Schiff base oligomers

Abstract

Embodiments of the present disclosure relate to Schiff base oligomers and uses thereof. In at least one embodiment, the oligomers are represented by formula (IV), where R 9 Each instance of R in formula (IV) is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether. 28 and R 29 Each instance of R in formula (IV) is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl. 33 Each instance of R in formula (IV) is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond. 41 Each instance of is independently -NH- or a bond; 40 Each instance of R in formula (IV) is independently -NH- or -NH-NH-. 42 Each instance of is independently -NH- or a bond; 43 Each instance of is independently -NH- or -NH-NH-.

Description

[Technical Field]

[0001] Aspects of the present disclosure relate to Schiff base oligomers and uses thereof. [Background technology]

[0002] Metals such as steel, aluminum, aluminum alloys, and galvanized metals used in the manufacture of aircraft, spacecraft, and other machinery can be susceptible to corrosion. Chromates, such as the zinc salt of hexavalent chromium, have been used as corrosion inhibitors in corrosion-protective coatings such as paints, sealants, and wash primers. It would be desirable to reduce the amount of chromate used in coatings and other applications.

[0003] Several non-chromate corrosion inhibitors have been proposed. For example, Gupta et al., "Green Schiff's bases as corrosion inhibitors for mild steel in 1 M HCl solution: experimental and theoretical approach," RSC Adv., 2016, 6, 102076-102087, discloses a cysteine Schiff base with a molecular weight of 255.05 or less as a corrosion inhibitor. Rasool et al., "Coordination Polymers: Preparation, Physicochemical Characterization, Thermal and Biological Evaluation of Thiosemicarbazide Polychelates," J Inorg Organomet Polym 25, 763-771 (2015), discloses a Schiff base polymer complexed with Co, Ni, Cu, or Zn transition metals that has antibacterial and antifouling properties.

[0004] Overall, hexavalent chromium alternative corrosion inhibitors may have limitations compared to those containing hexavalent chromium, and their adhesion may be insufficient to the underlying substrate and the coating disposed thereon. Additionally, alternative corrosion inhibitors often do not meet aerospace performance requirements.

[0005] New corrosion inhibitors are needed to provide improved coatings for protecting metal surfaces from corrosion with little or no hexavalent chromium. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Gupta et al. "Green Schiff's bases as corrosion inhibitors for mild steel in 1 M HCl solution: experimental and theoretical approach" RSC Adv., 2016, 6, 102076-102087 [Non-patent document 2] Rasool et al. “Coordination Polymers: Preparation, Physicochemical Characterization, Thermal and Biological Evaluation of Thiosemicarbazide Polychelates” J Inorg Organomet Polym 25, 763-771 (2015) Summary of the Invention [Problem to be solved by the invention]

[0007] Aspects of the present disclosure relate to Schiff base oligomers and uses thereof. [Means for solving the problem]

[0008] In at least one embodiment, the oligomer has formula (IV): [ka] wherein: R 9 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 28 and R 29 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 33 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 41 Each instance of is independently -NH- or a bond; 40 each instance of is independently -NH- or -NH-NH-; R 42 Each instance of is independently -NH- or a bond; 43 each instance of is independently -NH- or -NH-NH-; each instance of z and t is an integer from 1 to 50; R 44 is a hydroxyl or hydroxy-substituted alkyl, or has the structure: [ka] wherein: R 1 is hydrogen or silyl, R 2 and R 3 are independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 31 is selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 50 is -NH- or a bond, and R 32 is -NH- or -NH-NH-, R 34is -NH- or a bond, and R 35 is -NH- or -NH-NH-, x is an integer from 1 to 50, R 30 is hydrogen, silyl, or has the structure: [ka] wherein: R 9’ is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 44’ is hydroxyl or hydroxy-substituted alkyl. DETAILED DESCRIPTION OF THE INVENTION

[0009] Aspects of the present disclosure relate to Schiff base oligomers and their uses. The Schiff base oligomers may have one or more silyl groups to provide bonding to metals to prevent corrosion and to enhance adhesion to metals and metal oxides. In general, Schiff bases are compounds with the general structure R1R2C=NR' (where R'≠H).

[0010] In some embodiments, the Schiff base oligomer comprises two or more repeating units of a Schiff base monomer unit, each Schiff base monomer unit having at least one thiocarbonyl group. The Schiff base oligomer may have a linking unit connecting two or more repeating units of the Schiff base monomer unit. For example, the linking unit may have a hydroxyl group. Alternatively, the linking unit may be a urea-containing unit.

[0011] The Schiff base oligomer may be dispersible in a solvent. The Schiff base oligomer may be a composition comprising (e.g., dispersed or ionically bound to) one or more metals. For example, the metal may be a cationic species of a transition metal.

[0012] In some embodiments, the Schiff base oligomers function as a film-forming coating in which the Schiff base monomer units inhibit metal corrosion. The Schiff base oligomers provide improved adhesion of the Schiff base oligomer to the surface of the metal and increased concentration of the inhibitor at the surface compared to conventional corrosion inhibitors. Compared to small molecule Schiff bases, such as small molecule Schiff bases of less than 300 daltons, the Schiff base oligomers can provide a sustained- or controlled-release system that can provide long-term corrosion protection due to slow dissolution or slow hydrolysis of the polymer or oligomer.

[0013] In certain embodiments, the Schiff base oligomer has a molecular weight of 300 daltons or greater, such as 500 daltons or greater, such as 1,000 daltons or greater, such as 10,000 daltons or greater, such as 15,000 daltons or greater.

[0014] Schiff base oligomers can interact with metals (e.g., compositions and / or metal substrates) through tertiary nitrogen atoms and thiocarbonyl sulfur atoms. By having multiple groups on the same molecule that can interact with (e.g., chelate) metals, when the first group interacts with, for example, a metal surface, each subsequent group can interact with a lower enthalpy loss, lowering the barrier to formation, increasing stability, and ultimately improving adhesion of the Schiff base oligomer compared to conventional corrosion inhibitors. Furthermore, in instances where the Schiff base oligomer has silyl end-capping, the silyl groups can provide additional adhesion of the Schiff base oligomer to the substrate via one or more atoms of the silyl group.

[0015] In certain embodiments, Schiff base oligomers have good adhesion to metal (e.g., pure metal, metal alloy, and / or metal oxide) surfaces and provide corrosion protection by coordinating to the surface via imine, thiocarbonyl, secondary hydroxyl, and / or urea backbone groups. Furthermore, the secondary hydroxyl groups can react with epoxy and urethane primers to provide a bond layer. For example, the hydroxyl groups of the Schiff base oligomer can react with the isocyanate groups of the urethane primer. The oligomers provide multiple functional binding sites that help provide the necessary durability and have a glass transition temperature (Tg) low enough to avoid crystallization (e.g., about -25°C or lower).

[0016] Adhesion can be determined as described in Rasool et al., J. Inorg. Organomet Polym 2015, Vol. 15, pp. 763-771, which provides detailed IR (Table 2), H NMR (Section 5.3), and electronic spectra (Section 5.4 and Table 3) of free Schiff base complexes and related metal complexes. The data confirm the formation of metal bonds to nitrogen and oxygen atoms in the complexes. The IR stretching frequency ranges from 8 to 25 cm upon metal-nitrogen or metal-oxygen bond formation. -1 Schiff bases are polymeric species that form complexes to individual metal atoms.

[0017] In certain embodiments, the Schiff base oligomer comprises polymeric thiosemicarbazone monomer units having imine and thiocarbonyl groups and one or more optional secondary hydroxyl groups and / or one or more urea-containing units to provide adhesion to metal substrates.

[0018] Schiff base oligomers can be reacted with ethers, such as polyethylene glycol diglycidyl ether, diglycidyl ether, or other suitable ethers, to enhance the dispersibility of the Schiff base oligomer. Dispersible Schiff base polymers (e.g., water-soluble, water-dispersible, aqueous-organic solvent blend-soluble, aqueous-organic solvent blend-dispersible, organic solvent-soluble, organic solvent-dispersible) have good adhesion to metal and metal oxide surfaces and provide corrosion protection by coordination to the surface via imine, thiocarbonyl / carbonyl, and / or hydroxyl groups. Additionally, hydroxyl groups, such as secondary hydroxyl groups, can react with epoxy and urethane primers to form a bond layer. For example, available secondary hydroxyl groups can react with isocyanates in polyurethane coating formulations. Covalent bond formation may be desirable for bonding to primers. The polymer provides multiple functional binding sites, which helps provide the necessary durability and has a sufficiently low Tg (e.g., about -25°C or lower) to avoid crystallization during use in cold environments, for example. The Schiff substrates of the present disclosure can provide a suitable corrosion-resistant coating for metals experiencing the temperature ranges encountered on commercial and defense aircraft, where ambient air temperatures at 40,000 feet can be -40°F or lower.

