in other embodiments, or from about 50% to about 85% by weight in still other embodiments.

[0107] In one or more embodiments, when silica is used as a filler (alone or in combination with other fillers), a coupling agent may be added to the rubber composition during mixing to enhance the interaction of the silica with the elastomer. Useful coupling agents are disclosed in U.S. Patent Nos. 3,842,111, 3,873,489, 3,978,103, 3,997,581, 4,002,594, 5,580,919, 5,583,245, 5,663,396, 5,674,932, and 5,684. ,171, 5,684,172, 5,696,197, 6,608,145, 6,667,362, 6,579,949, 6,590,017, 6,525,118, 6,342,552, and 6,683,135, which are incorporated herein by reference.

[0108] In one or more embodiments, the amount of coupling agent may be from about 2% to about 30% by weight, from about 4% to about 25% by weight in other embodiments, and from about 6% to about 20% by weight in other embodiments, based on the weight of silica in the composition.

[0109] In one or more embodiments, when silica is used as a filler (alone or in combination with other fillers), a silica dispersant, which may include a silica shielding agent, may be included in the rubber compound. The use of one or more silica dispersants has been found to be particularly useful in the practice of the present invention in view of multifunctional polymers and / or high silica loadings. In one or more embodiments, useful silica dispersants include alkylalkoxysilanes, fatty acid esters of hydrogenated or non-hydrogenated C5 or C6 sugars, polyoxyethylene derivatives of fatty acid esters of hydrogenated or non-hydrogenated C5 or C6 sugars, and esters of polyols, including glycols and polyhydroxy compounds, and mixtures thereof. In a particular embodiment, the silica dispersant is glycol monostearate. Useful silane dispersants are disclosed in U.S. Pat. Nos. 6,608,145, 7,799,870, 7,897,661, 8,962,746, 9,758,639, 9,951,208, and U.S. Patent Application Publication Nos. 2004 / 0152811 and 2005 / 0070672, which are incorporated herein by reference.

[0110] In other embodiments, useful silica dispersants include metal glycerolates, such as zinc glycerolate, calcium glycerolate, and magnesium glycerolate, which are described in more detail in U.S. Pat. Nos. 10,087,306 and 11,220,595, and U.S. Patent Application Publication No. 2021 / 0388188, which are incorporated herein by reference.

[0111] In one or more embodiments, the rubber composition of the present invention may comprise from about 0.1% to about 30% by weight of silica dispersant, in other embodiments from about 1.0% to about 25% by weight of silica dispersant, in other embodiments from about 3.0% to about 20% by weight of silica dispersant, and in other embodiments from about 4.0% to about 10% by weight of silica dispersant, based on the weight of silica in the composition. In one or more embodiments, the rubber composition comprises greater than 3% by weight, in other embodiments greater than 5% by weight, and in other embodiments greater than 7% by weight of dispersant, based on the weight of silica. In these or other embodiments, the rubber composition may comprise greater than 3 parts by weight, in other embodiments greater than 4 parts by weight, in other embodiments greater than 5 parts by weight, and in other embodiments greater than 6 parts by weight of silica dispersant per 100 parts by weight of rubber.

[0112] A number of rubber curing agents (also called vulcanizing agents) may be used, including sulfur- or peroxide-based cure systems. Curing agents are described in Encyclopedia of Chemical Technology, Vol. 20, pp. 365-468, (3rd Ed. 1982), particularly "Vulcanization Agents and Auxiliary Materials," pp. 390-402, and A.Y. Coran, "Vulcanization," Encyclopedia of Polymer Science and Engineering, (2nd Ed. 1989), which are incorporated herein by reference. Vulcanizing agents may be used alone or in combination.

[0113] Other ingredients typically used in rubber compounding can also be added to the rubber composition. These include accelerators, accelerator activators, oils, plasticizers, waxes, antiscorch agents, processing aids, zinc oxide, tackifying resins, reinforcing resins, fatty acids such as stearic acid, peptizers, and antidegradants such as antioxidants and antiozonants. In certain embodiments, the oils used include those traditionally used as extender oils, as described above. Generally, the rubber compositions of the present invention can contain from about 1 to about 70 parts by weight, or in other embodiments from about 5 to about 50 parts by weight, of total oil per 100 parts by weight of rubber.

