Synthesis of polydimethylsiloxane-block-polystyrene-block-polydimethylsiloxane via polysiloxane-based macroinitiator in supercritical CO2


Akgun M. , Deniz S. , Baran N., Uzun N. , Akgun N., Dincer S.

POLYMER INTERNATIONAL, vol.54, no.2, pp.374-380, 2005 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 54 Issue: 2
  • Publication Date: 2005
  • Doi Number: 10.1002/pi.1695
  • Title of Journal : POLYMER INTERNATIONAL
  • Page Numbers: pp.374-380

Abstract

Polydimethylsiloxane-block-polystyrene-block-polydimethylsiloxane (PDMS-b-PS-b-PDMS) was synthesized by the radical polymerization of styrene using a polydimethylsiloxane-based macroazoinitiator (PDMS MAI) in supercritical CO2. PDMS MAI was synthesized by reacting hydroxy-terminated PDMS and 4,4'-azobis(4-cyanopentanoyl chloride) (ACPC) having a thermodegradable azo-linkage at room temperature. The polymerization of styrene initiated by PDMS MAI was investigated in a batch system using supercritical CO2 as the reaction medium. PDMS MAI was found to behave as a polyazoinitiator for radical block copolymerization of styrene, but not as a surfactant. The response surface methodology was used to design the experiments. The parameters used were pressure, temperature, PDMS MAI concentration and reaction time. These parameters were investigated at three levels (-1, 0 and 1). The dependent variable was taken as the polymerization yield of styrene. PDMS MAI and PDMS-b-PS-b-PDMS copolymers obtained were characterized by proton nuclear magnetic resonance and infrared spectroscopy. The number- and weight-average molecular weights of block copolymers were determined by gel permeation chromatography. (C) 2004 Society of Chemical Industry.