Synthesis and liquid crystalline behavior of side chain liquid crystalline polymers containing triphenylene discotic mesogens with different length flexible spacers

Abstract

A series of side chain liquid crystalline polymers (SCLCPs) containing triphenylene (Tp) units in the side chains, denoted as PMTS (without spacer) and PMTnS (n = 2, 3, 4, 6, which is the number of the methylene units between the main chain and Tp moieties in the side chains), with different lengths of spacers were synthesized through conventional free radical polymerization. The chemical structures of the monomers were confirmed by 1 H/ 13 C-NMR, and the phase behaviors were examined by differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (1D and 2D WAXD). The molecular characterization of the polymers was performed with 1 H-NMR, gel permeation chromatography (GPC) and thermogravimetric analysis (TGA). The phase behaviors of the polymers have been investigated by a combination of techniques including DSC, POM, 1D and 2D WAXD. The results showed that the length of spacer has significant effects on the LC phase behavior of polymers. For PMTS and PMT2S, they displayed the columnar phase developed by the Tp moieties and the main chain as a whole due to the strong coupling effect of the Tp moieties and the main chain. For the PMT3S, PMT4S and PMT6S, they formed the symmetry hexagonal columnar (Φ H ) phase owing to the decoupling effect. All of these indicated that the "decoupling effect" or "coupling effect" depended on the length of spacers, leading to the different LC phase formation mechanism.

Synthesis and characteristics of novel azo-based diblock copolymers and their self-assembly behavior via solvents and thermal annealing

“…This photoinduced orientation allows systems possessing azo-chromophore to be employed as photoswitches that could rapidly and reversibly control the material properties. Besides, the photoinduced orientation of azo groups in LC DBC is much more stable than other materials (21,22). Therefore, the azobenzene-containing DBC is believed to be a material that exhibits optical storage properties (23).…”

Influence of main chain on the phase behaviors of side‐chain liquid‐crystalline polymers with triphenylene mesogens of long alkyl tail substituents

“…With increase in spacer length and temperature, the polymers exhibited interesting phase behaviors. Recently, our group studied the effect of spacer length and alkyl tail length on the phase behaviors of Tp‐based SCLCPs . By changing the spacer length and tail length, the phase behaviors and phase structures of Tp‐based SCLCPs were studied elaborately.…”

Effects of rigid cores and flexible tails on the phase behaviors of polynorbornene-based mesogen-jacketed liquid crystalline polymers

“…Liquid crystalline polymers (LCPs) are important functional polymers with ordered structures, [1][2][3][4][5] and they are useful in information technology, 6,7 medical applications, 8 and materials science. [9][10][11] Their properties are not only strongly influenced by the chemical structures of the polymers themselves, but also deeply dependent on the self-assembled physical structures of the polymer chains.…”