LIVING CATIONIC POLYMERIZATION OF STYRENE BY THE 1-PHENYLETHYL CHLORIDE TIN TETRACHLORIDE INITIATING SYSTEM IN THE PRESENCE OF TETRA-N-BUTYLAMMONIUM CHLORIDE

An initiating system, consisting of 1-phenylethyl chloride, tin tetrachloride, and tetra-n-butylammonium chloride [CH3CH(Ph)C1/SnCl4/nBu4NCl], led to living cationic polymerization of styrene in CH2Cl2 solvent at-15°C; typically, CH3CH(Ph)Cl/SnCl4/nBu4NCl=20/100/40 mM for 1.0 M of styrene. The living nature of the process was confirmed by an increase in the number-average molecular weight ( {Mathematical expression}) of the polymers in direct proportion to monomer conversion and its continuation on supplying a fresh feed of styrene after the polymerization; the observed {Mathematical expression} was close to the calculated value assuming that one molecule of CH3CH(Ph)Cl yields one living polymer. Throughout these reactions, the polymer's molecular weight distribution (MWD) stayed very narrow ( {Mathematical expression}), though slightly broadening after the second monomer addition. In the absence of nBu4NCl, the CH3CH(Ph)Cl/SnCl4 system yielded polystyrene with a bimodal MWD where the lower polymer fraction alone was apparently of a long lifetime. Styrene polymerization with the H2O/SnCl4 system was also examined, both with and without added nBu4NCl, and a long-lived propagating species was obtained in the presence of nBu4NCl. © 1990 Springer-Verlag.