A NOVEL NONIONIC HYDROGEL FROM 2-METHYL-2-OXAZOLINE .2. SYNTHESIS OF NONIONIC HYDROGEL, LIPOGEL, AND AMPHIGEL BY COPOLYMERIZATION OF 2-OXAZOLINES AND A BISOXAZOLINE

As a novel method for the preparation of a hydrogel based on a polyoxazoline, the copolymerization of 2-methyl-2-oxazoline and 2,2’-tetramethylenebis(2-oxazoline) was carried out with methyl triflate initiator. The obtained gel was isolated almost quantitatively after Soxhlet extraction. The resulting hydrogel showed a high swelling degree both in water and in 5% aqueous sodium chloride. The water uptake was up to 45 multiples of the weight of the dry gel. 2-Oxazoline monomers with various 2-alkyl substituents (methyl, ethyl, n-propyl, n-butyl, and n-octyl) were also copolymerized with the above bisoxazoline to produce gels having a wide variety of swelling characteristics, i.e., from hydrogel to lipogel (organogel) depending on the substituents. The gels from 2-n-propyl- or higher alkyl-2-oxazoline showed the characteristic properties of lipogels and were swollen in less polar organic solvents such as toluene or 1,2- dichloroethane. The gel from 2-ethyl-2-oxazoline was a characteristic amphiphilic gel (amphigel), which was swollen both in water and in organic solvents. © 1990, American Chemical Society. All rights reserved.