BACKGROUND

Lubricating motor oils intended for use in internal combustion engines are typically formulated with a variety of additives that are intended to aid in the reduction of corrosion, deposit formation, wear, etc. Ashless dispersants are a type of additive. The role of dispersants in lubricating oils is to regulate viscosity increases and prevent the formation of sludge, varnish, and other deposits, which occur due to the formation and presence of soot and other carbonaceous impurities that originate from the incomplete oxidation of fuel and that enter the base oil from the combustion chamber under normal operation of the engine. Thus, improved dispersants offer the potential to improve the performance of existing lubricating motor oils.

Likewise, it is well known that liquid fuel contains components that can degrade during engine operation and form deposits. These deposits can lead to incomplete combustion of the fuel resulting in higher emission and poorer fuel economy. Fuel additives, such as detergents, can be included in in liquid fuels to help control or minimize deposit formation. As the dynamics and mechanics of an engine continual advance, the requirements of the fuel must evolve to keep up with these engine advancements. For example, modern engines have injector systems that have smaller tolerances and operate at higher pressure to enhance fuel spray to the compression or combustion chamber. Deposit prevention and deposit reduction in these new engines has become critical to optimal operation. Advancements in fuel additive technology, such as improved detergents, are needed to keep pace with these engine advancements. Therefore, there is also need for improved detergents that can provide acceptable performance in liquid fuels and promote optimal operation of today's engines.

SUMMARY

Provided herein are polyimide compounds that include two or more cyclic imide moieties. By incorporating a plurality of cyclic imide moieties, the compounds can function as high potency dispersants. For example, in certain cases, the compounds can be used to reduce or prevent soot-induced thickening in heavy duty diesel engine oils.

For example, provided are polyimide compound defined by Formula I below


where A, individually for each occurrence, represents a cyclic diimide moiety represented by the structure below


where B represents a cyclic moiety (e.g., where B comprises an aryl group) substituted with a first cyclic imide group and a second cyclic imide group; Y, individually for each occurrence, represents a bivalent linking group; L, individually for each occurrence, is absent or represents a cyclic imide group; R, individually for each occurrence, represents a polymeric tail; and n is an integer from 1 to 20 (e.g., an integer from 1-6). In certain embodiments, n can be 1.

The bivalent linking group Y can be, for example, an alkylene, heteroalkylene, cycloalkylene, heterocycloalkylene, arylene, heteroarylene, alkylarylene, alkylheteroarylene, polyalkyleneoxy, or polyalkenylamino group. In some cases, Y can comprise from 2 to 30 carbon atoms (e.g., from 6 to 30 carbon atoms, or from 6 to 12)

The polymeric tail R can be, for example, a polyolefin group, a polyetheramine group; a polyalkenylamine group; a polyalkyleneoxy group, or a combination thereof. The polymeric tail can have a molecular weight of at least 500 Da. In some cases, R can be a hydrophobic moiety. In certain embodiments, R can comprise a polyolefin group terminated by an initiator residue (e.g., a polyisobutylene group terminated by an initiator residue).

In some embodiments, the compound can be a dispersant for use in lubricating oils, and R can have a molecular weight of from 1,000 Da to 2,500 Da. In other embodiments, the compound can be an additive for use in a hydrocarbon fuel, and R can have a molecular weight of less than 1,000 Da (e.g., from 100 Da to less than 1,000 Da).

In some embodiments, the first cyclic imide group and the second cyclic imide group can each comprise a five-membered cyclic imide ring. For example, A can be chosen from one of the following


where X is absent, or represents


polyalkyleneoxy, or polyalkenylamino; R1represents, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl, or wherein permissible, two adjacent R1groups, together with the atoms to which they are attached, form a 5-8 membered substituted or unsubstituted aromatic or non-aromatic ring; R2and R3represent, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl; Ar represents an aryl group; and m is an integer from 1 to 12.

In other embodiments, the first cyclic imide group and the second cyclic imide group can each comprise a six-membered cyclic imide ring. For example, A can be chosen from one of the following


where X is absent, or represents


polyalkyleneoxy, or polyalkenylamino; R1represents, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl, or wherein permissible, two adjacent R1groups, together with the atoms to which they are attached, form a 5-8 membered substituted or unsubstituted aromatic or non-aromatic ring; R2and R3represent, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl; Ar represents an aryl group; and m is an integer from 1 to 12.

In some embodiments, L can be absent. For example, in some cases, the polyimide compound can be defined by Formula IA below
Rx—Ra—Y—A-Yn—Ra—RxFormula IA
where A and n are as defined above with respect to Formula I, Rxis an initiator residue; and Rais a polyolefin group (e.g., Racomprises a polyisobutylene group).

In other embodiments, L can be present. For example, L can be, in all occurrences, a five-membered cyclic imide ring. In some of these cases, the polyimide compound can be defined by Formula IB below


where A, Y, and n are as defined above with respect to Formula I, Rxis an initiator residue; and Rais a polyolefin group (e.g., Racomprises a polyisobutylene group).

