Nitrogen containing dispersant-viscosity improvers

A process comprising grafting onto (P) a hydrocarbon polymer selected from the group consisting of (1) a hydrogenated polymer of dienes, wherein the diene comprises a conjugated diene selected from the group consisting of isoprene, butadiene, and piperylene;

• (2) a hydrogenated copolymer of a conjugated diene with a vinyl substituted aromatic compound, wherein the vinyl substituted aromatic compound is a styrenic compound;
• (4) an olefin-diene copolymer wherein the olefin comprises alpha olefins and (5) a star polymer, said hydrocarbon polymer having {overscore (M)}n ranging from 20,000 to about 500,000, when the polymer is not a star polymer, and up to about GPC peak molecular weight of 4,000,000 when the polymer is a star polymer, from 1 to about 50 moles, per mole of polymer, of (M) at least one alpha-beta unsaturated carboxylic acid or functional derivative thereof to form a carboxylic group containing intermediate, then reacting said intermediate with (C) from about 0.5 to about 1.25 equivalents, per equivalent of carboxylic acid or functional derivative thereof, of a heterocycle precursor wherein the reaction with the heterocycle precursor is conducted at a temperature ranging from about 100° C. to about 200° C. for a sufficient time to convert at least about 50% of the carboxylic groups to heterocyclic groups.

The process of claim wherein from about 60% to about 80% of the heterocycle precursor is reacted with the hydrocarbyl substituted carboxylic acid or anhydride before reaction with the grafted polymer.