[0019] Method for producing Schiff base oligomers A method for producing a Schiff base oligomer includes reacting a Schiff base monomer having at least one thiocarbonyl group and at least two terminal -NH groups with a dicarbonyl to form a first reaction product. For example, the Schiff base monomer can be thiocarbazide or thiosemicarbazide. The first reaction product has two terminal -NH groups. In some embodiments, the Schiff base monomer can be heated, followed by the addition of a dicarbonyl and an acid (e.g., a strong acid such as HCl) to form a reaction mixture. The reaction mixture can be cooled (and optionally cooled below ambient temperature) to form a first reaction product.

[0020] The first reaction product can be reacted with one or more epoxy-containing compounds to form a second reaction product having one or more hydroxyl groups. Alternatively, the first reaction product can be reacted with one or more isocyanate-containing compounds to form a second reaction product having one or more urea-containing linkages and one or more monomer units having a thiocarbonyl group. The reaction of the first reaction product with the epoxy-containing compound (or isocyanate-containing compound) can be carried out in the presence of a base (such as NaOH) and / or an acid (such as barbituric acid).

[0021] Schiff base oligomers can contain two or more Schiff base monomer units. The Schiff base monomer used can be thiosemicarbazide, thiocarbazide, or any suitable thiocarbonyl-containing compound with two or more terminal (-NH) groups. For example, Schiff base oligomers can be made by reacting a thiocarbazide or thiosemicarbazide with a dicarbonyl containing two or more carbonyl groups. A carbonyl containing two or more carbonyl groups is referred to herein as a "dicarbonyl." The carbonyl group can be an aldehyde, a ketone, or a combination thereof. The carbonyl group of the dicarbonyl can react with the nitrogen atom at either end of the thiocarbazide or thiosemicarbazide. The dicarbonyl can link two or more thiocarbazides or thiosemicarbazides together to form a first reaction product.

[0022] Alternatively, Schiff base oligomers can be made by reacting thiocarbazide or thiosemicarbazide with a diisocyanate containing two or more isocyanate groups. A carbonyl containing two or more isocyanate groups is referred to herein as a "diisocyanate." The carbonyl group of the diisocyanate can react with either terminal nitrogen atom of the thiocarbazide or thiosemicarbazide. The diisocyanate can link two or more thiocarbazides or thiosemicarbazides together to form a first reaction product.

[0023] The terminal amine group of the first reaction product can react with a diepoxide to form a Schiff base oligomer. The diepoxide can enhance dispersibility. For example, a diepoxide having a hydrophilic group can enhance the dispersibility of the Schiff base oligomer in an aqueous solvent or an aqueous-organic blend solvent. For example, an epoxy having a hydrophobic group (e.g., an organic group such as an alkyl or aryl group) can enhance the dispersibility of the Schiff base oligomer in an organic solvent. Epoxies that can enhance aqueous dispersibility include, for example, phenol glycidyl ether, lauryl alcohol glycidyl ether, glycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether. In certain embodiments, the epoxy is a low molecular weight epoxy (eg, about 600 daltons or less), such as a low molecular weight polyethylene glycol diglycidyl ether.

[0024] Alternatively, the terminal amine group of the first reaction product can react with a diisocyanate to form a Schiff base oligomer. The diisocyanate can enhance dispersibility. For example, a diisocyanate having a hydrophilic group can enhance the dispersibility of the Schiff base oligomer in an aqueous solvent or an aqueous-organic blend solvent. For example, a diisocyanate having a hydrophobic group (e.g., an organic group such as an alkyl or aryl group) can enhance the dispersibility of the Schiff base oligomer in an organic solvent. Examples of diisocyanates that can enhance aqueous dispersibility include methylene-bis(phenylisocyanate) (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), naphthalene diisocyanate (NDI), methylene-bis-cyclohexyl isocyanate (HMDI) (hydrogenated MDI), and isophorone diisocyanate (IPDI).

[0025] In some embodiments, the Schiff base oligomer is a silyl-end-capped Schiff base oligomer. The Schiff base oligomer may have one or more terminal amine groups. The one or more terminal amine groups can be reacted with a silyl-containing end-blocking compound to obtain a silyl-end-capped Schiff base oligomer. For example, the silyl-containing end-blocking can have a reactive moiety (e.g., a leaving group such as an epoxy group or a halogen). In some examples, the silyl-containing end-blocking is an epoxy-containing silyl-containing end-blocking. The silyl-end-capped Schiff base oligomer can provide additional adhesion to a substrate.

[0026] Method for disposing Schiff base oligomers on a substrate In some embodiments, the method includes applying a Schiff base oligomer (e.g., dispersed in a solvent) to a substrate, such as a metal substrate. The Schiff base oligomer can be applied to the metal by spraying, brushing, roller coating, or immersion, for example, to completely coat the surface. The ability to apply the material by various methods allows for the scale-up of this technique. The aircraft industry may use spraying, while automotive companies may use dip baths for automobile frames, and railroad car manufacturers may use roller or brush methods. The Schiff base oligomer can be dispersible in aqueous solvents, organic solvents, or aqueous-organic solvent blends. The functional groups of the Schiff base oligomer can be reacted with other components, for example, to enhance its dispersibility. In comparison, small molecule Schiff bases are often solids and can often only be applied as particles.

[0027] In certain embodiments, the Schiff base oligomers provide corrosion protection for extended periods of time, as determined by pass / fail in a 3000-hour ASTM B117 salt fog exposure test. The Schiff base oligomers can form continuous films that provide corrosion protection for metal surfaces for extended periods of time. The Schiff base oligomers can form coatings to prevent corrosion of metal surfaces in aerospace vehicles, automobiles, trucks, trains, boats, ships, buildings, bridges, and other metal components.

[0028] Schiff base oligomers In some embodiments, the Schiff base oligomer has formula (I): [ka] wherein: R 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 and R 14 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, alkoxyl, aryloxyl, ether, and heterocyclyl; R 9 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and ether; R 28 and R 29 each instance of is independently selected from the group consisting of hydrogen, alkyl, and aryl; R 33 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 41 Each instance of is independently -NH- or a bond; 40 each instance of is independently -NH- or -NH-NH-; R 42Each instance of is independently -NH- or a bond; 43 each instance of is independently -NH- or -NH-NH-; each instance of Q is independently -CH- or oxygen; each instance of n, m, z, and t is an integer independently selected from the group consisting of 1 to 50, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 44 is hydroxyl, hydroxy-substituted alkyl, or has the structure: [ka] wherein: R 1 is hydrogen or silyl, R 2 and R 3 is independently selected from the group consisting of hydrogen, alkyl, and aryl; R 31 is selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 50 is -NH- or a bond, and R 32 is -NH- or -NH-NH-, R 34 is -NH- or a bond, and R 35 is -NH- or -NH-NH-, x is an integer from 1 to 50, e.g., an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 30 is hydrogen, silyl, or has the structure: [ka] wherein: R 4’ , R 5’ , R 6’ , R 7’ , R 8’ , R 10’ , R 11’ , R 12’ , R13’ and R 14’ each is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, alkoxyl, aryloxyl, ether, and heterocyclyl; R 9’ is selected from the group consisting of alkyl, cycloalkyl, heterocyclyl, and ether; R 44’ is hydroxyl or hydroxy-substituted alkyl; each instance of Q' is independently -CH2- or oxygen; Each of n' and m' is an integer from 1 to 50, for example, an integer independently selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0029] In some embodiments, R 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 and R 14 (or R 4 ', R 5 ', R 6 ', R 7 ', R 8 ', R 10 ', R 11’ , R 12’ , R 13’ and R 14’ Each instance of R is independently selected from the group consisting of hydrogen and C-C alkyl. 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 and R 14 (or R 4 ', R 5 ', R 6 ', R 7 ', R 8 ', R 10 ', R11’ , R 12’ , R 13’ and R 14’ ) is hydrogen. In some embodiments, R 28 or R 29 (or R 2 and R 3 Each instance of R is independently selected from the group consisting of hydrogen and C-C alkyl. 28 or R 29 (or R 2 and R 3 ) is hydrogen. In some embodiments, each instance of Q is oxygen.

[0030] In some embodiments, R 41 is -NH-, R 40 is -NH- and / or R 41 If is a bond, R 40 is -NH-NH-. In some embodiments, R 42 is -NH-, R 43 is -NH- and / or R 42 If is a bond, R 43 is -NH-NH-.

[0031] In some embodiments, R 50 is -NH-, R 32 is -NH- and R 50 If is a bond, R 32 is -NH-NH-. In some embodiments, R 34 is -NH-, R 35 is -NH- and R 34 If is a bond, R 35 is -NH-NH-.

[0032] In some embodiments, R 9 (or R 9’ ) independently, C1-C 10 alkyl or polyether. For example, R 9 (or R 9’) may be a polyether selected from polyethylene glycol and polypropylene glycol. The polyethylene glycol or polypropylene glycol may have a molecular weight of about 100 g / mol to about 1,000 g / mol, for example, about 400 g / mol to about 700 g / mol.

