Switchable Block Copolymer Surfactants for Preparation of Reversibly Coagulatable and Redispersible Poly(methyl methacrylate) Latexes

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• 作者：Qi Zhang ; Guoqiang Yu ; Wen-Jun Wang ; Haomiao Yuan ; Bo-Geng Li ; Shiping Zhu
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：February 26, 2013
• 年：2013
• 卷：46
• 期：4
• 页码：1261-1267
• 全文大小：331K
• 年卷期：v.46,no.4(February 26, 2013)
• ISSN：1520-5835

文摘

Poly(2-(dimethylamino)ethyl methacrylate)-block-poly(methyl methacrylate) (PDMAEMA-b-PMMA) has been used as a surfactant in the preparation of PMMA latexes that can be coagulated and redispersed reversibly. In this work, we investigated in detail the effects of the block copolymer composition on the coagulation/redispersion performance of the latexes. A series of well-defined PDMAEMA-b-PMMA samples that have 10鈥?0 DMAEMA units and 5鈥?5 MMA units were synthesized through a two-step solution RAFT polymerization process and were used as the surfactant in the emulsion polymerization of MMA. PMMA latexes obtained with surfactants having MMA weight fraction (F_MMA) < 58.5% were stable. The particle size of the resulting PMMA latexes decreased gradually with the increase of F_MMA. The latex particles initially coagulated with a small amount of caustic soda could be repeatedly redispersed into fresh water through CO₂ bubbling with ultrasonication and coagulated through N₂ bubbling with some heating. The coagulation/redispersion process was repeatable through the CO₂/N₂ bubbling. The latexes showed excellent redispersibility with the surfactants of F_MMA < 46%. With F_MMA > 46%, the latex particle sizes could increase over 20% after the coagulation/redispersion process.