Polymer complexes stabilized through hydrogen bonds. Influence of “structure defects” on complex formation: Viscometry and fluorescence polarization measurements

Abstract

Abstract The structure of polymer complexes stabilized through hydrogen bonds can be much influenced by the presence of nonactive groups (structure defects) on the polymer chains. In this paper two very simple homopolymer/copolymer systems are studied: the homopolymer is a polybase, polyoxyethylene (PEO) or polyvinylpyrrolidone (PVP), and the copolymer a partially neutralized poly(acrylic acid) (PAA). The acrylate groups on PAA chain behave as structure defects. Viscometry provides information about macroscopic structure of polymer complex in solution while fluorescence polarization is especially adapted for the study of the local mobility of polymer chains. Two kinds of structure are found: the first one is compact and implies a low viscosity of the mixture, eventually precipitation occurs, the second one is a highly branched structure, close to a gel, which leads to a very high increase in viscosity. For instance, the viscosity of the mixture may be several hundred times higher than the sum of the viscosities of the two individual polymer solutions. Such mixtures are especially adapted to be used like thickening agents.