Preparation of stable poly(methacrylic acid)-b-polystyrene emulsion by emulsifier-free emulsion iodine transfer polymerization (emulsion ITP) with self-assembly nucleation

Publication date: 10 February 2017
Source:Polymer, Volume 110
Author(s): S. Sue-eng, T. Boonchuwong, P. Chaiyasat, M. Okubo, A. Chaiyasat
Emulsifier-free emulsion iodine transfer polymerization (emulsion ITP) of styrene with self-assembly nucleation was successfully carried out with some living features for the first time as follows. Firstly, poly(methacrylic acid) (PMAA; degree of polymerization, 37)-iodide (PMAA37-I) as a macro chain transfer agent was synthesized by solution reversible chain transfer catalyzed polymerization (solution RTCP) with 2,2′-azobis(4-methoxy-2,4-dimethylvaleronitrile) as an initiator, iodoform as a chain transfer agent and germanium iodide as a catalyst in dioxane at 40 °C. A dioxane solution of PMAA37-I and styrene were added stepwisely under stirring into an aqueous solution (pH∼9), and then emulsion ITP was initiated by adding 4,4′-azobis(4-cyanopentanoic acid) at 60 °C with stirring at 500 rpm. Stable polystyrene emulsion was obtained without coagulation. At 100% conversion, the number-average diameter was 223 nm. Number-average molecular weight (Mn) increased linearly with conversion, which were well closed to theoretical Mn and molecular weight distribution at 100% conversion was comparatively narrow (Mw/Mn∼2.1).

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