[0114] All components of the rubber composition can be mixed using standard mixing equipment, such as, but not limited to, Banbury mixers, Brabender mixers, intermesh mixers, including tandem intermesh mixers, extruders, kneaders, and two-roll mills. In one or more embodiments, the components are mixed in two or more stages. In the first stage (often referred to as the masterbatch mixing stage), a so-called masterbatch (typically containing the rubber component and filler) is prepared. To prevent premature vulcanization (also known as scorch), vulcanizing agents may be omitted from the masterbatch. The masterbatch may be mixed at an initiation temperature of about 25°C to about 125°C and an extrusion temperature of about 135°C to about 180°C. Once the masterbatch is prepared, vulcanizing agents may be introduced and mixed into the masterbatch in a final mixing stage, which is typically performed at a relatively low temperature to reduce the possibility of premature vulcanization. Optionally, an additional mixing stage, often referred to as a remill, may be used between the masterbatch mixing stage and the final mixing stage. When the rubber composition contains silica as a filler, one or more remill stages are often used, and the addition of various ingredients, including the polymer of the present invention, can occur during these remills.

[0115] Mixing procedures and conditions particularly applicable to silica-filled tire compounds are described in U.S. Patent Nos. 5,227,425, 5,719,207, and 5,717,022, and European Patent No. 890,606, all of which are incorporated herein by reference. In one embodiment, an initial masterbatch is prepared by including the polymer and silica in the substantial absence of coupling and shielding agents.

[0116] Rubber compositions prepared from the polymers of this invention are particularly useful in forming tire components such as treads, subtreads, sidewalls, body ply skims, bead fillers, etc. In one or more embodiments, these tread or sidewall compounds may include from about 10% to about 100% by weight, in other embodiments from about 35% to about 90% by weight, and in other embodiments from about 50% to about 80% by weight of the polymers of this invention (based on the total weight of rubber in the compound).

[0117] When rubber compositions are used in tire manufacturing, they can be processed into tire components using conventional tire manufacturing techniques, such as standard rubber molding, molding, and curing techniques. Typically, vulcanization is accomplished by heating the vulcanizable composition in a mold, which can be heated to, for example, about 140°C to about 180°C. The cured or crosslinked rubber composition may be referred to as a vulcanizate, which generally contains a thermoset three-dimensional polymer network. Other ingredients, such as fillers and processing aids, may be uniformly dispersed throughout the crosslinked network. Pneumatic tires can be made as described in U.S. Patent Nos. 5,866,171, 5,876,527, 5,931,211, and 5,971,046, which are incorporated herein by reference. [Example]

[0118] In order to demonstrate the practice of the present invention, the following examples have been prepared and tested. However, these examples should not be construed as limiting the scope of the invention. The claims shall define the invention.

[0119] Polymer samples 1-4 Sample 1: Synthesis of non-functional branched SBR A nitrogen-purged, jacketed steel reactor was charged with 2.76 pounds of anhydrous hexane, 2.33 mL of 1,3-diisopropenylbenzene (5.85 M, 1 equivalent to Li), 2.64 mL of 2,2-bis(2'-tetrahydrofuryl)propane (modifier) ​​(1.6 M in hexane, 0.31 equivalents to Li), and 9.72 mL of Sec-BuLi (1.4 M in cyclohexane, 2.00 mmol per 100 grams of monomer). The reaction mixture was stirred under an inert atmosphere at 80°F for 30 minutes. The reactor was charged with a mixture of 0.47 pounds of 32.2 wt% styrene in hexane and 6.55 pounds of 20.6 wt% butadiene in hexane, which had been premixed in a charge can. Immediately, 2.12 mL of potassium tert-amylate (KTA) (0.9 M in cyclohexane, 0.14 equivalents relative to Li) was added to the reactor, and the jacket temperature was set to 140°F. The solution temperature and reactor pressure were monitored by sensors located within the vessel. The batch temperature peaked at about 181°F after about 15 minutes. After an additional 40 minutes, the polymerization reaction was quenched by adding the polymer cement dropwise to a bucket containing about 8 L of isopropyl alcohol (IPA) and 15 g of 2,6-di-tert-butyl-4-methylphenol. The polymer was coagulated, drum-dried, and analyzed; the analytical results are reported in Table I.

[0120] Sample 2: Synthesis of non-functional branched SBR A batch of SBR cement was prepared as described for Sample 1, except that 3.18 mL of potassium tertiary amylate (KTA) (0.9 M in cyclohexane, 0.21 equivalents relative to Li) was added to the reactor immediately after dosing. The batch temperature peaked at about 181°F after about 13 minutes. After an additional 40 minutes, the polymerization reaction was quenched by adding the polymer cement dropwise into a bucket containing about 8 L of isopropyl alcohol (IPA) and 15 g of 2,6-di-tert-butyl-4-methylphenol. The polymer was coagulated, drum-dried, and analyzed, and the analytical results are reported in Table I.

[0121] Sample 3: Synthesis of non-functional branched SBR A batch of SBR cement was prepared as described for Sample 1, except that 4.23 mL of potassium tertiary amylate (KTA) (0.9 M in cyclohexane, 0.28 equivalents relative to Li) was added to the reactor immediately after dosing. The batch temperature peaked at about 182°F after about 14 minutes. After an additional 40 minutes, the polymerization reaction was quenched by adding the polymer cement dropwise into a bucket containing about 8 L of isopropyl alcohol (IPA) and 15 g of 2,6-di-tert-butyl-4-methylphenol. The polymer was coagulated, drum-dried, and analyzed, and the analytical results are reported in Table I.

