Formation of Hyperbranched Amphiphilic Terpolymers and Unimolecular Micelles in One-Pot Copolymerization

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• 作者：Xu Wang ; Lianwei Li ; Weidong He ; Chi Wu
• 刊名：Macromolecules
• 出版年：2015
• 出版时间：October 13, 2015
• 年：2015
• 卷：48
• 期：19
• 页码：7327-7334
• 全文大小：463K
• ISSN：1520-5835

文摘

Utilizing self-assembled structures made of small molecular surfactants or linear amphiphilic copolymers to encapsulate hydrophobic chemicals generally faces a dilution challenge due to their critical micelle concentrations. In this study, we designed a one-pot self-condensing vinyl terpolymerization of poly(ethylene glycol) methyl ether methacrylate (PEG) and methacrylic acid (MAA) in n-butyl acetate by using a vinyl-functionalized chain transfer agent (C₁₂-raft). In the presence of hydrophobic epoxiconazole (EP) as a model chemical that can complex with MAA, the resultant amphiphilic hyperbranched terpolymer chains can form unimolecular micelles with EP encapsulated inside. The effects of monomer composition and EP content on the stability of the resultant dispersions in both n-butyl acetate and redispersing water were studied by combining static and dynamic laser light scattering, transmission electron microscopy, and ultraviolet鈥搗isible spectroscopy. We found the optimal encapsulation and stabilization molar ratio of [MAA]:[EP] = 1.0:0.8. Under such optimal conditions, the resultant dispersions can be stabilized for months in n-butyl acetate, good for storage, and for hours after redispersion in a large amount of water, sufficiently long for the field applications. Note that the principle demonstrated here is readily applicable to the dispersion and stabilization of other hydrophobic active ingredients, not only agrochemicals but also drugs, with some properly chosen monomers.