Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China.
Langmuir. 2012 Jun 26;28(25):9211-22. doi: 10.1021/la301605a. Epub 2012 Jun 7.
Self-assembled polymeric micelles can be used as efficient particulate emulsifiers. To explore the relationship between the structure and the oil-water interfacial behavior of the micelle emulsifiers, a new type of amphiphilic random copolymer, poly{(styrene-alt-maleic acid)-co-[styrene-alt-(N-3,4-dihydroxyphenylethyl-maleamic acid)]} (SMA-Dopa), was synthesized, self-assembled into micelles, and used as emulsifiers. SMA-Dopa was synthesized via an aminolysis reaction between dopamine and commercial alternating copolymer poly(styrene-alt-maleic anhydride) (SMA). Dopamine moiety facilitated the self-assembly of the SMA-Dopa in selective-solvent into stable micelles, and increased the adsorption of the SMA-Dopa at the oil-water interface. Additionally, the structural transition of the self-assembled SMA-Dopa52 micelles in response to pH and salinity changes were confirmed by means of TEM, AFM, DLS, aqueous electrophoresis techniques, potentiometric titration, and pyrene fluorescence probe methods. Micelles shrunk with increasing salinity, and flocculation of the shrunken primary micelles occurred at salt concentration exceeding 0.1 M. The micelles swelled with increasing pH, and the disassociation of the SMA-Dopa52 micelles occurred at pH above approximately 6.5. The structure of the micelles plays a crucial role in the oil-water interfacial performance. Micelles with various structures were used as emulsifiers to adsorb at the styrene-water and toluene-water interfaces. The emulsifying characteristics demonstrated that self-assembled SMA-Dopa52 micelles with moderately swollen structure (at 2 < pH < 6) combine the advantages of the solid particulate emulsifiers and polymeric surfactants, possessing excellent emulsifying efficiency and good emulsion stability. Moreover, the emulsifying performance of the SMA-Dopa52 micelles could be enhanced by the addition of salt.
自组装聚合物胶束可用作高效的颗粒乳化剂。为了探索胶束乳化剂的结构与油水界面行为之间的关系，合成了一种新型两亲性无规共聚物聚{（苯乙烯-alt-马来酸）-co-[苯乙烯-alt-（N-3,4-二羟基苯乙基-马来酰胺酸）]}（SMA-Dopa），自组装成胶束，并用作乳化剂。SMA-Dopa 通过多巴胺与商业交替共聚物聚（苯乙烯-alt-马来酸酐）（SMA）之间的氨解反应合成。多巴胺部分促进了 SMA-Dopa 在选择性溶剂中的自组装成稳定的胶束，并增加了 SMA-Dopa 在油水界面上的吸附。此外，通过 TEM、AFM、DLS、水电泳技术、电位滴定和芘荧光探针方法证实了自组装 SMA-Dopa52 胶束对 pH 和盐度变化的结构转变。随着盐度的增加，胶束收缩，当盐浓度超过 0.1 M 时，收缩的初级胶束发生絮凝。随着 pH 的增加，胶束膨胀，当 pH 高于约 6.5 时，SMA-Dopa52 胶束发生解离。胶束的结构在油水界面性能中起着至关重要的作用。具有不同结构的胶束用作乳化剂，在苯乙烯-水和甲苯-水界面上吸附。乳化特性表明，具有适度肿胀结构（2 < pH < 6）的自组装 SMA-Dopa52 胶束结合了固体颗粒乳化剂和聚合物表面活性剂的优点，具有优异的乳化效率和良好的乳液稳定性。此外，通过添加盐可以增强 SMA-Dopa52 胶束的乳化性能。