[0122] Sample 4: Synthesis of non-functional branched SBR A batch of SBR cement was prepared as described for Sample 1, except that 5.29 mL of potassium tertiary amylate (KTA) (0.9 M in cyclohexane, 0.35 equivalents relative to Li) was added to the reactor immediately after dosing. The batch temperature peaked at about 176°F after about 13 minutes. After an additional 40 minutes, the polymerization reaction was quenched by adding the polymer cement dropwise into a bucket containing about 8 L of isopropyl alcohol (IPA) and 15 g of 2,6-di-tert-butyl-4-methylphenol. The polymer was coagulated, drum-dried, and analyzed, and the analytical results are reported in Table I.

[0123] [Table 1]

[0124] Samples 1-4 were analyzed as follows: Number average (Mn) and weight average (Mw) molecular weights were determined using a Tosoh Ecosec HLC-8320 GPC system and a Tosoh TSKgel GMHx1-BS column with THF as the solvent. The system was calibrated using polystyrene (PS) and referenced to PS standards. The styrene and vinyl content of the polymers was determined by 400 MHz NMR using CDCl3 as the solvent. Mooney viscosity (ML 1+4 ) was determined at 100°C using a Monsanto Mooney viscometer with a large rotor, a 1 minute pre-time, and a 4 minute run time. NMR was used to determine the mole % of bound styrene, vinyl, and weight % of ethylene oxide.

[0125] Samples 5-11 Sample 5: Synthesis of N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane-functionalized branched SBR A nitrogen-purged, jacketed steel reactor was charged with 2.76 pounds of anhydrous hexane, 2.33 mL of diisopropenylbenzene (5.85 M, 1 equivalent to Li), 2.64 mL of 2,2-bis(2'-tetrahydrofuryl)propane (1.6 M in hexane, 0.31 equivalent to Li), and 9.72 mL of Sec-BuLi (1.4 M in cyclohexane, 2.00 mmol per 100 grams of monomer). The reaction mixture was stirred under an inert atmosphere at 27°C for 30 minutes. The reactor was charged with 0.47 pounds of a mixture of 32.2 wt% styrene in hexane and 6.55 pounds of 20.6 wt% butadiene in hexane. Immediately, 4.23 mL of potassium tert-amylate (KTA) (0.9 M in cyclohexane, 0.28 equivalents to Li) was added to the reactor, and the jacket temperature was set to 60°C. The batch temperature peaked at about 78°C after about 16 minutes. After an additional 40 minutes, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane (2.8 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was allowed to proceed for an additional hour. The polymerization reaction was quenched by adding the polymer cement dropwise to a bucket containing about 8 L of isopropyl alcohol and 15 g of 2,6-di-tert-butyl-4-methylphenol. The resulting polymer was analyzed, and the results of these test methods are reported in Table II.

[0126] Sample 6: Synthesis of N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane-functionalized high molecular weight branched SBR A nitrogen-purged, jacketed steel reactor was charged with 2.63 pounds of anhydrous hexane, 1.66 mL of diisopropenylbenzene (5.85 M, 1 equivalent to Li), 1.88 mL of 2,2-bis(2'-tetrahydrofuryl)propane (1.6 M in hexane, 0.31 equivalent to Li), and 6.94 mL of Sec-BuLi (1.4 M in cyclohexane, 1.43 mmol per 100 grams of monomer). The reaction mixture was stirred under an inert atmosphere at 27°C for 30 minutes. The reactor was charged with 0.47 pounds of a mixture of 32.2 wt% styrene in hexane and 6.55 pounds of 20.6 wt% butadiene in hexane. Immediately, 4.23 mL of potassium tert-amylate (KTA) (0.9 M in cyclohexane, 0.28 equivalents to Li) was added to the reactor, and the jacket temperature was set to 60°C. The batch temperature peaked at about 81°C after about 13 minutes. After an additional 40 minutes, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane (2.8 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was allowed to proceed for an additional hour. The polymerization reaction was quenched by adding the polymer cement dropwise to a bucket containing about 8 L of isopropyl alcohol and 15 g of 2,6-di-tert-butyl-4-methylphenol. The resulting polymer was analyzed, and the results of these test methods are reported in Table II.

