Computational and experimental studies on the micellar morphology and emission mechanisms of AIE and H-bonding fluorescent composites

Guangying Zhou; Xiaomeng Cheng; Jian Yang; Yanyan Zhu; Hongping Li

doi:10.1039/d2ra07900c

Computational and experimental studies on the micellar morphology and emission mechanisms of AIE and H-bonding fluorescent composites

RSC Adv. 2023 Feb 6;13(7):4612-4622. doi: 10.1039/d2ra07900c. eCollection 2023 Jan 31.

Authors

Guangying Zhou¹, Xiaomeng Cheng^{2

3}, Jian Yang¹, Yanyan Zhu¹, Hongping Li¹

Affiliations

¹ Green Catalysis Center, College of Chemistry, Zhengzhou University Zhengzhou Henan 450001 China lihongping@zzu.edu.cn zhuyan@zzu.edu.cn.
² Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Colloid and Interface and Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences Beijing 100190 P. R. China.
³ School of Chemistry and Chemical Engineering, University of Chinese Academy of Sciences Beijing 100049 China.

Abstract

In this work, we use density functional theory (DFT) calculated competitive hydrogen bonds and dissipative particle dynamics (DPD) simulated micellar structural information to uncover the CO₂-expanded liquid (CXL)-aided self-assembled structure and emission mechanisms of the self-assembled fluorescent composites (SAFCs). Herein, the SAFCs are formed through the self assembly between diblock copolymer polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) blend and the dye molecule 4-(9-(2-(4-hydroxyphenyl)ethynyl)-7,10-diphenylfluoranthen-8-yl)phenol (4) in CO₂-expanded toluene at 313.2 K and varied pressures. Firstly, from DPD simulation, we have demonstrated that the addition of CO₂ to toluene favors both the expansion of the solvophobic P4VP phase and contraction of solvophilic PS chains, which facilitates the continuous morphological transitions of SAFCs from spherical micelles (3.0 MPa) through wormlike plus spherical micelles (4.0-4.8 MPa) to large vesicles (6.0-6.5 MPa) with pressure rise. Secondly, the DFT calculated bonding energies and IR spectra of the competitive hydrogen bonds help us to clarify the major type of hydrogen bonds determining the fluorescence (FL) performance of the SAFCs. Furthermore, we have revealed the SAFC emission mechanism via the pressure-tunable changes in the aggregation degrees and amount of hydrogen bonds involving 4 and P4VP chains. This work provides a good understanding for the morphology-property control of the self-assembled polymer composites in both microscopic and mesoscopic scales.