Structure of polymer complexes in water

Laboratoire Léon Brillouin (CEA-CNRS ) Saclay - 91191 Gif sur Yvette, France

Received: 3 August 1998
Accepted: 4 December 1998

Abstract

We have observed by SANS the structure of polymer complexes formed in water by the hydrogen bonding association of a polyacid (poly(methacrylic acid), PMA) and a polybase (poly(ethylene oxide), PEO). The PMA is perdeuterated and the contrast variation method enables us to measure separately the structure factor of each polymer in the complex and their cross structure factor as a function of the pH. As the neutralization ratio of the polyacid becomes larger than 10%, no complexation occurs and the conformation of each polymer in the blend solution is close to that of the same polymer alone in solution at the same concentration. On the opposite, for lower degrees of neutralization, the complexation changes both the global and local conformation of the PEO and PMA chains, which appear to be zipped together, adopting the same compact structure. The size of the aggregates and their apparent fractal dimension increase with complexation.