[0127] Sample 7: Synthetic 3-(1,3-dimethylbutylidene)aminopropyldiethoxysilane functionalized branched polymer A nitrogen-purged, jacketed steel reactor was charged with 2.63 pounds of anhydrous hexane, 2.33 mL of diisopropenylbenzene (5.85 M, 1 equivalent to Li), 2.64 mL of 2,2-bis(2'-tetrahydrofuryl)propane (1.6 M in hexane, 0.31 equivalent to Li), and 9.72 mL of Sec-BuLi (1.4 M in cyclohexane, 2.00 mmol per 100 grams of monomer). The reaction mixture was stirred under an inert atmosphere at 27°C for 30 minutes. The reactor was charged with 0.47 pounds of a mixture of 32.2 wt% styrene in hexane and 6.68 pounds of 20.2 wt% butadiene in hexane. Immediately, 4.23 mL of potassium tert-amylate (KTA) (0.9 M in cyclohexane, 0.28 equivalents to Li) was added to the reactor, and the jacket temperature was set to 60°C. The batch temperature peaked at about 77°C after about 17 minutes. After an additional 40 minutes, 3-(1,3-dimethylbutylidene)aminopropyldiethoxysilane (2.8 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was allowed to proceed for an additional hour. The polymerization reaction was quenched by adding the polymer cement dropwise to a bucket containing about 8 L of isopropyl alcohol and 15 g of 2,6-di-tert-butyl-4-methylphenol. The resulting polymer was analyzed, and the results of these test methods are reported in Table II.

[0128] Sample 8: Synthesis of hexamethylcyclotrisiloxane-functionalized branched polymers A nitrogen-purged, jacketed steel reactor was charged with 2.79 pounds of anhydrous hexane, 2.33 mL of diisopropenylbenzene (5.85 M, 1 equivalent to Li), 2.64 mL of 2,2-bis(2'-tetrahydrofuryl)propane (1.6 M in hexane, 0.31 equivalent to Li), and 9.72 mL of Sec-BuLi (1.4 M in cyclohexane, 2.00 mmol per 100 grams of monomer). The reaction mixture was stirred under an inert atmosphere at 27°C for 30 minutes. The reactor was charged with 0.47 pounds of a mixture of 32.2 wt% styrene in hexane and 6.52 pounds of 20.7 wt% butadiene in hexane. Immediately, 4.23 mL of potassium tert-amylate (KTA) (0.9 M in cyclohexane, 0.28 equivalents to Li) was added to the reactor, and the jacket temperature was set to 60°C. The batch temperature peaked at about 73°C after about 17 minutes. After an additional 40 minutes, hexamethylcyclotrisiloxane (1.0 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was allowed to proceed for an additional 30 minutes. Note that the addition of hexamethylcyclotrisiloxane caused the polymer cement in the reactor to turn into a gel. The functionalization reaction was quenched by charging 10 mL of IPA to the reactor, and the polymer cement was then added dropwise to a bucket containing about 8 L of isopropyl alcohol and 15 g of 2,6-di-tert-butyl-4-methylphenol. The resulting polymer was analyzed, and the results of these test methods are reported in Table II.

[0129] Sample 9: Synthesis of polydimethylsiloxane-functionalized branched polymers A nitrogen-purged, jacketed steel reactor was charged with 2.92 pounds of anhydrous hexane, 2.33 mL of diisopropenylbenzene (5.85 M, 1 equivalent to Li), 2.64 mL of 2,2-bis(2'-tetrahydrofuryl)propane (1.6 M in hexane, 0.31 equivalent to Li), and 9.72 mL of Sec-BuLi (1.4 M in cyclohexane, 2.00 mmol per 100 grams of monomer). The reaction mixture was stirred under an inert atmosphere at 27°C for 30 minutes. The reactor was charged with 0.47 pounds of a mixture of 32.2 wt% styrene in hexane and 6.40 pounds of 21.1 wt% butadiene in hexane. Immediately, 4.23 mL of potassium tert-amylate (KTA) (0.9 M in cyclohexane, 0.28 equivalents to Li) was added to the reactor, and the jacket temperature was set to 60°C. The batch temperature peaked at about 75°C after about 16 minutes. After an additional 40 minutes, hexamethylcyclotrisiloxane (1.19 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was allowed to proceed for an additional 30 minutes. Note that the addition of polydimethylsiloxane caused the polymer cement in the reactor to turn into a gel. The functionalization reaction was quenched by charging 10 mL of IPA to the reactor, and the polymer cement was then added dropwise to a bucket containing about 8 L of isopropyl alcohol and 15 g of 2,6-di-tert-butyl-4-methylphenol. The polymer was coagulated and drum-dried. The resulting polymer was analyzed, and the results of these test methods are reported in Table II.

