Temperature- and pH-responsive behaviour of poly(2-(2-methoxyethoxy)ethyl methacrylate-co-N,N-dimethylaminoethyl methacrylate) hydrogels

Hydrogels with pH/temperature responsiveness and high water uptake have been synthesized by the free radical polymerization of 2-(2-methoxyethoxy)ethyl methacrylate (MEO(2)MA) with N N-dimethylaminoethyl methacrylate (DMAEMA) in a low proportion The amphiphilic character of the biocompatible MEO(2)MA provides thermo-sensitivity at low temperature On the other hand DMAEMA units incorporate ionisable amino groups and hydrophobic moieties leading by themselves to a dual pH and thermo-sensitive system Therefore the combination of both monomers yields an interesting system with tuneable pH/temperature responsiveness and swelling capacity which depends on composition and ionic strength Thus the volume transition temperature (VTT) is suppressed at low pH due to the basic character of DMAEMA However at basic pH where amino groups are not charged lower swelling capacities and narrow thermal volume transitions were obtained At neutral pH higher modulation of both the swelling achieved and VTT was observed (C) 2010 Elsevier Ltd All rights reserved