Influence of flexible spacer length on self-organization behaviors and photophysical properties of hemiphasmidic liquid crystalline polymers containing cyanostilbene

Abstract

A series of hemiphasmidic luminescent liquid crystalline polymers, in which the hemiphasmidic mesogen containing cyanostilbene were linked to the polymethacrylate main-chains via flexible spacers with different lengths, named poly {(Z)-m-(4-(1-cyano-2-(3,4,5-tris(octyloxy)phenyl)vinyl)phenoxy)alkyl methacrylate} (donated as Pr-m, m = 2, 4, 6, 8, 10) were synthesized via free radical polymerization. The phase structures and photophysical properties of Pr-m were investigated in detail by a combination of techniques including differential scanning calorimetry (DSC), polarizing optical microscopy (POM), small-angle X-ray scattering (SAXS), UV–Vis absorption spectra (UV–Vis spectra), photoluminescence spectra (PL spectra) and particle size analyzer. The results revealed that the phase structures of Pr-m transformed from hexagonal columnar phase (m = 2, 4) to smectic A phase (m = 6, 8, 10) with the increasing of flexible spacer length. All of the polymers featured similar AIEE properties, however, the solid state quantum yields of Pr-m decreased with the increasing flexible spacer length, and the solid quantum yields of Pr-m decreased from 8.55 (Pr-2) to 3.71 (Pr-10) with the increasing flexible spacer length.