Synthesis of new polymethyloxazoline hydrogels by the macroinitiator method

New polymethyloxazoline hydrogels are synthesized by the cationic ring-opening copolymerization of 2-methyl-2-oxazoline and 2,2'-tetramethylenebis(2-oxazoline), using random copolymers of chloromethylstyrene and methyl methacrylate, or of chloromethylstyrene and styrene as macroinitiators. The synthesis is carried out in benzonitrile at 110degreesC in the presence of potassium iodide, which activates the chloromethyl group as initiating functionality. In general, the hydrogels are obtained very rapidly, with a yield of between 42 and 95 wt.-%. Besides the possibility of introducing heterogeneity into the hydrogel structure by forming rigid hydrophobic domains. The hydrogel structures were characterized by high-resolution magic angle spinning NMR spectroscopy, and their solvent absorption capacity was determined by swelling experiments in solvents of different polarity. The hydrogels showed maximal swelling degree of 18 g of water and 40 g of methanol, respectively, per gram of the hydrogel.