Abstract: The invention relates to 5-oxo-3-pyrrolidinecarboxylic acid derivatives having the structural formula ##STR1## wherein X is selected from the group of ##STR2## R.sub.2 and R.sub.3 are each H or CH.sub.3, and R.sub.1 is H or a hydrocarbon radical having from 1 to 20 carbon atoms, which derivative compounds are suitable as monomers which can be homopolymerized or copolymerized to yield high molecular weight materials having many useful properties and applications, among which is their ability to form complexes with water insoluble molecules which are normally not complexible with similar type polymers.

Abstract: What is described herein are polymerizable pyrrolidonyl 4,5-unsubstituted oxazoline monomers, homopolymers thereof, and copolymers with other monomers. A preferred polymerizable monomer compound is 2-(1-methyl-2-pyrrolidon-4-yl)-2-oxazoline. The polymers herein have excellent hydrotropic properties thus increasing the water solubility of organic compounds previously considered as water insoluble, and exhibit complexation with water soluble cosolutes.