[0033] In some embodiments, R 33 (or R 31 ) is a bond. 33 (or R 31 ) are instances of C1-C 10 In some embodiments, R 33 (or R 31 Each instance of is independently selected from phenyl. For example, phenyl is a group of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0034] In some embodiments, R 30 and R 1 is hydrogen. In some embodiments, R 30 and R 1 is a silyl. For example, the silyl can be a glycidyl ether silyl. In some embodiments, the silyl has the formula: [ka] where R45 , R 46 and R 47 is hydrogen and C1-C 20 alkyl, e.g., C1-C5 alkyl; R 48 is selected from the group consisting of (divalent) alkyl, cycloalkyl, ether, and aryl. In some embodiments, R 48 is alkyl or ether. In some embodiments, silyl is [ka] or [ka] is.

[0035] In some embodiments, the Schiff base oligomer has formula (II): [ka] wherein: The wavy line is a line that interrupts a single bond and indicates the point of attachment of the second wavy line to the oligomer represented by formula (II) (in other words, R 36 is R 14 (attached to the alpha carbon of R 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 , R 14 , R 17 , R 18 , R 19 , R 20 , R 21 , R 23 , R 24 , R 25 , R 26 and R 27 each is independently selected from the group consisting of alkyl, cycloalkyl, alkoxyl, aryloxyl, heterocyclyl, and ether; R 9 and R 22 each is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 2 , R 3 , R 15 , R 16 , R 28 and R 29 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 31 , R 33 and R 51 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 34 , R 37 , R 38 , R 41 , R 42 and R 50 Each instance of is independently -NH- or a bond; 32 , R 35 , R 36 , R 39 , R 40 and R 43 each instance of is independently -NH- or -NH-NH-; each instance of Q is independently -CH- or oxygen; each instance of n, m, p, q, x, y, and z is an integer independently selected from the group consisting of 1 to 50, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 1 and R 30 is independently selected from the group consisting of hydrogen and silyl.

[0036] In some embodiments, each of x, y, and z in formula (II) is the integer 1.

[0037] In some embodiments, R of formula (II) 4 , R 5 , R 6 , R 7 , R8 , R 10 , R 11 , R 12 , R 13 , R 14 , R 17 , R 18 , R 19 , R 20 , R 21 , R 23 , R 24 , R 25 , R 26 and R 27 Each instance of R is independently selected from the group consisting of hydrogen and C1-C5 alkyl. 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 , R 14 , R 17 , R 18 , R 19 , R 20 , R 21 , R 23 , R 24 , R 25 , R 26 and R 27 Each instance of R is hydrogen. 2 , R 3 , R 15 , R 16 , R 28 and R 29 Each instance of R is independently selected from the group consisting of hydrogen and C1-C5 alkyl. 2 , R 3 , R 15 , R 16 , R 28 and R 29 Each instance of Q is hydrogen. In some embodiments, each instance of Q is oxygen.

[0038] In some embodiments, R of formula (II) 34 , R 37 , R 38 , R 41 , R 42and R 50 are each -NH-, then R 32 , R 35 , R 36 , R 39 , R 40 and R 43 are each -NH-. In some embodiments, R 34 , R 37 , R 38 , R 41 , R 42 and R 50 If is a bond, R 32 , R 35 , R 36 , R 39 , R 40 and R 43 are -NH-NH-, respectively.

[0039] In some embodiments, R of formula (II) 9 and R 22 Each instance of C1-C 10 alkyl or polyether. For example, R 9 or R 22 may be a polyether selected from polyethylene glycol and polypropylene glycol. The polyethylene glycol or polypropylene glycol may have a molecular weight of about 100 g / mol to about 1,000 g / mol, for example, about 400 g / mol to about 700 g / mol.

[0040] In some embodiments, R of formula (II) 31 , R 33 and R 51 Each instance of R is a bond. 31 , R 33 and R 51 Each instance of C1-C 10 In some embodiments, R 31 , R 33 and R 51 Each instance of each instance of is independently selected from phenyl. For example, phenyl is a group of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0041] In some embodiments, R of formula (II) 1 and R 30 is hydrogen. In some embodiments, R 1 and R 30 is a silyl. For example, the silyl can be a glycidyl ether silyl. In some embodiments, the silyl has the formula: [ka] where R 45 , R 46 and R 47 is hydrogen and C1-C 20 alkyl, e.g., C1-C5 alkyl; R 48 is selected from the group consisting of (divalent) alkyl, cycloalkyl, ether, and aryl. In some embodiments, R 48 is alkyl or ether. In some embodiments, silyl is [ka] or [ka] is.

[0042] In some embodiments, the Schiff base oligomer has formula (III): [ka] wherein: The wavy line is a line interrupting a single bond shown to indicate the point of attachment at the second wavy line of the oligomer represented by formula (III) (in other words, the NH group adjacent to the wavy line is an R 14 (attached to the alpha carbon of R 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 , R 14 , R 17 , R 18 , R 19 , R 20 , R 21 , R 23 , R 24 , R 25 , R 26 and R 27 are independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, alkoxyl, aryloxyl, heterocyclyl, and ether; R 9 and R 22 each is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 2 , R 3 , R 15 , R 16 , R 28 and R 29 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 31 , R 32 and R 33 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; each instance of n, m, p, and q is an integer independently selected from the group consisting of 1 to 50, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 1 and R 30 is independently selected from the group consisting of hydrogen and silyl.

[0043] In some embodiments, R of formula (III) 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 , R 14 , R 17 , R 18 , R 19 , R 20 , R 21 , R 23 , R 24 , R 25 , R 26 and R 27 Each instance of R is independently selected from the group consisting of hydrogen and C1-C5 alkyl. 4 , R 5 , R 6 , R 7 , R 8 , R 10 , R 11 , R 12 , R 13 , R 14 , R 17 , R 18 , R 19 , R 20 , R 21 , R 23 , R 24 , R 25 , R 26 and R 27 Each instance of R is hydrogen. 2 , R 3 , R 15 , R 16 , R 28 and R 29Each instance of R is independently selected from the group consisting of hydrogen and C1-C5 alkyl. 2 , R 3 , R 15 , R 16 , R 28 and R 29 Each instance of is hydrogen.

[0044] In some embodiments, R of formula (III) 9 and R 22 Each instance of C1-C 10 alkyl or polyether. For example, R 9 or R 22 may be a polyether selected from polyethylene glycol and polypropylene glycol. The polyethylene glycol or polypropylene glycol may have a molecular weight of about 100 g / mol to about 1,000 g / mol, for example, about 400 g / mol to about 700 g / mol.

[0045] In some embodiments, R of formula (III) 31 , R 32 and R 33 Each instance of R is a bond. 31 , R 32 and R 33 Each instance of C1-C 10 In some embodiments, R 31 , R 32 and R 33 Each instance of each instance of is independently selected from phenyl. For example, phenyl is a group of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0046] In some embodiments, R of formula (III) 1 and R 30 is hydrogen. In some embodiments, R 1 and R 30 is a silyl. For example, the silyl can be a glycidyl ether silyl. In some embodiments, the silyl has the formula: [ka] where R 45 , R 46 and R 47 is hydrogen and C1-C 20 alkyl, e.g., C1-C5 alkyl; R 48 is selected from the group consisting of (divalent) alkyl, cycloalkyl, ether, and aryl. In some embodiments, R 48 is alkyl or ether. In some embodiments, silyl is [ka] or [ka] is.

[0047] In some embodiments, the Schiff base oligomer has formula (IV): [ka] wherein: R 9 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 28 and R29 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 33 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 41 Each instance of is independently -NH- or a bond; 40 each instance of is independently -NH- or -NH-NH-; R 42 Each instance of is independently -NH- or a bond; 43 each instance of is independently -NH- or -NH-NH-; each instance of z and t is an integer independently selected from the group consisting of 1 to 50, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 44 is a hydroxyl or a decarboxylated derivative thereof, or has the structure: [ka] wherein: R 1 is hydrogen or silyl, R 2 and R 3 are independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 31 is selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 50 is -NH- or a bond, and R 32 is -NH- or -NH-NH-, R 34 is -NH- or a bond, and R 35 is -NH- or -NH-NH-, x is an integer from 1 to 50, e.g., an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 30is hydrogen, silyl, or has the structure: [ka] wherein: R 9’ is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 44’ is a hydroxyl or its decarboxylated derivative.

[0048] In some embodiments of Formula (IV), R 28 or R 29 (or R 2 and R 3 Each instance of R is independently selected from the group consisting of hydrogen and C-C alkyl. 28 or R 29 (or R 2 and R 3 ) is hydrogen.

[0049] In some embodiments of Formula (IV), R 41 is -NH-, R 40 is -NH- and / or R 41 If is a bond, R 40 is -NH-NH-. In some embodiments, R 42 is -NH-, R 43 is -NH- and / or R 42 If is a bond, R 43 is -NH-NH-.

[0050] In some embodiments of Formula (IV), R 50 is -NH-, R 32 is -NH- and R 50 If is a bond, R 32 is -NH-NH-. In some embodiments, R 34 is -NH-, R 35 is -NH- and R 34 If is a bond, R 35is -NH-NH-.

