Construction of micelles and hollow spheres <i>via</i> the self-assembly behavior of poly(styrene-<i>alt-p</i>HPMI) copolymers with poly(4-vinylpyridine) derivatives mediated by hydrogen bonding interactions.

Ma, Tzu-Ling; Du, Wei-Ting; Kuo, Shiao-Wei · Soft Matter · 2023

basic_science · Level V

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Abstract

This study describes the preparation of hydrogen bonding connected micelles, consisting of a poly(styrene-<i>alt</i>-(<i>para</i>-hydroxyphenylmaleimide)) [poly(S-<i>alt</i>-pHPMI)] core and a poly(4-vinylpyridine) (P4VP) derivative shell in a selective solvent. The aim was to modify hydrogen bonding interaction sites at the core/shell interface by synthesizing P4VP derivatives in three different sequences, namely, P4VP homopolymers, PS-<i>co</i>-P4VP random copolymers, and block copolymers. TEM images showed the successful self-assembly of poly(S-<i>alt</i>-pHPMI)/PS-<i>co</i>-P4VP inter-polymer complexes into spherical structures. To dissolve the core structures, 1,4-dibromobutane was used as a cross-linking agent to tighten the PS-<i>co</i>-P4VP shell. The morphologies, particle sizes, hydrogen bonding, cross-linking reaction, and core dissolution were confirmed by TEM, DLS, FTIR, and AFM analyses. Poly(S-<i>alt-p</i>HPMI)/PS<sub>41</sub>-<i>r</i>-P4VP<sub>59</sub> hydrogen bonding connected micelles, cross-linked micelles, and hollow spheres were larger and more irregular than poly(S-<i>alt-p</i>HPMI)/P4VP inter-polymer complexes due to the random copolymer architecture and the decrease in intermolecular hydrogen bonds. However, poly(S-<i>alt-p</i>HPMI)/PS<sub>68</sub>-<i>b</i>-P4VP<sub>32</sub> resulted in rod- or worm-like structures after core dissolution.