Zheng Xihuang, Ren Min, Wang Huayang, Wang Huiying, Geng Zhen, Xu Jiangping, Deng Renhua, Chen Senbin, Binder Wolfgang H, Zhu Jintao
Key Laboratory of Materials Chemistry for Energy Conversion and Storage, Ministry of Education (HUST), School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China.
Chair of Macromolecular Chemistry, Faculty of Natural Science II, (Chemistry, Physics and Mathematics), Martin Luther University Halle-Wittenberg, von-Danckelmann-Platz 4, Halle (Saale), D-06120, Germany.
Small. 2021 May;17(18):e2007570. doi: 10.1002/smll.202007570. Epub 2021 Mar 18.
Halogen-bond driven assembly, a world parallel to hydrogen-bond, has emerged as an attractive tool for constructing (macro)molecular arrangement. However, knowledge about halogen-bond mediated confined-assembly in emulsion droplets is limited so far. An I N bond mediated confined-assembly pathway to enable order-order phase transitions is reported here. Compared to hydrogen bonds, the distinct features of halogen bonds (e.g., higher directionality, hydrophobicity, favored in polar solvents), offers opportunities to achieve novel nanostructures and materials. Polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) AB diblock copolymer is chosen as halogen acceptor, while an iodotetrafluorophenoxy substituted C-type homopolymer, (poly(3-(2,3,5,6-tetrafluoro-4-iodophenoxy)propyl acrylate), PTFIPA) is designed as halogen donor, synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Formation of halogen bonding donor-acceptor pairs between the PTFIPA homopolymer and the P4VP segments presented in PS-b-P4VP, increase the volume of P4VP domains, in turn inducing an order-to-order morphology transition sequence: changing from spherical → cylindrical → lamellar → inverse cylindrical, by tuning the PTFIPA content and choice of surfactant. Subsequent selective swelling/deswelling of the P4VP domains give rise to further internal morphology transitions, creating tailored mesoporous microparticles, disassembled nanodiscs, and superaggregates. It is believed that these results will stimulate further examinations of halogen bonding interactions in emulsion droplets and many areas of application.
卤素键驱动的组装是一种与氢键平行的领域，已成为构建（大）分子排列的一种有吸引力的工具。然而，迄今为止，关于乳液滴中卤素键介导的受限组装的知识仍然有限。本文报道了一种通过N→I键介导的受限组装途径来实现有序-有序相变。与氢键相比，卤素键的独特特征（例如，更高的方向性、疏水性、在极性溶剂中更有利）为实现新型纳米结构和材料提供了机会。选择聚苯乙烯-b-聚（4-乙烯基吡啶）（PS-b-P4VP）AB二嵌段共聚物作为卤素受体，同时设计一种碘代四氟苯氧基取代的C型均聚物（聚（3-（2,3,5,6-四氟-4-碘苯氧基）丙基丙烯酸酯），PTFIPA）作为卤素供体，通过可逆加成-断裂链转移（RAFT）聚合合成。PTFIPA均聚物与PS-b-P4VP中存在的P4VP链段之间形成卤素键供体-受体对，增加了P4VP域的体积，进而诱导有序到有序的形态转变序列：通过调节PTFIPA含量和表面活性剂的选择，从球形→圆柱形→层状→反圆柱形。随后对P4VP域进行选择性溶胀/去溶胀会导致进一步的内部形态转变，从而产生定制的介孔微粒、拆解的纳米盘和超聚集体。据信，这些结果将激发对乳液滴中卤素键相互作用及其许多应用领域的进一步研究。