[0051] In some embodiments of Formula (IV), R 9 (or R 9’ ) independently, C1-C 10 R is alkyl or aryl. 9 (or R 9’ ) is cyclohexyl C1-C 10 R can be cycloalkyl. 9 (or R 9’ ) can be aryl, which is phenyl. For example, phenyl is a group of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0052] In some embodiments of Formula (IV), R 33 (or R 31 ) is a bond. 33 (or R 31 ) are instances of C1-C 10 In some embodiments, R 33 (or R 31 Each instance of is independently selected from phenyl. For example, phenyl is a group of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0053] In some embodiments of Formula (IV), R 30 and R 1 is hydrogen. In some embodiments, R 30 and R 1 is a silyl. For example, the silyl can be a glycidyl ether silyl. In some embodiments, the silyl has the formula: [ka] where R 45 , R 46 and R 47 is hydrogen and C1-C 20 alkyl, e.g., C1-C5 alkyl; R 48 is selected from the group consisting of (divalent) alkyl, cycloalkyl, ether, and aryl. In some embodiments, R 48 is alkyl or ether. In some embodiments, silyl is [ka] or [ka] is.

[0054] In some embodiments, the Schiff base oligomer has formula (V): [ka] wherein: The wavy line is a line interrupting a single bond shown to indicate the point of attachment of the second wavy line to the oligomer represented by formula (V) (in other words, R 36 is R 14 (attached to the alpha carbon of R 2 , R 3 , R 15 , R 16 , R 28 and R 29 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 9 and R 22 each is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 31 , R 33 and R 51 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 34 , R 37 , R 38 , R 41 , R 42 and R 50 Each instance of is independently -NH- or a bond; 32 , R 35 , R 36 , R 39 , R 40 and R 43 each instance of is independently -NH- or -NH-NH-; each instance of x, y, and z is an integer independently selected from the group consisting of 1 to 50, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 1 and R 30 is independently selected from the group consisting of hydrogen and silyl.

[0055] In some embodiments, each of x, y, and z in formula (V) is the integer 1.

[0056] In some embodiments of Formula (V), R 2 , R 3 , R 15 , R 16 , R 28 and R 29 Each instance of R is independently selected from the group consisting of hydrogen and C1-C5 alkyl. 2 , R 3 , R 15 , R 16 , R 28 and R 29 Each instance of is hydrogen.

[0057] In some embodiments, R of formula (V) 34 , R 37 , R 38 , R 41 , R 42 and R 50 are each -NH-, then R 32 , R 35 , R 36 , R 39 , R 40 and R 43 are each -NH-. In some embodiments, R 34 , R 37 , R 38 , R 41 , R 42 and R 50 If is a bond, R 32 , R 35 , R 36 , R 39 , R 40 and R 43 are -NH-NH-, respectively.

[0058] In some embodiments, R of formula (V) 9 and R 22 Each instance of C1-C 10 R is alkyl or aryl. 9 and R 22 is cyclohexyl C1-C 10 R can be cycloalkyl. 9 and R 22 can be an aryl that is phenyl. For example, phenyl can be an aryl of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0059] In some embodiments, R of formula (II) 31 , R 33 and R 51 Each instance of R is a bond. 31 , R 33 and R 51 Each instance of C1-C 10 In some embodiments, R 31 , R 33 and R 51 Each instance of each instance of is independently selected from phenyl. For example, phenyl is a group of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0060] In some embodiments, R of formula (V) 1 and R 30 is hydrogen. In some embodiments, R 1 and R 30 is a silyl. For example, the silyl can be a glycidyl ether silyl. In some embodiments, the silyl has the formula: [ka] where R 45 , R 46 and R 47 is hydrogen and C1-C 20 alkyl, e.g., C1-C5 alkyl; R 48 is selected from the group consisting of (divalent) alkyl, cycloalkyl, ether, and aryl. In some embodiments, R 48 is alkyl or ether. In some embodiments, silyl is [ka] or [ka] is.

[0061] In some embodiments, the Schiff base oligomer has formula (VI): [ka] wherein: The wavy line is a line interrupting a single bond shown to indicate the point of attachment at the second wavy line of the oligomer represented by formula (VI) (in other words, the NH next to the wavy line is an R 14 (attached to the alpha carbon of R 9 and R 22 each is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 2 , R3 , R 15 , R 16 , R 28 and R 29 are each independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 31 , R 32 and R 33 each is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 1 and R 30 is independently selected from the group consisting of hydrogen and silyl.

[0062] In some embodiments of Formula (VI), R 2 , R 3 , R 15 , R 16 , R 28 and R 29 Each of R is independently selected from the group consisting of hydrogen and C1-C5 alkyl. 2 , R 3 , R 15 , R 16 , R 28 and R 29 Each of is hydrogen.

[0063] In some embodiments, R of formula (VI) 9 and R 22 Each instance of C1-C 10 R is alkyl or aryl. 9 and R 22 is cyclohexyl C1-C 10 R can be cycloalkyl. 9 and R 22 can be an aryl that is phenyl. For example, phenyl can be an aryl of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0064] In some embodiments, R of formula (VI) 31 , R 32 and R 33 Each instance of R is a bond. 31 , R 32 and R 33 Each instance of C1-C 10 In some embodiments, R 31 , R 32 and R 33 Each instance of each instance of is independently selected from phenyl. For example, phenyl is a group of the formula: [ka] or [ka] where R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 In some examples, R 60 , R 61 , R 62 and R 63 Each of is hydrogen.

[0065] In some embodiments, R of formula (VI) 1 and R 30 is hydrogen. In some embodiments, R 1 and R 30is a silyl. For example, the silyl can be a glycidyl ether silyl. In some embodiments, the silyl has the formula: [ka] where R 45 , R 46 and R 47 is hydrogen and C1-C 20 alkyl, e.g., C1-C5 alkyl; R 48 is selected from the group consisting of (divalent) alkyl, cycloalkyl, ether, and aryl. In some embodiments, R 48 is alkyl or ether. In some embodiments, silyl is [ka] or [ka] is.

[0066] metal The Schiff base oligomer may be dispersible in a solvent. The Schiff base oligomer may be a composition comprising (e.g., dispersed or ionically bound to) one or more metals. For example, the metal may be a cationic species of a transition metal.

[0067] The metal may be in the form of a cation or metal salt. For example, the metal may be selected from the group consisting of alkaline earth metals, transition metals, and rare earth metal salts, such as Zn, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Ce, Co, Y, Bi, Cd, Pb, Ag, Sb, Sn, Cu, Fe, Ni, Li, Ca, Sr, Mg, Zr, Nd, Ba, Sc, and any combination thereof. For example, the metal may be selected from the group consisting of Zn, La, Pr, Ce, Co, Y, Ca, Sr, Ba, Sc, and Zr. The metal may be selected from at least one of Zn, Pr, and Ce. The metal may be Zn. The metal may be Ce. The metal may be Pr. Some examples of salts that may be used are nitrates, chlorides, acetates, or any combination thereof.

[0068] It will be understood that the metal can have any suitable oxidation state. For example, the typical oxidation state of Zn is +2. The typical oxidation states of Pr are +2, +3, and / or +4. The typical oxidation states of Ce are +2, +3, and +4. It will be understood that various combinations and groups of the above metal salts can be used in the compositions of the present disclosure.

[0069] Corrosion prevention substrate Substrates that can be protected from corrosion by a Schiff base oligomer or composition thereof can be any suitable substrate, such as a metal substrate or a plastic substrate. Metal substrates can include any substrate material having at least a portion of its surface made of metal, e.g., a portion of its outer surface made of metal. Metal substrates can include any metal requiring protection from corrosion. Metal substrates can include metals or alloys selected from aluminum, e.g., aluminum alloys. Metal substrates can also include aluminum alloys, e.g., alloys of aluminum with one or more metals selected from the group consisting of copper, magnesium, manganese, silicon, tin, zinc, and combinations thereof. The aluminum alloy can also include copper. The metal substrate can also be a copper-containing alloy, such as a copper-containing aluminum alloy. The amount of copper in the alloy can be about 1% to about 20% by weight, about 1% to about 18% by weight, about 1% to about 10% by weight, or about 1% to about 6% by weight. The aluminum alloy can also be an aerospace alloy, e.g., AA2XXX and AA7XXX types. For example, the aluminum alloy may be an AA2024 type or an AA7075 type. The aluminum alloy may be an automotive alloy, such as an AA6XXX type. The aluminum alloy may be a marine alloy, such as an AA5XXX type.

[0070] composition The present disclosure also relates to compositions (e.g., for inhibiting corrosion) comprising (a) a Schiff base oligomer and (b) a metal (e.g., a metal salt) selected from a rare earth metal, an alkaline earth metal, a transition metal, or a combination thereof. The Schiff base oligomer can interact (e.g., chelate) with the metal. When a solvent (such as water) is included in a composition of the present disclosure, the Schiff base oligomer can dissociate (e.g., reversibly coordinate) from the metal. In embodiments where the composition is substantially free of solvent, the Schiff base oligomer and the metal (e.g., a metal salt) can be in the form of a coordination oligomer (e.g., a compound having an ionic bond between the Schiff base oligomer and the metal), although such coordination oligomers are still considered compositions for purposes of the present disclosure.

