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Keywords:

  • B(C6F5)3;
  • cationic polymerization;
  • emulsion polymerization;
  • suspension and dispersion polymerization

Abstract

Summary: The cationic polymerization of styrene derivatives [p-methoxystyrene (pMOS), p-hydroxystyrene (pHS), styrene (St)] and cyclopentadiene (CPD) using B(C6F5)3-based initiating systems in aqueous media is reported, focusing specifically on the influence of various additives (surfactant, solvent) on the control of the polymerization rate and molar masses. 1-(4-Methoxyphenyl)ethanol (1)/B(C6F5)3 system induced living dispersion (in solvent/water mixture, without surfactant) cationic polymerize-tion of pMOS and pHS, affording polymers which Mns increased in direct proportion to monomer conversion (Mn ≤ 4500 g mol−1) and which exhibited rather narrow molecular weight distributions (Mw/Mn ≤ 1.5). Polymerization of St and CPD in suspension (in water without surfactant) proceeded uniquely through activation of the initiator followed by irreversible termination by water giving oligomers with Mn ≤ 2000 g mol−1 and Mw/Mn ≤ 2.0. Besides, pHS also polymerized in a living fashion under emulsion (in micellar aqueous solutions) conditions (Mn ≤ 4500 g mol−1; Mw/Mn ≤ 1.5) using either BRIJ®97 or hexa-decyltrimethylammonium bromide (CTAB) as surfactants, whereas conventional non-living cationic polymerization occurred with pMOS (using BRIJ®97 or CTAB as surfactants) and CPD (using dodecylbenzenesulfonic acid, DBSA).