Conformational changes and swelling behavior of poly[(methacrylic acid)-co-(methyl methacrylate)] gel in solution of linear poly(ethylene glycol)

Abstract

The contraction of poly[(methacrylic acid)-co-(methyl methacrylate)] [P(MAA-co-MMA)] gel induced by complexation with linear poly(ethylene glycol) (PEG) is quite different from that of poly(acrylic acid) (PAA) or poly(methacrylic acid) (PMAA) gels. The effects of molecular weight and concentration of PEG, cross-linking density and composition of the gel, and the pH of the external solution on the conformational transitions of P(MAA-co-MMA) gels were investigated. A special feature of the conformational transitions for the P(MAA-co-MMA) gel/PEG system is the absence of a certain range of PEG concentrations where a reswelling of the collapsed gel is observed. The strong hydrophobicity of PMMA units will improve the PEG/network hydrophobic interactions and thereby stabilize the formed complex inside the gel network.