Spontaneous gelation of poly(oligo-oxyethylene methacrylate)

Abstract

The spontaneous gelation of poly(oligo-oxyethylene methacrylate) was studied. When the solvent of the polymer solution was removed by freeze drying or evaporation under atmosphere, spontaneous gelation occurred. This gelation is caused by the radical generation and chain transfer reaction, which is evidenced by the prevention of gelation during freeze drying and evaporation under atmosphere with adding radical inhibitor into the polymer solution. The soluble residue of the crosslinked gel formed during freeze drying was found to be poly(ethylene glycol) which is the side chain of the polymer. This fact indicates that the cleavage of the side chain accompanies the gelation. The possible mechanism of the gelation is proposed with the idea that induced stress by solvent removal would cause the cleavage of the side chain and the generated radical is transferred to the other chain resulting in gelation.