Amphiphilic polymethacrylates as crosslinked polymer precursors obtained by free-radical monomethacrylate/dimethacrylate copolymerizations

As an extension of our work on the elucidation of the mechanism and control of 3-dimensional network formation in the free-radical crosslinking polyme rization and copolymerization of multivinyl compounds with. the aim to mole cularly design vinyl-type network polymers, novel amphiphilic polymers were prepared as crosslinked polymer precursors. Thus, benzyl methacrylate, a n onpolar monomer, was copolymerized radically with 5 mol % of triicosaethyle ne glycol dimethacrylate [CH2=C(CH3)CO(OCH2CH2)(23)OCOC(CH3)=CH2], a polar monomer, in the presence of lauryl mercaptan as a chain transfer agent. The resulting prepolymers (i.e., vinyl-type network-polymer precursors or amph iphilic polymers) were characterized mainly by viscometry using t-butylbenz ene (t-BB) and a t-BB/MeOH (80/20) mixture as solvents. The viscosities in the t-BB/MeOH (80/20) mixture were quite high compared with those in t-BB a nd completely reversed concentration dependencies were observed in the solv ents. These are discussed by considering the difference in conformation and the shrinkage of polar, flexible polyoxyethylene units or the entanglement of nonpolar, rigid primary chains. (C) 2000 John Wiley & Sons, Inc.