Chinese Journal of Applied Chemistry ›› 2021, Vol. 38 ›› Issue (10): 1340-1352.DOI: 10.19894/j.issn.1000-0518.210343

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Controlled Synthesis and Photophysical Properties of Liquid Crystalline Diblock Copolymers with Side⁃Chain Discotic Triphylene and Calamitic Azobenzene Mesogens

Zhao-Yong ZHANG1‡, Qian LI1‡, Da-Lin WANG1, Jiang-Lin FANG2, Dong-Zhong CHEN1()   

  1. 1Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education,Department of Polymer Science and Engineering,School of Chemistry and Chemical Engineering,Nanjing University,Nanjing 210023,China
    2Center of Modern Analysis,Nanjing University,Nanjing 210093,China
  • Received:2021-07-16 Accepted:2021-08-31 Published:2021-10-01 Online:2021-10-15
  • Contact: Dong-Zhong CHEN
  • About
  • Supported by:
    National Natural Science Foundation of China(21875098)


A series of disk-rod hybrid diblock copolymers based on side-chain discotic triphenylene (TP) and calamitic azobenzene (Azo) mesogens with different length and ratio of the two block segments were well prepared via copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) click reaction. The reactive precursor blocks were synthesized through atom transfer radical polymerization (ATRP) or reversible addition-fragmentation chain transfer (RAFT) polymerization of Azo methacrylate and TP acrylate monomers using specially designed chain transfer agent and initiator with different functional groups. The structure, molecular mass and liquid crystalline phase behaviors of the thus obtained disk-rod diblock copolymers were characterized by 1H nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and polarization optical microscopy (POM). The hybrid diblock copolymer of P(TP640-b-P(Azo)10 with a shorter azobenzene block segment, mainly exhibits the thermal transition temperature and phase behavior of the dominant TP-based discotic liquid crystalline polymer (LCP). While the copolymers of P(TP610-b-P(Azo)40 and P(TP640-b-P(Azo)40 with a longer azobenzene block segment, reflect more of the phase behavior and photoresponse properties of the Azo-based side-chain LCP. Small-angle /wide-angle X-ray scattering (SAXS/WAXS) analysis confirms that the diblock copolymer films with a longer Azo-based segment are in a layered structure especially after annealing, the Azo mesogens are arranged in a flat lying orientation in parallel with the quartz substrate induced by the planar oriented TP mesogens, which significantly reduce the light absorbance of the UV-Vis spectra, then the light absorbance increases obviously after irradiation with 365 nm ultraviolet and then visible light, where P(TP640-b-P(Azo)40 with the longer TP-based block shows a particularly prominent increment. The study on the unique photophysical properties and specific photoresponse behaviors of such disk-rod hybrid diblock copolymer films can help to deepen the understanding of their interactions and are expected to provide guidance for the design and synthesis of novel photoresponsive materials.

Key words: Disk-rod hybrid diblock copolymers, Controlled radical polymerization, Click reaction, Photoresponse

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