双亲性无规光敏共聚物的疏水基元对其自组装胶束乳化性能的影响

Emulsifying Performance of Self-Assemblies Based on an Amphiphilic Random UV-Sensitive Copolymer:Effect of Hydrophobic Composition

设计合成了一系列具有不同化学组成的双亲性无规光敏共聚物,聚(7-对乙烯基苄氧基-4-甲基香豆素-r-丙烯酸)(P(VM-r-AA)),通过选择性溶剂法自组装获得纳米胶束,并将纳米胶束用作大分子颗粒乳化剂,研究其在甲苯-水界面的稳定性能。研究表明:聚合物疏水基元含量的增加使自组装胶束结构由溶胀的微凝胶状向刚性颗粒状转变;同时,胶束初始乳化效率增加,但油水界面吸附稳定性显著下降。此外,通过对疏水基元PVM的摩尔分数为12%的胶束进行辐照交联,并研究其在不同pH下的乳化性能,结果表明:胶束表面溶胀的双亲性链段对其乳化性能产生了重要的影响。未交联的胶束保持着良好的乳化性能;而交联的胶束形变能力变差、刚性增强,在碱性条件下,彻底失去乳化能力。

Amphiphilic random UV sensitive copolymers,poly（7-（4-vinylbenzyloxyl）-4-methylcoumarin-co- acrylic acid） P（VM-r-AA）, were synthesized with various hydrophobic unit compositions. These polymers self-assembled into nano micelles in selective-solvent, which were used as polymeric particulate emulsifiers to stabilise the toluene-water interface.Experimentally, the more hydrophobic units the polymer contains, the more rigid the self-assembly micelles are, subsequently, the worse stability the emulsion stabilised by micelles exhibits. It is concluded that swelling polymer segments or chains played an important role in the emulsifying performance of the self assembly micelles, which further confirmed by the distinct discrepancy in the emulsifying performance of the P（VM-r-AA） micelles with PVM molar fraction 12% between the photo-cross-linked and not. Under alkaline condition, the cross linked micelles cann’t stabilise at the toluene water interface due to the restriction of the swelling polymeric chains, while stable toluene-in-water emulsions are stabilised by the uncross linked micelles.