AMPHIPHILIC NETWORKS - SYNTHESIS AND CHARACTERIZATION OF AND DRUG RELEASE FROM POLY(2-HYDROXYETHYL METHACRYLATE)-1-POLYISOBUTYLENE

Amphiphilic networks comprising poly(2-hydroxyethyl methacrylate) (PHEMA) linked (1) by polyisobutylene (PIB) segments have been synthesized by radical copolymerization of 2-(trimethylsiloxy)ethyl methacrylate (TMSEMA) with methacrylate-telechelic PIB (MA-PIB-MA) followed by acid catalyzed removal of the trimethylsilyl groups. Conditions have been optimized for the synthesis of two series of PHEMA-1-PIB networks of various compositions. DSC traces exhibit a high and a low temperature T(g) (i.e., from 98 to 111-degrees-C and from -61 to -54-degrees-C, respectively) which indicates microphase separation into PHEMA and PIB domains. The amphiphilic and co-continuous nature of PHEMA-1-PIB networks was demonstrated by swelling both in n-heptane and water. The dry networks are transparent tough products; after swelling with water or n-heptane the swollen gels still exhibit satisfactory properties for diverse manipulation. Drug delivery systems were prepared by loading the networks with theophylline. Release studies indicate sustained drug delivery with anomalous diffusion kinetics.