[0071] For example, the composition can include (a) at least one Schiff base oligomer and (b) at least one metal (e.g., a metal salt), where the metal is selected from the group consisting of Zn, La, Pr, Ce, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Co, Y, Ca, Sr, Ba, Sc, and Zr. For example, the at least one metal can be any one of Zn, Ce, Pr, or a combination thereof.

[0072] The composition can include (a) at least one Schiff base oligomer and (b) at least one metal (e.g., a metal salt), where the metal is selected from the group consisting of Zn, Pr, Ce, and combinations thereof.

[0073] The compositions of the present disclosure may further contain a solvent to improve the solubility / dispersibility of the Schiff base oligomer. The solvent may be water, a glycol, or a ketone. The glycol may include a glycol acetate, such as glycol ether acetate. The ketone may include acetone or pentanone. In some embodiments, the solvent is 1-methoxy-2-propanol acetate, 4-methyl-2-pentanone, or a combination thereof. The Schiff base oligomers of the present disclosure are highly polar. Therefore, solvents with high dipole characteristics are suitable solvents. Some examples of solvents with moderate evaporation rates can be used. For example, commercially available formulations may contain multiple solvents, such as four or five solvents, with different evaporation rates to allow for coalescence, drying, and solidification. Solvents that evaporate too quickly, such as MEK or acetone, may not be desirable because they do not allow time for surface wetting, coalescence, and blushing (water condensation).

[0074] The concentration of the Schiff base oligomer may be about 0.001% to about 20% by weight, for example, about 0.1% to about 10% by weight, for example, about 1% to about 5% by weight, or about 5% to about 10% by weight, which can provide solubility / dispersibility of the Schiff base oligomer.

[0075] In some embodiments, the molar ratio of metal (e.g., metal salt:Schiff base oligomer) in the composition is provided to include an excess of metal (e.g., metal salt) relative to the Schiff base oligomer due to the presence of multiple moieties on the Schiff base oligomer that can interact with the metal. For example, the molar ratio of metal salt:Schiff base oligomer in the composition can be greater than about 1:1, greater than about 1.1:1, greater than about 1.2:1, greater than about 1.3:1, greater than about 1.4:1, greater than about 1.5:1, greater than about 1.6:1, greater than about 1.7:1, greater than about 1.8:1, greater than about 1.9:1, greater than about 2:1, greater than about 3:1, greater than about 4:1, greater than about 5:1, greater than about 6:1, greater than about 7:1, greater than about 8:1, greater than about 9:1, or greater than about 10:1. The ratio of metal salt to Schiff base oligomer in the composition may be less than about 45:1, less than about 40:1, less than about 35:1, less than about 30:1, less than about 25:1, less than about 20:1, less than about 15:1, or less than about 10:1. The ratio of metal to corrosion inhibitor in the composition may be greater than about 1:1 to about 45:1, about 1.5:1 to about 40:1, about 2:1 to about 35:1, about 2.5:1 to about 30:1, about 3:1 to about 25:1, about 3.5:1 to about 20:1, about 4:1 to about 15:1, or about 5:1 to about 10:1. For example, the ratio of metal to corrosion inhibitor in the composition can be from about 1.1:1 to about 45:1, from about 1.2:1 to about 40:1, from about 1.3:1 to about 35:1, from about 1.4:1 to about 30:1, from about 1.5:1 to about 25:1, from about 1.6:1 to about 20:1, from about 1.7:1 to about 15:1, from about 1.8:1 to about 10:1, from about 1.9:1 to about 9:1, or from about 2:1 to about 8:1.

[0076] The corrosion inhibitor composition is suitable for use and application to a variety of substrates, such as metal substrates, and can be provided, for example, as a coating composition. The composition can include one or more other additives or corrosion inhibitors suitable for use with the intended substrate.

[0077] After the composition is deposited on a substrate, the solvent (if used) can be partially, substantially, or completely removed by any suitable curing process. For example, the coating composition can be applied to the substrate either in a wet state or in a "not fully cured" state that dries or cures over time, i.e., the solvent evaporates. The coating can be dried or cured at ambient temperature or by accelerated means, such as an ultraviolet curing system, to form a film or "cured" paint. The coating can also be applied in a semi-cured or fully cured state, such as an adhesive.

[0078] The composition may be a coating composition comprising a film-forming organic polymer. The coating composition may be a paint composition. The coating composition may comprise one or more resins, such as epoxy-based resins. The coating composition may be a paint composition, such as an epoxy resin-based paint composition.

[0079] The coating composition may be a powder coating composition, such as a powder coating composition suitable for use in powder coating a variety of metal substrates, including aluminum alloys or steels, as described herein.

[0080] The compositions of the present disclosure can include one or more additives, such as pigments, fillers, and extenders. Examples of suitable additives that can be combined with the corrosion inhibitors described herein include, for example, binders, solvents, pigments (including soluble or insoluble extenders, fillers, corrosion-inhibiting pigments, etc.), additives (e.g., curing agents, surfactants, dyes, amino acids, etc.), etc. It should be noted that some additives can also be properly considered pigments, and vice versa (e.g., matting agents). More specifically, these "additives" include, but are not limited to, glycine, arginine, methionine, and amino acid derivatives such as methionine sulfoxide, methyl sulfoxide, and iodide / iodate; gelatin and gelatin derivatives such as animal and fish gelatin derivatives; linear and cyclic dextrins such as alpha and beta cyclodextrin; triflic acid, triflate, acetate, talc, kaolin; organic ion exchange resins such as organic cation and anion exchange resins; organic ion exchange resins pre-exchanged or reacted with salts, oxides, and / or mixed oxides of rare earth materials; and / or metal sulfates such as sulfates of rare earth materials, magnesium sulfate, calcium sulfate (anhydrous and hydrated forms), strontium sulfate, barium sulfate, and the like, and combinations thereof.

[0081] The composition may also contain other additives such as rheology modifiers, fillers, reinforcing agents, heat or UV stabilizers, flame retardants, lubricants, surfactants, etc. The additives are typically present in an amount of less than about 10% based on the total weight of the composition after curing. Examples include: (a) rheology modifiers such as hydroxypropyl methylcellulose (e.g., Methocell 311, Dow), modified ureas (e.g., Byk 411, 410) and polyhydroxycarboxylic acid amides (e.g., Byk 405); (b) film-forming agents such as esters of dicarboxylic acids (e.g., Lusolvan FBH, BASF), glycol ethers (e.g., Dowanol, Dow), etc. (c) wetting agents such as fluorosurfactants (e.g., 3M Fluorad) and polyether-modified polydimethylsiloxanes (e.g., Byk 307, 333); (d) surfactants such as fatty acid derivatives (e.g., Bermadol SPS 2543, Akzo) and quaternary ammonium salts; (e) dispersants such as nonionic surfactants based on primary alcohols (e.g., Merpol 4481, Dupont) and alkylphenol-formaldehyde-bisulfide condensates (e.g., Clariants 1494); (f) Antifoaming agent (g) corrosion inhibitors such as phosphate esters (e.g., ADDAPT, Anticor C6), alkylammonium salts of (2-benzothiazolylthio)succinic acid (e.g., Irgacor 153 CIBA), triazine dithiols, etc. (h) stabilizers such as benzimidazole derivatives (e.g., Bayer, Preventol BCM, biocidal film protectant); (i) leveling agents such as fluorocarbon-modified polymers (e.g., EFKA 3777); (j) Pigments or dyes such as fluorescent agents (Royale Pigments and chemicals); (k) organic and inorganic dyes, such as fluorescein, and (l) Lewis acids such as lithium chloride, zinc chloride, strontium chloride, calcium chloride and aluminum chloride; (m) Suitable flame retardants to retard flame spread, heat release, and / or smoke generation, which may optionally include any of the following (or a combination thereof): Phosphorus derivatives such as molecules containing phosphate, polyphosphate, phosphite, phosphazine and phosphine functional groups, for example, melamine phosphate, dimelamine phosphate, melamine polyphosphate, ammonium phosphate, ammonium polyphosphate, pentaerythritol phosphate, melamine phosphite and triphenylphosphine. Melamine, melamine cyanurate, melamine phthalate, melamine phthalimide, melam cyanurate, melem cyanurate, melon cyanurate, hexamethylenetetraamine, imidazole, nitrogen-containing derivatives such as adenine, guanine, cytosine and thymine. · Molecules containing boric acid functional groups such as ammonium borate and zinc borate. Molecules containing two or more alcohol groups such as pentaerythritol, polyethylene glycol, polyglycols and carbohydrates, e.g. glucose, sucrose and starch. Molecules that endothermically release non-combustible decomposition gases, such as metal hydroxides, e.g. magnesium hydroxide and aluminum hydroxide. Expandable graphite.

