Nonionic hydrogels based on poly(methyl triethylene glycol vinyl ether)

Two types of nonionic hydrogels have been synthesized in the present study by cationic polymerization. The first type was prepared by precipitative co polymerization of methyl triethylene glycol vinyl ether (MTVE) and tetraeth ylene glycol divinyl ether (TDVE). Methyl tert-butyl ether (MTBE) was used as a polymerization medium, because it is a good solvent for the monomers b ut not a solvent for their copolymer. The swelling capacity of the copolyme rs was found to reach its maximum (10 g/g), when the content of TDVE used a s a crosslinker was 5 wt%. Another type was synthesized by cationic copolymerization of MTVE and vinyl oxyethyl methacrylate (VEM) followed by the radical crosslinking. The monom ers were first copolymerized in dichloromethane at -78 degreesC to afford a water-soluble copolymer in almost quantitative yield. Then the copolymers were crosslinked using ammonium persulfate as a radical initiator. The cros slinked products containing 0.3 wt% of VEM exhibited maximum swellability i n water (24 g/g). Both types of hydrogels were shown to be stable in the presence of an elect rolyte salt as well as over a wide pH range of aqueous media.