Nitroxide-Mediated Controlled/Living Free-Radical Surfactant-Free Emulsion Polymerization of Methyl Methacrylate Using a Poly(methacrylic acid)-Based Macroalkoxyamine Initiator

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• 作者：Charlotte Dire ; Ste&#769 ; phanie Magnet ; Laurence Couvreur ; Bernadette Charleux
• 刊名：Macromolecules
• 出版年：2009
• 出版时间：January 13, 2009
• 年：2009
• 卷：42
• 期：1
• 页码：95-103
• 全文大小：616K
• 年卷期：v.42,no.1(January 13, 2009)
• ISSN：1520-5835

文摘

Water-soluble, SG1 nitroxide-capped poly(methacrylic acid-co-styrene) macroalkoxyamines with ∼10 mol % of styrene subunits were used as initiators in the surfactant-free, ab initio, batch, emulsion homopolymerization of methyl methacrylate and its copolymerization with a low percentage of styrene, in alkaline conditions at temperatures below 90 °C. The polymerizations were well-controlled, with a very high initiating efficiency, due to the high dissociation rate constant of the macroalkoxyamines. It led to the in situ formation of amphiphilic block copolymers that self-assembled into small particles with diameter below 100 nm, according to a polymerization-induced micellization process. The polymerization kinetics, the control over molar mass and molar distribution, and the colloidal characteristics of the so-formed block copolymer micelles were studied in detail. This work represents a breakthrough in controlled/living radical polymerization in aqueous emulsion with the development of new, very efficient macroinitiators used as the sole additive for initiation, stabilization, and chain-growth control. It is also the first development of nitroxide-mediated emulsion polymerization of methyl methacrylate performed at low temperature.