Group-Transfer Polymerization of tert-Butyl Methacrylate and [3-(Methacryloxy)propyl]pentamethyldisiloxane: Synthesis and Characterization of Homopolymers and Random and Block Copolymers
journal contributionposted on 12.09.1996, 00:00 by Allen H. Gabor, Christopher K. Ober
A synthetic approach for preparing block copolymers consisting of both a [3-(methacryloxy)propyl]pentamethyldisiloxane (SiMA) block and tert-butyl methacrylate (t-BMA) block using group-transfer polymerization (GTP) was developed. The SiMA polymerizes slowly with oxyanion catalysis but at reasonable rates using bifluoride catalysis. A model reaction eliminated a possible explanation for the slow rate of polymerization of SiMA with oxyanion catalyzed GTP. For high conversion of t-BMA to be achieved, additional bifluoride catalyst had to be added to the reactor after the t-BMA addition. Often, especially at −44 °C, after the polymerization stalled, additional conversion of the t-BMA did not occur until a critical concentration of bifluoride catalyst was established. After this level was reached, the polymerization of t-BMA occurred quickly and to high conversion.