ASSOCIATION STRUCTURE OF TELECHELIC ASSOCIATIVE THICKENERS IN WATER

We have examined aqueous solutions of an associative thickener [AT] polymer (poly(ethylene oxide), M(n) = 8200, total M(n) almost-equal-to 34 000, with C16H33O- end groups) by a variety of techniques, including fluorescence and fluorescence decay measurements in conjunction with pyrene derivatives as fluorescent probes. These establish that ca. 20 AT end groups associate to form a hydrophobic cluster, and that these clusters have a very high microviscosity (more than an order of magnitude greater than that of classical surfactant micelles). We also establish that the clusters persist upon dilution of the sample and under rheological stress. We propose a new model to account for this behavior.