[0130] Sample 10: Synthesis of functionalized linear SBR A nitrogen-purged, jacketed steel reactor was charged with 2.95 pounds of anhydrous hexane, 0.47 pounds of 32.2 wt.% styrene in hexane, and 6.37 pounds of 21.2 wt.% butadiene in hexane. The reactor was then charged with n-butyllithium (3.54 mL, 1.6 M in hexane, 0.833 mmol per 100 grams of monomer), followed by 2,2-bis(2'-tetrahydrofuryl)propane (1.77 mL, 1.6 M in hexane, 0.5 equivalents relative to Li), and the jacket temperature was set to 60°C. The batch temperature peaked at about 72°C after about 20 minutes. After an additional 30 minutes, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane (2.8 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was allowed to proceed for an additional hour. The polymerization reaction was quenched by adding the polymer cement dropwise to a bucket containing approximately 8 L of isopropyl alcohol and 15 g of 2,6-di-tert-butyl-4-methylphenol. The resulting polymer was coagulated and drum-dried. The resulting polymer was analyzed, and the results of these test methods are reported in Table II.

[0131] Sample 11: Synthesis of functionalized linear SBR A nitrogen-purged, jacketed steel reactor was charged with 5.22 pounds of anhydrous hexane, 0.31 pounds of 32.2 wt.% styrene in hexane, and 4.25 pounds of 21.2 wt.% butadiene in hexane. The reactor was then charged with n-butyllithium (0.72 mL, 2.5 M in hexane, 0.398 mmol per 100 grams of monomer), followed by 2,2-bis(2'-tetrahydrofuryl)propane (1.02 mL, 1.6 M in hexane, 0.9 equivalents relative to Li), and the jacket temperature was set to 60°C. The batch temperature peaked at about 63°C after about 28 minutes. After an additional 90 minutes, N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane (2.8 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was allowed to proceed for an additional hour. The polymerization reaction was quenched by adding the polymer cement dropwise to a bucket containing approximately 8 L of isopropyl alcohol and 15 g of 2,6-di-tert-butyl-4-methylphenol. The resulting polymer was coagulated and drum-dried. The resulting polymer was analyzed, and the results of these test methods are reported in Table II.

[0132] [Table 2] * Due to the very high gel content in Example 7, the functional groups / chains were not determined due to potential inaccuracies in the concentration of functional groups. * The functional groups / chains of Examples 8 and 9 were not determined due to the lack of available methods to determine the concentration of functional groups.

[0133] Samples 5-11 were analyzed as follows. GPC-MALS data were collected using a Tosoh EcoSEC GPC system and a Wyatt DAWN-Heleos II MALS detector. Each sample was dissolved in THF at approximately 1 mg / mL. Samples were eluted through two Tosoh TSKgel GMHxl-BS columns at 1 mL / min with a column oven temperature of 40°C. Absolute molecular weight values ​​were calculated using Wyatt OMNISEC software and a dn / dc value of 0.155 mL / g. The styrene and vinyl content of the polymers was determined by 400 MHz 1H NMR using CDCl3 as the solvent. The Mooney viscosity (ML) of the polymer samples was 0.155 mL / g. 1+4 ) was determined at 100 °C using a Monsanto Mooney viscometer with a large rotor, a 1-minute preparatory time, and a 4-minute running time. Total nitrogen (TN) analysis was performed (in triplicate) on solidified samples using a Mitsubishi Chemical Analytech NSX-2100 Elemental Analyzer System.

[0134] Samples 12-16 Synthesis and stabilization of multifunctional branched polymers A nitrogen-purged, jacketed stainless steel reactor was charged with 2.89 pounds of anhydrous hexane, 2.33 mL of diisopropenylbenzene (5.85 M, 1 equivalent relative to Li), 2.64 mL of 2,2-bis(2'-tetrahydrofuryl)propane (1.6 M in hexane, 0.31 equivalent relative to Li), and 9.72 mL of sec-BuLi (1.4 M in cyclohexane, 2.00 mmol per 100 grams of monomer). After stirring the reaction mixture under an inert atmosphere at 27°C for 30 minutes, 0.47 pounds of 32.2 wt% styrene in hexane and 6.43 pounds of 21.0 wt% butadiene in hexane were mixed together in a charge can and then charged to the reactor, followed by the immediate addition of 4.23 mL of potassium tert-amylate (KTA) (0.9 M in cyclohexane, 0.28 equivalent relative to Li). The jacket temperature was set at 60°C, and the solution temperature and reactor pressure were monitored by sensors located inside the vessel. The batch temperature peaked at about 86°C after about 16 minutes. After an additional 40 minutes, 4.13 mL of 3-(1,3-dimethylbutylidene)aminopropyldiethoxysilane (3.1 M, 1 equivalent relative to Li) was added as a functionalizing agent, and the reaction was continued for an additional 60 minutes. A sample of the product cement was then collected via needle puncture into a dried, purged, and sealed 800 mL bottle. The properties of a drum-dried sample of the polymer before stabilization were as follows: Tg = -43°C, Mn = 217 kg / mol, Mw = 334 kg / mol, Mp = 287 kg / mol, Mw / Mn = 1.54, and a coupling rate of 77%.

