Hydrothermal contraction–dilation of polymer networks by reversible complexation with a complementary macromolecule

Abstract

Abstract A mechanochemical system which works by complexation between a poly(methacrylic acid) (PMAA) network and poly(ethylene glycol) (PEG) was studied. A PMAA membrane swollen with an aqueous PEG solution, to which a load 100 times the weight of the membrane was attached, contracts by over 90% of its length when heated from 10°C to 60°C. The work per contraction was 5 × 10 −3 cal/g of membrane. The temperature at which the mechanochemical system undergoes a specified contraction can be regulated by the PEG concentration of the swelling fluid. The sign of the temperature coefficient of the membrane dimension can be reversed by addition of a small amount of ethanol to the swelling solution of PEG. A simple method for calculating the stability constant and thermodynamic parameters for the complexation is outlined.