[0082] Aspects The present disclosure provides, inter alia, the following aspects, each of which can be considered to optionally include any alternative aspects: Clause 1. Formula (IV): [ka] An oligomer represented by the formula: R 9 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 28 and R 29 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 33 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 41 Each instance of is independently -NH- or a bond; 40 each instance of is independently -NH- or -NH-NH-; R 42 Each instance of is independently -NH- or a bond; 43each instance of is independently -NH- or -NH-NH-; each instance of z and t is an integer independently selected from the group consisting of 1 to 50, e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 44 is a hydroxyl or a decarboxylated derivative thereof, or has the structure: [ka] wherein: R 1 is hydrogen or silyl, R 2 and R 3 are independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 31 is selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 50 is -NH- or a bond, and R 32 is -NH- or -NH-NH-, R 34 is -NH- or a bond, and R 35 is -NH- or -NH-NH-, x is an integer from 1 to 50, e.g., an integer selected from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10; R 30 is hydrogen, silyl, or has the structure: [ka] wherein: R 9’ is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 44’ is a hydroxyl or its decarboxylated derivative, oligomer. Article 2.R 28 or R 2910. The oligomer of clause 1, wherein each instance of is independently selected from the group consisting of hydrogen and C1-C5 alkyl. Article 3.R 28 or R 29 3. The oligomer of clause 1 or 2, wherein each instance of is hydrogen. Article 4.R 41 is -NH-, R 40 is -NH- and R 41 If is a bond, R 40 is -NH-NH-, R 42 is -NH-, R 43 is -NH- and R 42 If is a bond, R 43 The oligomer of any one of clauses 1 to 3, wherein is -NH-NH-. Article 5.R 9 Each instance of C1-C 10 5. The oligomer of any one of clauses 1 to 4, which is alkyl or aryl. Article 6.R 9 Each instance of independently has the formula: [ka] or [ka] wherein R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 6. The oligomer of any one of clauses 1 to 5, wherein the alkyl is independently selected from the group consisting of: Article 7.R 60 , R 61 , R 62 and R 63 The oligomer of any one of clauses 1 to 6, wherein each of is hydrogen. Article 8.R 9 The oligomer of any one of clauses 1 to 7, wherein each instance of is cycloalkyl. Article 9.R33 The oligomer of any one of clauses 1 to 8, wherein each instance of is a bond. Article 10.R 33 Each example is C1-C 10 10. The oligomer of any one of clauses 1 to 9, wherein: Article 11.R 33 Each instance of [ka] or [ka] wherein R 60 , R 61 , R 62 and R 63 is hydrogen and C1-C 10 11. The oligomer of any one of clauses 1 to 10, wherein: Article 12.R 60 , R 61 , R 62 and R 63 12. The oligomer of any one of clauses 1 to 11, wherein each of is hydrogen. Article 13.R 30 13. The oligomer of any one of clauses 1 to 12, wherein is hydrogen. Article 14.R 44 14. The oligomer of any one of clauses 1 to 13, wherein is hydroxyl. Article 15.R 30 15. The oligomer of any one of clauses 1 to 14, wherein is silyl. Clause 16. The oligomer of any one of clauses 1 to 15, wherein the silyl is a glycidyl ether silyl. Clause 17. Cyril uses the formula: [ka] where R 45 , R 46 and R 47 Each of the groups is hydrogen and C1-C20 alkyl; R 48 17. The oligomer of any one of clauses 1 to 16, wherein is selected from the group consisting of alkyl, cycloalkyl, ether and aryl. Article 18.R 45 , R 46 , and R 47 18. The oligomer of any one of clauses 1 to 17, wherein each of is hydrogen. Article 19.R 45 , R 46 , and R 47 19. The oligomer of any one of clauses 1 to 18, wherein each of is C1-C5 alkyl. Article 20.R 45 , R 46 , and R 47 20. The oligomer of any one of clauses 1 to 19, wherein each of is ethyl. Article 21.R 48 21. The oligomer of any one of clauses 1 to 20, wherein is an ether. Article 22.R 48 22. The oligomer of any one of clauses 1 to 21, wherein is an ether. Article 23. Cyril [ka] and [ka] 23. The oligomer according to any one of clauses 1 to 22, selected from the group consisting of:

[0083] Example Example 1 After synthesis of the bis-thiosemicarbazone dicarbonyl compound, oligomers were formed using polyethylene glycol diglycidyl ether or similar diglycidyl ethers. Water-soluble diglycidyl ethers of polyethylene glycol are commercially available in 20 kg quantities from Nagase America LLC (Nagase, 2020a, 2020b) and have an average of 4, 9, 13, or 22 EO (ethylene oxide) repeat units, equivalent to molecular weights of approximately 300, 480, 640, and 1000, respectively.

[0084] Example 2 Simple dialdehydes, such as methylglyoxal or isophthalaldehyde, can be reacted with two molecules of thiosemicarbazide to give bis-thiosemicarbazones by refluxing in ethanol. These have the ability to both bind to metal surfaces via the tertiary nitrogen atoms of the thiocarbonyl and Schiff bases, and to form polymers via the thiocarbamide groups by reacting with another carbonyl group or reactive chain-extending species such as diglycidyl ethers. The use of low-cost diketones has also been demonstrated, with 2,4-pentanedione (acetylacetone) or 2,5-hexanedione (acetonylacetone) similarly reacting to give bis-thiosemicarbazones with greater distances between binding sites.

[0085] Synthesis of monomeric Schiff bases Thiosemicarbazide (0.01 mol, 0.91 g) was added to a 250 cm 3 Ethanol (50 cm 3 ) and attached to an ice-cooled reflux condenser attached to a magnetic stirrer. 3 ) in salicylaldehyde (0.02 mol, 2.44 cm 3) was added dropwise. The reaction mixture was acidified with concentrated HCl and refluxed at room temperature with constant stirring for 2 hours. The reaction mixture was allowed to stand for 40 minutes. A pale yellow precipitate was obtained, which was purified by filtration and repeated washing with distilled water and diethyl ether. It was dried at 40°C for 8 hours to give the monomeric Schiff base, N,N'-bis(salicylidene)thiosemicarbazide Schiff base, in 72% yield.

[0086] Synthesis of Schiff base oligomers (STFB) 250cm equipped with a thermometer, condenser and magnetic stirrer 3 in a 50cm three-neck round-bottom flask 3 Monomeric Schiff base (0.01 mol, 2.99 gm) in DMF was dissolved in formaldehyde (0.02 mol, 1.5 cm 3 Schiff base oligomers were synthesized by adding 0.5 cm of 40% aqueous NaOH to the HCl solution in a molar ratio of (2:1). 3 was added to the reaction mixture. The temperature was maintained at 70±5° C. for 1 hour with continuous stirring. The progress of the reaction was monitored by TLC (thin layer chromatography). 3 Barbituric acid (0.01 mol, 1.28 gm) in DMF was added and stirred again at 100°C for approximately 2.5 hours until a red-yellow sticky compound was obtained. This was then precipitated in distilled water and washed several times with acetone and diethyl ether. After drying in an oven at 40°C for 5-7 hours, the Schiff base oligomer STFB was obtained in 70% yield.

[0087] Synthesis of coordination oligomers Coordination oligomers of [Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)] were prepared by using an equimolar ratio (1:1) of Schiff base ligand and metal(II) acetate. A typical procedure for the preparation of metal polychelates of manganese(II) was as follows: Schiff base oligomer (0.01 mol) was added to (20 cm 3) dissolved in DMF and heated at 60°C in a three-necked round-bottom flask fitted with an ice-cooled condenser. A solution of manganese(II) acetate tetrahydrate Mn(CHCOO)4H0 (0.01 mol, 2.45 gm) was added to 15 cm of the solution with constant stirring. 3 This was added to a hot, clear solution of Schiff base in DMF and refluxed for 7 hours. Stirring was continued until complete dissolution and a clear color change were achieved. Finally, a brown, viscous solution was obtained. This was then precipitated, filtered, and washed several times with distilled water and diethyl ether, yielding a brown precipitate. This was then oven-dried at 45°C for 5-6 hours to obtain the manganese polychelate [STFB-Mn(II)] in 81% yield.