[0135] The prepared SBR polymer cement introduced into bottles was quenched by adding 3 mL of IPA / BHT solution to each bottle. Then, to each of two bottles containing approximately 400 g of cement, a stabilizer solution was added, as shown in Table III. The stabilizers used were triethoxyoctylsilane, 3.18 M (pure) (triethoxyoctylsilane, OTES), ethyl hexanoic acid, 6.26 M (pure) (ethyl hexanoic acid, EHA), triphenylsilanol, 0.2 M in 20% ethanol in cyclohexane (triphenylsilanol, TPS), and diphenylsilanediol, 0.1 M in 20% ethanol in cyclohexane (diphenylsilanediol, DPSDO).

[0136] The bottles were agitated in a 50°C water bath for 30 minutes. The cement from the bottle pairs was then steam-desolventized using a mini steam desolventizer. 15 g of Polyquat was added to the water (for Sample 1, the same water was used for subsequent samples, with 8 g of Polyquat added each time) and steam was used to heat the water to above 80°C. The agitation speed was set as high as possible without causing splashing, and the cement was poured from the bottles into the desolventizer in a slow, controlled manner, resulting in a crumbled material. The devolatilized polymer was collected and dried in a 70°C oven for 12 hours. A portion of the material was then oven-aged at 100°C for 48 hours. The unaged polymer was characterized by GPC, NMR, and DSC, and both the unaged and aged samples were analyzed to determine their Mooney viscosity and T 80 The values ​​were measured and the results are reported in Table III.

[0137] [Table 3] * Values ​​could not be determined due to extreme sample deterioration

[0138] Various modifications and alterations that do not depart from the scope and spirit of the invention will be apparent to those skilled in the art. This invention is not to be duly limited to the illustrative embodiments set forth herein.

Claims

1. 1. A method for preparing a branched polymer, said method comprising: (i) preparing a multi-site initiator by reacting a polyalkenyl compound with an alkyllithium compound; (ii) introducing said multi-site initiator, monomer, and potassium alkoxide to form a polymerization mixture comprising a molar ratio of potassium to lithium greater than 0.150:1; (iii) polymerizing the monomer to form a branched polymer.

2. 2. The method of claim 1, wherein the polyalkenyl compound is diisopropenyl benzene.

3. 3. The method of claim 1, wherein the alkyllithium is sec-butyllithium.

4. 4. The method of any one of claims 1 to 3, wherein the step of preparing a multi-site initiator comprises aging the initiator at a temperature of from about 25 to about 100°C for more than 1 minute.

5. 5. The method of any one of claims 1 to 4, wherein the step of preparing a multi-site initiator comprises aging the initiator in the presence of a Lewis base.

6. The method of any one of claims 1 to 5, wherein the Lewis base is 2,2-bis(2-oxolanyl)propane.

7. 7. The method of any one of claims 1 to 6, wherein the step of preparing a multi-site initiator comprises aging the initiator in a reaction mixture comprising a solvent in which the initiator is soluble.

8. 8. The method of any one of claims 1 to 7, wherein the potassium alkoxide is selected from the group consisting of potassium tert-amylate and potassium tert-butoxide.

9. The method of any one of claims 1 to 8, wherein the monomers are conjugated diene monomers and optionally include vinyl aromatic monomers.

10. 10. The method of any one of claims 1 to 9, wherein the step of introducing the multi-site initiator, the monomer, and the potassium alkoxide is carried out using a solvent in which at least one of the multi-site initiator, the monomer, and the potassium alkoxide is soluble, thereby forming a polymerization mixture.

11. 11. The method of any one of claims 1 to 10, wherein the step of polymerizing the monomers forms a branched polymer having multiple reactive chain ends.

12. 12. The method of any one of claims 1 to 11, further comprising the step of reacting the branched polymer having multiple reactive chain ends with a functionalizing agent, thereby forming a branched functionalized polymer.

13. The method of any one of claims 1 to 12, wherein the functionalizing agent is a hydrocarbyloxysilane.

14. wherein the functionalizing agent is a compound of the formula 【Chemistry 1】 wherein R ２ , R ３ , and R ７ is a monovalent organic group, and R ４ is a divalent organic group, and R ５ and R ６ The method of any one of claims 1 to 13, wherein each is independently a hydrocarbyloxy group or a hydrocarbyl group.

15. 15. The method of any one of claims 1 to 14, wherein the functionalizing agent is selected from the group consisting of N-(1,3-dimethylbutylidene)-3-(triethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(triethoxysilyl)-1-propanamine, N-ethylidene-3-(triethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(triethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(triethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(triethoxysilyl)-1-propanamine.

