Facile morphological control of fluorescent nano/microstructures via self-assembly and phase separation of trigonal azobenzenes showing aggregation-induced emission enhancement in polymer matrices
Facile morphological control of fluorescent nano/microstructures via self-assembly and phase separation of trigonal azobenzenes showing aggregation-induced emission enhancement in polymer matrices
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DOI：
10.1039/c5tc00462d
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发表时间：
2015-01-01
影响因子：
6.4
通讯作者：
Seki, Takahiro
中科院分区：
文献类型：
--
作者：
Han, Mina;Takeoka, Yukikazu;Seki, Takahiro
我们报道了一种简便温和的策略，通过自组装和相分离的三角偶氮苯生色团（3 N1）在聚合物基质[聚（甲基丙烯酸甲酯）（PMMA）和/或聚（4-氯苯乙烯）（PSCl）]中显示聚集诱导发射增强（AIEE）构建不同的荧光纳米/微米结构。高于玻璃化转变温度的热处理增强了聚合物链的大规模分子运动，这导致AIEE活性3 N1分子在受限的均聚物（分别为PMMA和PSC 1）基质中组装成荧光纳米棒和长纳米棒。引人注目的是，所制备的3 N1-PMMA-PSCl三元混合物表现出灿烂的树莓状形态。换句话说，具有微米级圆形突起的不平坦的岛状表面被红色荧光纳米球装饰。该结果可以解释为在快速溶剂蒸发期间不混溶的PMMA和PSC 1的表面定向相分离，这将有助于3 N1组分在不平坦表面上瞬时组装成纳米球。通过在玻璃化转变温度以上退火，从树莓状到珠状结构的独特形态转变可以通过以下方式容易地可视化：（i）3 N1分子固有地组装成红色荧光球形或1D聚集体，以及（ii）由于3 N1与PMMA或PSC 1之间的相容性差异而产生的选择性荧光标记。
We report a facile and mild strategy for constructing diverse fluorescent nano/microstructures via self-assembly and phase separation of trigonal azobenzene chromophores (3N1s) showing aggregation-induced emission enhancement (AIEE) in polymer matrices [poly(methyl methacrylate) (PMMA) and/or poly(4-chlorostyrene) (PSCl)]. Thermal treatment above the glass transition temperature enhances the large-scale molecular motions of the polymer chains, which causes AIEE-active 3N1 molecules to assemble into fluorescent nanorods and long nanosticks in the confined homopolymer (PMMA and PSCl, respectively) matrices. Strikingly, as-prepared 3N1-PMMA-PSCl ternary mixtures exhibit a splendid raspberry-like morphology. In other words, the uneven island-like surfaces with micrometer-scale round protuberances are decorated with red fluorescent nanospheres. This result can be interpreted as surface-directed phase separation of immiscible PMMA and PSCl during quick solvent evaporation, which would help the 3N1 components instantaneously assemble into nanospheres on uneven surfaces. By annealing above the glass transition temperature, a distinct morphological transformation from a raspberry-like to a bead-like structure could readily be visualized via (i) the inherent assembly of 3N1 molecules into red fluorescent spherical or 1D aggregates and (ii) the selective fluorescence marking due to the difference in compatibility between 3N1 and PMMA or PSCl.