[0088] Reaction 1 - Proof of Concept of Schiff Base Reaction Using ethanol as the solvent and concentrated HCl as the reaction catalyst, both ends of the thiosemicarbazide react with an aldehyde such as salicylaldehyde as shown below in 72% isolated yield. Scheme 1 [ka]

[0089] Reaction 2 As shown below, approximately 1.8 equivalents of a dialdehyde (or other dicarbonyl such as a keto-aldehyde or diketone) and 1 equivalent of thiosemicarbazide are used to make the oligomeric species. Scheme 2 [ka] Reaction 3 Scheme 3 [ka] Reaction 4 Scheme 4 [ka]

[0090] Formation of bis-thiosemicarbazone of terephthalaldehyde (1) A 250 mL three-neck round-bottom flask was charged with a solution of thiosemicarbazide (9.11 g, 0.100 mol) dissolved in 100 mL of ethanol. A PTFE stir bar was added, and the flask was placed in a flexible heating mantle on a magnetic stir plate. A reflux condenser was attached to the center neck. One side neck was fitted with an addition funnel containing a solution of terephthalaldehyde (6.57 g, 0.049 mol) in 50 mL of ethanol. The other side neck was fitted with a second addition funnel containing a solution of 1 mL of 12 N HCl (concentrated HCl) in 20 mL of ethanol. Scheme 5 [ka]

[0091] The solution of terephthalaldehyde was slowly added to the flask with stirring at room temperature over 30 minutes, followed by the solution of HCl. After the acid was added, the heating mantle was turned on and the mixture was refluxed for 2-3 hours. The heat was turned off and the mixture was allowed to slowly return to room temperature. The product precipitated as a yellow solid and was collected by filtration through a Buchner funnel. The product was washed with purified water (3 x 50 mL) and ethyl ether (1 x 50 mL) and dried overnight in a 100°F oven. 10 H 12 N6S2: Molecular weight 280.41. Yield = 13.74 product. By-products are 0.18 g excess thiosemicarbazide and 1.76 g water.

[0092] Reaction of (1) with diglycidyl ether or diisocyanate A solution of 5 grams of the polymer prepared in the previous section and 0.05 grams of the appropriate catalyst was dissolved in 25 mL of solvent. This solution was placed in a 100 mL three-neck round-bottom flask containing a PTFE stir bar and fitted with a reflux condenser, a dropping funnel, and a thermocouple. The flask was placed in a water bath and placed on a magnetically heated stir plate. The dropping funnel was charged with a solution of 0.9 equivalents of the desired chain extender (listed below) dissolved in 25 mL of the same solvent. This was added dropwise to the flask with stirring for 30 minutes, and the temperature was monitored. The temperature should rise as the two components combine. The temperature should be maintained below 100°C by appropriate means, such as adding ice to the water bath.

[0093] After 1 hour, all of the reactive chain extender should be consumed. Residual epoxy content can be determined by titration (ASTM D 1652) and residual isocyanate can be determined by titration (Dow, 2000).

[0094] [Table 1]

[0095] Formation of bis-thiosemicarbazone of pyruvaldehyde (2) A 250 mL three-neck round-bottom flask was charged with a solution of thiosemicarbazide (10.02 g, 0.110 mol) dissolved in 100 mL of ethanol. A PTFE stir bar was added, and the flask was placed in a soft heating mantle on a magnetic stir plate. A reflux condenser was attached to the center neck. One side neck was fitted with an addition funnel containing a solution of pyruvic aldehyde dimethyl acetal (5.78 g, 0.049 mol) in 50 mL of ethanol. This compound is also known as methylglyoxal dimethyl acetal. The other side neck was fitted with a second addition funnel containing a solution of 1 mL of 12 N HCl (concentrated HCl) in 20 mL of ethanol. Scheme 6 [ka]

[0096] [Table 2]

[0097] The thiosemicarbazide solution was heated to 50-60°C (just below reflux). To this, the pyruvic aldehyde dimethyl acetal solution was added with stirring at room temperature for 30-40 minutes, followed by the HCl solution. After the acid addition, the heating mantle and stirrer were turned off, and the mixture was allowed to slowly cool to room temperature for approximately 2 hours. If possible, place the reaction mixture in the refrigerator for 2 or 3 days to increase the crude yield. The product should precipitate as a yellow solid. The solid was collected in a Buchner funnel.

[0098] The crude product was recrystallized by dissolving it in a minimum amount of refluxing methanol in a beaker on a hot plate in a fume hood. An equal volume of distilled water was added, removed from the heat, and then allowed to cool. The product precipitated as off-white needles. Collect by filtration through a Buchner funnel. Dry in a 100°F oven overnight. C5H 10 N6S2: Molecular weight 218.29 Yield = 10.69 of product The by-products are 1.09 g of excess thiosemicarbazide, 3.13 g of methanol and 0.88 g of water. References: Petering, 1964.

[0099] Reaction of (2) with common diglycidyl ethers The reaction of two Schiff bases (SB) with three diglycidyl ethers is shown below. While the starting SB is a crystalline solid, the product is expected to be a viscous liquid more suitable for coating metal surfaces independently or as a component in a coating formulation. Other difunctional chain extenders can be considered. Scheme 7 [ka]

[0100] Schiff Base Oligomer and Epoxy Composition #1 A 500 cc reaction vessel equipped with a stirrer and a water-cooled condenser was charged with 179 grams (0.5 moles) of diglycidyl polyether of polypropylene glycol having an epoxy equivalent weight of 78.5 grams of Schiff base polymer, and 2.6 grams of powdered sodium hydroxide as catalyst. Cooling was used to moderate the reaction to 100-120°C during the first hour. At the end of this time, less than 1% of the diepoxide remained unreacted.

[0101] Schiff Base Oligomer and Epoxy Composition #2 2.47 grams of the Schiff base oligomer and epoxy composition or Schiff base oligomer composition was mixed with 0.87 grams (0.01 equivalents) of toluene diisocyanate (TDI) and 1.5 grams of dimethylformamide diluent. These compounds were mixed together, and the TDI was added last. Films were cast onto adhesive steel panels and baked at 300°F for several minutes to yield thermoset, transparent, orange coatings with high hardness.

[0102] material The following table lists materials that may be used as disclosed herein, including exemplary difunctional chain extenders that include diglycidyl ethers and diisocyanates.

[0103] [Table 3]

[0104] Schiff base oligomers with silyl end-capping A solution of 5 grams of the bis-thiosemicarbazone prepared in the previous section and 0.05 grams of the appropriate catalyst was dissolved in 25 mL of the desired solvent. This solution was placed in a 100 mL three-neck round-bottom flask containing a PTFE stir bar and fitted with a reflux condenser, a dropping funnel, and a thermocouple. The flask was placed in a water bath and placed on a magnetically heated stir plate. The dropping funnel was charged with a solution of 1.2 equivalents of the desired chain extender dissolved in 25 mL of the same solvent. This was added dropwise to the flask with stirring for 30 minutes, and the temperature was monitored. As the two components combined, the temperature should rise. The temperature was maintained below 100°C by appropriate means, such as adding ice to the water bath. After 1 hour, all of the reactive chain extender should be consumed. Residual epoxy content can be determined by titration (ASTM D1652), and residual isocyanate can be determined by titration (Dow, 2000).

[0105] The use of small amounts of trimethoxysilylpropyl glycidyl ether provided end groups that could react with metal surfaces via metal-O-Si bond formation. Scheme 8 [ka]

[0106] This type of structure has multiple modes of binding to the metal surface, including three bis-Schiff base groups, a secondary hydroxyl group, and by cleavage of the three ethoxysilyl groups by, for example, OH groups on the metal surface.

[0107] This silyl end-capping Schiff base oligomer can be dissolved in a suitable solvent at low solids to prepare a solution for dip or spray coating of metal parts. Drying can be accomplished by heating with an IR heat source, a hot air source, or some combination of the two.

[0108] chemical terms As used herein, wavy lines in chemical structures indicate the point of attachment between the depicted moiety and the remainder of the molecule.

[0109] As used herein, the term "composition" can include components of the composition (e.g., oligomer and metal and / or metal salt) and / or the reaction product of two or more components of the composition.

[0110] Unless otherwise stated / claimed, the groups / moieties of the Schiff base oligomers described herein are unsubstituted or substituted. The term "substituted" means that the group is substituted at any available position. Substitution can be, for example, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, aryl, heterocyclyl, heteroaryl, formyl, alkanoyl, cycloalkanoyl, aroyl, heteroaroyl, carboxyl, alkoxycarbonyl, cycloalkyloxycarbonyl, aryloxycarbonyl, heterocyclyloxycarbonyl, heteroaryloxycarbonyl, alkylaminocarbonyl, cycloalkylaminocarbonyl, arylaminocarbonyl, heterocyclylaminocarbonyl, heteroarylaminocarbonyl, cyano, alkoxy, cycloalkoxy, aryl ... The substituent may be one or more groups selected from oxy, heterocyclyloxy, heteroaryloxy, alkanoate, cycloalkanoate, arylate, heterocyclate, heteroarylate, alkylcarbonylamino, cycloalkylcarbonylamino, arylcarbonylamino, heterocyclylcarbonylamino, heteroarylcarbonylamino, nitro, hydroxyl, halo (-F, -Cl, -Br, -I), haloalkyl, haloaryl, haloheterocyclyl, haloheteroaryl, haloalkoxy, silylalkyl, alkenylsilylalkyl, alkynylsilylalkyl, or amino. In some embodiments, the substitution may be halo, alkyl, formyl, or amino. Optional substitutions may include salts of the group, such as carboxylate salts. It is understood that "substituted" may include other groups not specifically recited.