16. 16. The method of any one of claims 1 to 15, wherein the functionalizing agent is selected from the group consisting of N-(1,3-dimethylbutylidene)-3-(trimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(trimethoxysilyl)-1-propanamine, N-ethylidene-3-(trimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(trimethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(trimethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(trimethoxysilyl)-1-propanamine.

17. 17. The method of any one of claims 1 to 16, wherein the functionalizing agent is selected from the group consisting of methyldiethoxy compounds such as, but not limited to, N-(1,3-dimethylbutylidene)-3-(methyldiethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(methyldiethoxysilyl)-1-propanamine, N-ethylidene-3-(methyldiethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(methyldiethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(methyldiethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(methyldiethoxysilyl)-1-propanamine.

18. 18. The method of any one of claims 1 to 17, wherein the functionalizing agent is selected from the group consisting of ethyldimethoxy compounds such as, but not limited to, N-(1,3-dimethylbutylidene)-3-(ethyldimethoxysilyl)-1-propanamine, N-(1-methylethylidene)-3-(ethyldimethoxysilyl)-1-propanamine, N-ethylidene-3-(ethyldimethoxysilyl)-1-propanamine, N-(1-methylpropylidene)-3-(ethyldimethoxysilyl)-1-propanamine, N-(4-N,N-dimethylaminobenzylidene)-3-(ethyldimethoxysilyl)-1-propanamine, and N-(cyclohexylidene)-3-(ethyldimethoxysilyl)-1-propanamine.

19. wherein the functionalizing agent is a compound of the formula 【Chemistry 2】 wherein R ４ is a divalent organic group, and R ５ and R ６ are each independently a hydrocarbyloxy group or a hydrocarbyl group, and R ５ is a monovalent organic group and A is selected from the group consisting of carboxylic acid esters, cyclic tertiary amines, acyclic tertiary amines, pyridines, silazanes, and sulfide groups.

20. 20. The method of any one of claims 1 to 19, wherein the functionalizing agent is selected from the group consisting of N,N-bis(trimethylsilyl)aminopropylmethyldimethoxysilane, 1-trimethylsilyl-2,2-dimethoxy-1-aza-2-silacyclopentane, N,N-bis(trimethylsilyl)aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminopropylmethyldiethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethylmethyldimethoxysilane, and N,N-bis(trimethylsilyl)aminoethylmethyldiethoxysilane.

21. The branched polymer has a T ８０ The method according to any one of claims 1 to 20, characterized by:

22. 22. The method of any one of claims 1 to 21, wherein a stabilizer is introduced into the branched functionalized polymer after the step of reacting the branched polymer with a functionalizing agent, thereby forming a branched functionalized polymer.

23. The method of any one of claims 1 to 22, wherein the stabilizing agent is an aryl silanol.

24. 24. The method of any one of claims 1 to 23, wherein the amount of aryl silanol introduced is from about 1 to about 7 moles of aryl silanol per mole of lithium introduced into the polymerization mixture.

25. 25. The method of any one of claims 1 to 24, wherein the aryl silanol is selected from the group consisting of triphenyl silanol, diphenyl silane diol, and phenyl silane triol.

26. 26. The method of any one of claims 1 to 25, wherein after the step of reacting the branched polymer with a functionalizing agent, thereby forming a branched functionalized polymer, an aryl silanol and a silane comprising a hydrolyzable group that forms an acidic species upon hydrolysis are introduced into the branched functionalized polymer.

27. 27. The method of any one of claims 1 to 26, wherein the molar ratio of the aryl silanol to the silane having a hydrolyzable group that forms an acidic species upon hydrolysis is from about 0.5:1 to about 4:

1.

28. The method of any one of claims 1 to 27, further comprising isolating the branched functionalized polymer from the polymerization mixture.

29. A branched polymer formed by the method of any one of claims 1 to 28.

30. 30. The branched polymer of any one of claims 1 to 29, wherein the branched polymer can be characterized by a weight average molecular weight of greater than 250 kg / mol.

31. The branched polymer of any one of claims 1 to 30, wherein the branched polymer can be characterized by a vinyl content of greater than 10%.

32. 32. The branched polymer of any one of claims 1 to 31, wherein the branched polymer can be characterized by greater than 20% bound styrene.

33. 33. The branched polymer of any one of claims 1 to 32, wherein the branched polymer can be characterized by a T80 (ASTM D1646-19A) of greater than 2 minutes.

34. 34. The branched polymer of any one of claims 1 to 33, wherein the branched polymer can be characterized by a Mooney viscosity (ML 1+4 @ 100°C) of greater than 20.

35. 35. The branched polymer of any one of claims 1 to 34, wherein the branched polymer can be characterized by a Tg (ASTM E1356-08) of less than -20°C.

