writer：Zhen Geng, Zhongkai Cheng, Yutian Zhu, Wei Jiang
keywords：协同自组装, PS-b-PAA, PS-b-P4VP, 冠状层间相互作用, 囊泡, pH响应
source：期刊
specific source：The Journal of Physical Chemistry B, 2016, 120(24), 5527-5533
Issue time：2016年

摘要：研究了聚苯乙烯-b-聚丙烯酸（PS144-b-PAA22）与聚苯乙烯-b-聚4-乙烯基吡啶（PS144-b-P4VP33）两亲性两嵌段共聚物在DMF/H2O混合溶剂中的协同自组装。两种共聚物单独自组装时均形成小球形胶束（SSMs），但等摩尔混合后协同自组装形成囊泡。研究发现，囊泡的形成归因于PAA与P4VP链之间的复杂相互作用，包括未电离丙烯酸单元与吡啶单元之间的氢键，以及电离丙烯酸单元与质子化吡啶单元之间的静电吸引。由于PAA和P4VP链间的这些相互作用依赖pH值，可通过加入HCl或NaOH方便地调控协同自组装形貌。在高H+或OH-加入量下，冠状层间相互作用呈排斥性，共聚物混合物倾向于形成SSMs（碱性条件）或圆柱形胶束（酸性条件）；而在低H+或OH-加入量下，冠状层间相互作用为吸引性，体系倾向于聚集成囊泡。有趣的是，在高H+加入量和低OH-加入量条件下可获得相同形貌，这是由冠状层间相互作用随HCl或NaOH加入量的非单调变化所致。该研究表明，决定协同自组装形貌的是冠状层间相互作用，而非单纯的化学条件。

Abstract：The cooperative self-assembly of amphiphilic polystyrene-block-poly(acrylic acid) (PS144-b-PAA22) and polystyrene-block-poly(4-vinylpyridine) (PS144-b-P4VP33) diblock copolymers in DMF/H2O mixtures has been investigated. Both copolymers self-assemble into small spherical micelles (SSMs) if used individually. However, the equimolar mixture of these two copolymers cooperatively self-assembles into vesicles. It is found that the formation of vesicles is attributed to the complex interactions between PAA and P4VP chains, including the hydrogen bonds between un-ionized acrylic acid units and pyridine units as well as the electronic attractions between ionized acrylic acid units and protonated pyridine units. Since these interactions between PAA and P4VP chains depend on pH value, the cooperatively self-assembled morphology can be easily tuned by the addition of HCl or NaOH. At high addition of H+ or OH-, the intercorona interaction is repulsive and the copolymer mixture tends to form SSMs (basic condition) or cylindrical micelles (acidic condition), whereas it prefers to aggregate into vesicles at low addition of H+ or OH- because the intercorona interaction is attractive. Interestingly, the same morphology of the self-assembled aggregates can be obtained either at high H+ addition or at low OH- addition, which results from the nonmonotonic variation of the intercorona interaction along with the addition of HCl or NaOH. The current study implies that it is the intercorona interaction rather than the chemical condition that dominates the cooperatively self-assembled morphology.

论文链接：https://doi.org/10.1021/acs.jpcb.6b00273