[0111] "Alkyl," whether used alone or in compound terms such as alkoxy, alkylthio, alkylamino, dialkylamino, or haloalkyl, refers to a straight or branched chain hydrocarbon ranging in size from 1 to about 10 carbon atoms or more. Thus, unless expressly limited to a smaller group, alkyl moieties include moieties ranging in size from 1 to about 6 carbon atoms or more, such as, for example, methyl, ethyl, n-propyl, iso-propyl, butyl, pentyl, hexyl, and higher isomers containing straight or branched chain hydrocarbons ranging in size from, for example, about 6 to about 10 carbon atoms or more.

[0112] "Cycloalkyl" refers to monocyclic or polycyclic ring systems of various sizes, e.g., from about 3 to about 10 carbon atoms, e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, or cycloheptyl. The term cycloalkyloxy refers to the same groups attached through an oxygen atom, such as cyclopentyloxy and cyclohexyloxy. The term cycloalkylthio refers to the same groups attached through a sulfur atom, such as cyclopentylthio and cyclohexylthio.

[0113] As understood, an aromatic group refers to a cyclic group having 4m+2 π electrons, where m is an integer equal to or greater than 1. As used herein, "aromatic" is used interchangeably with "aryl" to refer to an aromatic group, regardless of the valency of the aromatic group. Thus, aryl refers to monovalent aromatic groups, divalent aromatic groups, and higher polyvalent aromatic groups.

[0114] "Aryl," whether used alone or in compound terms such as arylalkyl, aryloxy, or arylthio, refers to (i) an optionally substituted monocyclic or polycyclic aromatic carbocyclic moiety, e.g., having from about 6 to about 60 carbon atoms, e.g., phenyl, naphthyl, or fluorenyl, or (ii) an optionally substituted partially saturated polycyclic carbocyclic aromatic ring system in which aryl and cycloalkyl or cycloalkenyl groups are fused together to form a ring structure such as a tetrahydronaphthyl, indenyl, indanyl, or fluorene ring.

[0115] Whether used alone or in compound terms such as heterocyclyloxy, "heterocyclyl" or "heterocyclic" refers to (i) an optionally substituted cycloalkyl or cycloalkenyl group, e.g., a cycloalkyl or cycloalkenyl group of about 3 to about 60 ring members which may contain one or more heteroatoms such as nitrogen, oxygen, or sulfur (e.g., pyrrolidinyl, morpholino, thiomorpholino, or fully or partially hydrogenated thienyl, furyl, pyrrolyl, thiazolyl, oxazolyl, etc.). (ii) an optionally substituted partially saturated polycyclic ring system in which an aryl (or heteroaryl) ring and a heterocyclic group are fused together to form a ring structure (examples include chromanyl, dihydrobenzofuryl, and indolinyl), or (iii) an optionally substituted fully or partially saturated polycyclic fused ring system having one or more bridges (examples include quinuclidinyl and dihydro-1,4-epoxynaphthyl).

[0116] A heteroaromatic group is an aromatic group or ring that contains one or more heteroatoms, such as N, O, S, Se, Si, or P. As used herein, "heteroaromatic" is used interchangeably with "heteroaryl," and heteroaryl groups refer to monovalent, divalent, and higher polyvalent aromatic groups that contain one or more heteroatoms. "Heteroaryl" is considered a non-limiting type of "heterocyclyl."

[0117] "Heteroaryl," whether used alone or in compound terms such as heteroaryloxy, refers to (i) an optionally substituted monocyclic or polycyclic aromatic organic moiety, e.g., about 1 to about 10 ring members, in which one or more of the ring members is an element other than carbon, e.g., nitrogen, oxygen, sulfur, or silicon, and the heteroatom interrupts the carbocyclic ring structure and has a sufficient number of delocalized π-electrons to provide aromaticity, provided the ring does not contain adjacent oxygen and / or sulfur atoms. Exemplary 6-membered heteroaryl groups are pyrazinyl, pyridazinyl, pyrazolyl, pyridyl, and pyrimidinyl. All positional isomers, e.g., 2-pyridyl, 3-pyridyl, and 4-pyridyl, are contemplated. Exemplary 5-membered heteroaryl rings are furyl, imidazolyl, oxazolyl, isoxazolyl, isothiazolyl, oxadiazolyl, pyrrolyl, 1,3,4 thiadiazolyl, thiazolyl, thienyl, triazolyl, and silole. All positional isomers are contemplated, e.g., 2-thienyl and 3-thienyl. Bicyclic groups are typically benzo-fused ring systems derived from the heteroaryl groups described above, e.g., benzofuryl, benzimidazolyl, benzthiazolyl, indolyl, indolizinyl, isoquinolyl, quinazolinyl, quinolyl, and benzothienyl, or (ii) optionally substituted partially saturated polycyclic heteroaryl ring systems in which heteroaryl and cycloalkyl or cycloalkenyl groups are fused together to form a ring structure such as a tetrahydroquinolyl or pyrindinyl ring.

[0118] "Hydroxyl" and "hydroxy" can be used interchangeably and refer to an --OH moiety.

[0119] "Alkoxy" and "alkoxyl" may be used interchangeably and refer to an -O-alkyl group, where alkyl is as defined above. Examples include methoxy, ethoxy, n-propoxy, isopropoxy, and the different butoxy, pentoxy, hexyloxy and higher isomers.

[0120] "Aryloxy" and "aryloxyl" can be used interchangeably and refer to an -O-aryl group, where the aryl group is as defined above. Examples include, but are not limited to, phenoxy and naphthoxy.

[0121] The compounds described herein may include salts, solvates, hydrates, isomers, tautomers, racemates, stereoisomers, enantiomers, or diastereoisomers of the compounds. For example, salts may include sodium, potassium, calcium, nitrate, phosphate, sulfate, chloride, or combinations thereof.

[0122] While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following appended claims.

Claims

1. Formula (IV): 【Chemical 1】 An oligomer represented by the formula: R 9 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 28 and R 29 each instance of is independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 33 each instance of is independently selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 41 Each instance of is independently —NH— or a bond; 40 each instance of is independently -NH- or -NH-NH-; R 42 Each instance of is independently —NH— or a bond; 43 each instance of is independently -NH- or -NH-NH-; each instance of z and t is an integer from 1 to 50; R 44 is a hydroxyl or has the structure: 【Chemistry 2】 wherein: R 1 is hydrogen or silyl, R 2 and R 3 are independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, and aryl; R 31 is selected from the group consisting of alkyl, cycloalkyl, aryl, heterocyclyl, and a bond; R 50 is -NH- or a bond, and R 32 is -NH- or -NH-NH-, R 34 is -NH- or a bond, and R 35 is -NH- or -NH-NH-, x is an integer from 1 to 50, R 30 is hydrogen, silyl, or has the structure: 【Chemistry 3】 wherein: R 9’ is selected from the group consisting of alkyl, cycloalkyl, aryl, heteroaryl, and ether; R 44’ is hydroxyl, However, when at least one terminal carboxyl group is present, the terminal carboxyl group may be decarboxylated. Oligomer.

2. R 28 or R 29 Each instance of 1 -C 5 alkyl, and optionally R 28 or R 29 2. The oligomer of claim 1, wherein each instance of is hydrogen.

3. R 41 When is -NH-, R 40 is -NH- and R 41 If is a bond, R 40 is -NH-NH-, R 42 When is -NH-, R 43 is -NH- and R 42 If is a bond, R 43 is -NH-NH-, 3. The oligomer according to claim 1 or 2.

4. R 9 Each instance of C 1 -C 10 alkyl or aryl, and / or optionally R 9 2. The oligomer of claim 1, wherein each instance of is cycloalkyl.

5. R 9 Each instance of independently has the formula: 【Chemistry 4】 or 【Chemistry 5】 wherein R 60 , R 61 , R 62 and R 63 is hydrogen and C 1 -C 10 2. The oligomer of claim 1, wherein each of the alkyl groups is independently selected from the group consisting of alkyl.

6. R 60 , R 61 , R 62 and R 63 The oligomer of claim 5 wherein each of is hydrogen.

7. R 33 2. The oligomer of claim 1, wherein each instance of is a bond.

8. R 33 Each instance of C 1 -C 10 alkyl, and / or optionally R 33 Each instance of 【Chemistry 6】 or 【Chemistry 7】 wherein R 60 , R 61 , R 62 and R 63 is hydrogen and C 1 -C 10 2. The oligomer of claim 1, wherein each of the groups is independently selected from alkyl.

9. R 60 , R 61 , R 62 and R 63 The oligomer of claim 8 wherein each of is hydrogen.

10. R 30 2. The oligomer of claim 1, wherein is hydrogen.

11. R 44 10. The oligomer of claim 1, wherein is hydroxyl.

12. R 30 2. The oligomer of claim 1, wherein is silyl.

13. The silyl is a glycidyl ether silyl, and / or the silyl is a silyl of the formula: 【Chemistry 8】 where R 45 , R 46 and R 47 Each of the 1 -C 20 alkyl; R 48 is selected from the group consisting of alkyl, cycloalkyl, ether and aryl.

14. R 45 , R 46 and R 47 is hydrogen or R 45 , R 46 and R 47 14. The oligomer of claim 13, wherein each of is ethyl.

15. R 48 14. The oligomer of claim 13, wherein is an ether.

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