Also provided are methods of preparing the polyimide compounds described herein. For example, methods for preparing a polyimide compounds can comprise (a) providing a polymeric tail precursor comprising a terminal anhydride moiety (e.g., polyisobutenyl succinic anhydride (PIBSA)); and (b) condensing the polymeric tail precursor with a bivalent linker and a tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof to form the polyimide compound.

The bivalent linker can be a compound defined by the formula
H2N—Y—NH2
where Y is chosen from alkylene, heteroalkylene, cycloalkylene, heterocycloalkylene, arylene, heteroarylene, alkylarylene, alkylheteroarylene, polyalkyleneoxy, or polyalkenylamino.

In some embodiments, step (b) can comprise condensing the polymeric tail precursor with a bivalent linker and a cyclic dianhydride. The cyclic dianhydride can, in some cases, be chosen from one of the following


where X is absent, or represents


polyalkyleneoxy, or polyalkenylamino; R1represents, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl, or wherein permissible, two adjacent R1groups, together with the atoms to which they are attached, form a 5-8 membered substituted or unsubstituted aromatic or non-aromatic ring; R2and R3represent, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl; Ar represents an aryl group; and m is an integer from 1 to 12.

In some embodiments, step (b) can comprise combining the polymeric tail precursor, the bivalent linker, and the tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof to form a reaction mixture, and heating the reaction mixture to a temperature of at least 100° C. (e.g., a temperature of from 120° C. to 200° C.). Optionally, step (b) can comprise removing water from the reaction mixture to drive formation of the polyimide compound.

Also provided herein are methods for preparing a polyimide compound, the method comprising (a) providing a polymeric tail precursor comprising a terminal amine moiety (e.g., polyisobutylene amine (PIBA)); and (b) condensing the polymeric tail precursor with a tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof to form the polyimide compound.

In some embodiments, step (b) can comprise condensing the polymeric tail precursor with a cyclic dianhydride. The cyclic dianhydride can, in some cases, be chosen from one of the following


where X is absent, or represents


polyalkyleneoxy, or polyalkenylamino; R1represents, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl, or wherein permissible, two adjacent R1groups, together with the atoms to which they are attached, form a 5-8 membered substituted or unsubstituted aromatic or non-aromatic ring; R2and R3represent, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl; Ar represents an aryl group; and m is an integer from 1 to 12.

In some embodiments, step (b) can comprise condensing the polymeric tail precursor and the tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof with a bivalent linker. The bivalent linker can be a compound defined by the formula
H2N—Y—NH2
where Y is chosen from alkylene, heteroalkylene, cycloalkylene, heterocycloalkylene, arylene, heteroarylene, alkylarylene, alkylheteroarylene, polyalkyleneoxy, or polyalkenylamino.

In some embodiments, step (b) can comprise combining the polymeric tail precursor, the tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof, and the bivalent linker, when present to form a reaction mixture, and heating the reaction mixture to a temperature of at least 100° C. (e.g., a temperature of from 120° C. to 200° C.). Optionally, step (b) can comprise removing water from the reaction mixture to drive formation of the polyimide compound.

Also provided are methods for preparing a polyimide compound that comprise (a) generating a quasiliving polyolefin in a reversible deactivation-type living polymerization; (b) adding to the reversible deactivation-type living polymerization of step (a) a quenching agent to generate a quenched precursor; (c) reacting the quenched precursor to form an amine-capped polymeric tail precursor; and (d) condensing the amine-capped polymeric tail precursor with a tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof to form the polyimide compound.

Step (a) can comprise combining a Lewis acid and a monomer (e.g., isobutylene) with an initiator in the presence of an electron donor, common ion salt, common ion salt precursor, or combination thereof. In some cases, step (b) is performed after high conversion of the monomer has occurred.

Step (d) can comprise condensing the amine-capped polymeric tail precursor with a cyclic dianhydride. The cyclic dianhydride can, in some cases, be chosen from one of the following


where X is absent, or represents


polyalkyleneoxy, or polyalkenylamino; R1represents, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl, or wherein permissible, two adjacent R1groups, together with the atoms to which they are attached, form a 5-8 membered substituted or unsubstituted aromatic or non-aromatic ring; R2and R3represent, independently for each occurrence, H, halogen, alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, alkoxy, aryl, heteroaryl, alkylaryl, or alkylheteroaryl; Ar represents an aryl group; and m is an integer from 1 to 12.

In some embodiments, step (d) can comprise condensing the amine-capped polymeric tail precursor and the tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof with a bivalent linker. The bivalent linker can be a compound defined by the formula
H2N—Y—NH2
where Y is chosen from alkylene, heteroalkylene, cycloalkylene, heterocycloalkylene, arylene, heteroarylene, alkylarylene, alkylheteroarylene, polyalkyleneoxy, or polyalkenylamino.

In some embodiments, step (d) can comprise combining the amine-capped polymeric tail precursor, the tetracarboxylate, an ester thereof, an acid halide thereof, or a cyclic dianhydride thereof, and the bivalent linker, when present to form a reaction mixture, and heating the reaction mixture to a temperature of at least 100° C. (e.g., a temperature of from 120° C. to 200° C.). Optionally, step (d) can comprise removing water from the reaction mixture to drive formation of the polyimide compound.

Also provided herein are polyimide compounds prepared by the methods described herein.

