Silicon-terminated telechelic oligomers by ADMET chemistry: Synthesis and copolymerization

Methoxydimethylsilane and chlorodimethylsilane-terminated telechelic polyoc tenomer oligomers (POCT) have been prepared by acyclic diene metathesis (AD MET) chemistry using Grubbs' ruthenium Ru(Cl-2)(CH=Ph)(PCy3)(2) [Ru] or Sch rock's molybdenum Mo(=CH-CMe2Ph)(N-2,6-C6H3-i-Pr-2)(OCMe(CF3)(2))(2) [Mo] c atalysts. These macromolecules have been characterized by FTIR, H-1-, C-13- , and Si-29-NMR spectroscopy. The molecular weight distributions of these p olymers have been determined by GPC and vapor pressure osmometry (VPO). The number-average molecular weight (M-n) values of the telechelomers are dict ated by the initial ratio of the monomer to the chain limiter. The termini of these oligomers (M-n = 2000) can undergo condensation reaction with hydr oxy-terminated poly(dimethyl siloxane) (PDMS) macromonomer (M-n = 3300) [HO -Si(CH3)(2)-O-(-Si(CH3)(2)O-)(x) -Si(CH3)(3)], producing an ABA-type block copolymer, as follows: (CH3)(3)SiO-[-Si(CH3)(2)O-](x)-[-CH=CH-(CH2)(6)-](y) -[-OSi(CH3)(2-]x)-OSi(CH3)(3). The block copolymers were characterized by H -1- and C-13-NMR spectroscopy, VPO, and GPC, as well as elemental analysis, and were determined by VPO to have a M-n of 8600. (C) 1999 John Wiley & So ns, Inc.