Surfactant-Free Polymerization Forming Switchable Latexes That Can Be Aggregated and Redispersed by CO2 Removal and Then Readdition
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- 作者：Xin Su ; Philip G. Jessop ; Michael F. Cunningham
- 刊名：Macromolecules
- 出版年：2012
- 出版时间：January 24, 2012
- 年：2012
- 卷：45
- 期：2
- 页码：666-670
- 全文大小：303K
- 年卷期：v.45,no.2(January 24, 2012)
- ISSN：1520-5835
文摘
Polystyrene latexes prepared using the bicarbonate salt of initiator 2,2鈥?azobis[2-(2-imidazolin-2-yl)propane] via surfactant-free emulsion polymerization can be aggregated using only argon and gentle heat and redispersed using carbon dioxide and sonication. The bicarbonate and hydrochloride salts of the initiator have similar thermal decomposition behavior, but only the bicarbonate salt of 2,2鈥?azobis[2-(2-imidazolin-2-yl)propane] can be switchable between ionic and nonionic forms by addition and removal of CO2. Measurements of particle size and zeta potential were used to study the aggregation and redispersion of the latexes. The latex is aggregated by heating and bubbling with argon to remove CO2 and convert the active cyclic amidinium groups to their neutral form. When treated with sonication and bubbling with CO2, the aggregated polystyrene latex can be redispersed successfully, as evidenced by restoration of the original latex particle size and zeta potential from the large aggregated polymer particles. This is the simplest method to date to prepare a redispersible latex stabilized by CO2.