Wang Zhongming, Xia Longgang, Huang Guanwen, Du Xinghao, Xu Binbin, Feng Chun
Shanghai Key Laboratory of Advanced Polymeric Materials, School of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, People's Republic of China.
Langmuir. 2025 Jul 15;41(27):18292-18304. doi: 10.1021/acs.langmuir.5c02351. Epub 2025 Jul 2.
Crystallization-driven self-assembly (CDSA) of π-conjugated homopolymers/oligomers has emerged as a versatile strategy to generate various nanostructures without an extra polymer corona layer. However, this field remains in its infancy, with rare reports concerning this topic. To get an in-depth understanding of how the structure of π-conjugated homopolymers/oligomers affects CDSA behavior, in this contribution, a series of oligo(-phenylenevinylene) derivatives (OPV, where the subscript represents the number of repeat units) with different chain lengths ( = 3, 4, or 5) and chain end groups of aldehyde (CHO) and cyano/carboxyl (CN/COOH) were synthesized. The influence of the chain length and structure of the chain end groups of OPV on CDSA behavior was examined in detail. It was found that the increase in the chain length of OPV would increase the stacking strength of OPV units for both CHO- and CN/COOH-terminated OPV. In addition, the introduction of more electron-deficient CN/COOH units would lead to a more pronounced electron pull-push effect, which not only resulted in the red shift of the UV/vis absorbance and fluorescence bands of OPV but also increased the stacking strength of OPV units as a consequence of the enhancement of charge transfer interactions. CHO-terminated OPV-CHO and OPV-CHO and CN/COOH-terminated OPV-COOH remained in unimolecularly dissolved states in -butanol at 25 °C. On the contrary, OPV-CHO formed ribbon-like micelles with widths in the range from ∼20 to ∼150 nm and lengths up to several micrometers, and OPV-COOH formed ribbon-like micelles with a width of ∼20 nm under the same conditions. Interestingly, tube-like micelles with a length of tens of micrometers could be formed for OPV-COOH. By virtue of acid-base interactions, amino-based porphyrins can be immobilized onto the surface of the micelles of OPV-COOH. This work demonstrates a vital role of the chemical structure of π-conjugated oligomers/polymers in determining CDSA behavior, which will be beneficial to extending CDSA toward the creation of various functional π-conjugated nanostructures.
π共轭均聚物/低聚物的结晶驱动自组装（CDSA）已成为一种通用策略，可用于生成各种纳米结构，而无需额外的聚合物冠层。然而，该领域仍处于起步阶段，关于这一主题的报道很少。为了深入了解π共轭均聚物/低聚物的结构如何影响CDSA行为，在本论文中，合成了一系列具有不同链长（n = 3、4或5）以及醛基（CHO）和氰基/羧基（CN/COOH）链端基的寡聚（对苯撑乙烯撑）衍生物（OPV，下标表示重复单元的数量）。详细研究了OPV链长和链端基结构对CDSA行为的影响。研究发现，对于CHO端基和CN/COOH端基的OPV，OPV链长的增加都会提高OPV单元的堆积强度。此外，引入更多缺电子的CN/COOH单元会导致更显著的电子推拉效应，这不仅导致OPV的紫外/可见吸收和荧光带发生红移，还由于电荷转移相互作用的增强而提高了OPV单元的堆积强度。CHO端基的OPV-CHO和OPV-CHO以及CN/COOH端基的OPV-COOH在25℃的正丁醇中保持单分子溶解状态。相反，OPV-CHO形成了宽度在约20至约150nm范围内、长度可达几微米的带状胶束，而OPV-COOH在相同条件下形成了宽度约为20nm的带状胶束。有趣的是，OPV-COOH可以形成长度为几十微米的管状胶束。借助酸碱相互作用，氨基卟啉可以固定在OPV-COOH胶束的表面。这项工作证明了π共轭低聚物/聚合物的化学结构在决定CDSA行为方面的关键作用，这将有利于将CDSA扩展到创建各种功能性π共轭纳米结构。