36. A vulcanizable composition comprising the functionalized branched polymer of any one of claims 1 to 35.

37. A vulcanizate prepared by vulcanizing the vulcanizable composition of any one of claims 1 to 36.

38. A tire component prepared from the vulcanizable composition of any one of claims 1 to 37.

39. A tire tread prepared from the vulcanizable composition of any one of claims 1 to 38.

40. 1. A vulcanizable composition comprising: (i) a branched polymer, (a) providing for the preparation of a multi-site initiator by reacting a polyalkenyl compound with an alkyllithium compound; (b) introducing the multi-site initiator, the monomer, and the potassium alkoxide to form a polymerization mixture comprising a molar ratio of potassium to lithium greater than 0.150:1; (c) polymerizing the monomer to form a branched polymer; and (ii) silica; and (iii) a curing agent.

41. The vulcanizable composition of any one of claims 1 to 40, further comprising a silica coupling agent.

42. 42. The vulcanizable composition of any one of claims 1 to 41, further comprising a silica dispersant.

43. The silica dispersant is an alkylalkoxysilane, hydrogenated or non-hydrogenated C ５ or C ６ Fatty acid esters of sugars, hydrogenated or non-hydrogenated C ５ or C ６ 43. The vulcanizable composition according to any one of claims 1 to 42, wherein the polyoxyethylene derivatives of fatty acid esters of sugars and esters of polyols are selected from the group consisting of polyoxyethylene derivatives of fatty acid esters of sugars and esters of polyols, and mixtures thereof.

44. 44. The vulcanizable composition of any one of claims 1 to 43, wherein said silica dispersant is glycol monostearate.

45. The vulcanizable composition of any one of claims 1 to 44, wherein the silica dispersant is a metal glycerolate.

46. 46. ​​The vulcanizable composition of any one of claims 1 to 45, wherein the metal glycerolate is zinc glycerolate.

47. 47. The vulcanizable composition of any one of claims 1 to 46, wherein the vulcanizable composition comprises greater than 70 parts by weight of silica per 100 parts by weight of rubber.

48. 48. The vulcanizable composition of any one of claims 1 to 47, wherein the vulcanizable composition comprises from about 2% to about 30% by weight of silica coupling agent, based on the weight of the silica.

49. 49. The vulcanizable composition of any one of claims 1 to 48, wherein the vulcanizable composition comprises from about 0.1 wt% to about 30 wt% of a silica dispersant, based on the weight of the silica.

50. 50. The vulcanizable composition of any one of claims 1 to 49, wherein the branched polymer is a functionalized branched polymer formed by reacting the branched polymer with a functionalizing agent.

51. A vulcanizate prepared by vulcanizing the vulcanizable composition of any one of claims 1 to 50.

52. A tire component prepared from the vulcanizable composition of any one of claims 1 to 51.

53. A tire tread prepared from the vulcanizable composition of any one of claims 1 to 52.

54. 1. A method for forming a vulcanizable composition, said method comprising: (i) providing a branched polymer, the branched polymer comprising: (a) providing for the preparation of a multi-site initiator by reacting a polyalkenyl compound with an alkyllithium compound; (b) introducing the multi-site initiator, the monomer, and the potassium alkoxide to form a polymerization mixture comprising a molar ratio of potassium to lithium greater than 0.150:1; (c) polymerizing the monomers to form a branched polymer; (ii) providing silica; (iii) providing a curing agent; (iv) mixing the branched polymer, the silica, and the curing agent to form the vulcanizable composition.

55. 55. The method of any one of claims 1 to 54, wherein the branched polymer is a functionalized branched polymer formed by reacting the branched polymer with a functionalizing agent.

56. 56. The method of any one of claims 1 to 55, further comprising providing a silica coupling agent, and further comprising mixing the branched polymer, the silica, and the silica coupling agent.

57. 57. The method of any one of claims 1 to 56, further comprising providing a silica dispersant, and further comprising mixing the branched polymer, the silica, and the silica dispersant.

58. 58. The method of any one of claims 1 to 57, further comprising providing a silica coupling agent and a silica dispersing agent, and further comprising mixing the branched polymer, the silica, the silica dispersing agent, and the silica coupling agent.

59. The silica dispersant is an alkylalkoxysilane, hydrogenated or non-hydrogenated C ５ or C ６ Fatty acid esters of sugars, hydrogenated or non-hydrogenated C ５ or C ６ 59. The method of any one of claims 1 to 58, wherein the polyoxyethylene derivatives of fatty acid esters of sugars and esters of polyols are selected from the group consisting of: polyoxyethylene derivatives of fatty acid esters of sugars and esters of polyols, and mixtures thereof.

60. 60. The method of any one of claims 1 to 59, wherein the silica dispersant is glycol monostearate.

61. 61. The method of any one of claims 1 to 60, wherein the silica dispersant is a metal glycerolate.

62. 62. The method of any one of claims 1 to 61, wherein the metal glycerolate is zinc glycerolate.

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