ASSOCIATION STRUCTURE OF TELECHELIC ASSOCIATIVE THICKENERS IN WATER

We have examined aqueous solutions of an associative thickener [AT] po lymer (poly(ethylene oxide), M(n) = 8200, total M(n) almost-equal-to 3 4 000, 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 magnit ude greater than that of classical surfactant micelles). We also estab lish that the clusters persist upon dilution of the sample and under r heological stress. We propose a new model to account for this behavior .