SYNTHESIS OF END-FUNCTIONALIZED POLYSTYRENES WITH ORGANOSILICON END-CAPPING REAGENTS VIA LIVING CATIONIC POLYMERIZATION

The end-functionalization of living polymers with bases (methanol, benzylamine, diethyl sodiomalonate, and sodium methoxide) and organosilicon compounds [X-Si(CH3)(3); X-: CH2=C(CH3)COO-, CH3COO-, CH2=CHCH2-, C6H5-] was investigated in the living cationic polymerization of styrene initiated with the 1-phenylethyl chloride/SnCl4/ nBu(4)NCl system in CH2Cl2 at -15 degrees C. The four bases and C(6)H(5)SiMe(3), independent of their structures, were apparently incapable of reacting with the living end and invariably led to polystyrenes with the omega-end chlorine [similar to similar to similar to CH2CH(Ph)Cl] originated from the initiating system. The number-average end-functionality (($) over bar F-n) of the chloride, determined by H-1-NMR, was close to unity (($) over bar F-n > 0.9). The presence of chlorine in the polymer was also confirmed by elemental analysis. In contrast, the quenching by the trimethylsilyl compounds with X = methacryloxy, acetoxy, and allyl gave omega-end-functionalized polystyrenes with the corresponding terminal groups (X) for which the ($) over bar F-n values were close to unity (($) over bar F-n > 0.9). The effects of the structure of silyl compounds on end-capping are also discussed. (C) 1994 John Wiley & Sons, Inc.