New side chain cholesterol-functionalised aliphatic polycarbonate copolymer: synthesis and phase behaviour

ABSTRACT

A new side cholesterol-functionalised liquid crystal (LC) copolymer based on aliphatic polycarbonate backbone was synthesised. The chemical structures of the block copolymers obtained in this study were characterised with Fourier Transform Infrared Spectroscopy (FT-IR) and Proton Nuclear Magnetic Resonance (¹H NMR) spectra. Their thermal stability and phase behaviours were investigated with thermogravimetric analysis (TGA) measurements, differential scanning calorimetry, and polarising optical microscopy. The molecular organisation in the mesophase was studied by temperature-dependent X-ray diffraction (XRD). As a result, the block copolymer bearing side cholesteryl groups showed a glass transition at 15.8°C and a smectic A (SmA) to isotropic phase transition at 151.3°C on heating cycle. XRD indicated that the block LC copolymer showed an interdigitated molecular arrangement of the mesogenic units within the smectic layers. This partial bilayer structure was similar to the SmA phase formed by polar mesogens.

Graphical Abstract

KEYWORDS:

• Cholesterol
• polycarbonate
• synthesis
• phase behaviour
• liquid crystal

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (51503093), Science and Technology Bureau of Shenyang (F14-231-1-05), Fundamental Research Funds for the Central Universities (N130205001), Liaoning Provincial Key Laboratory of Functional Textile Materials, and Science and Technology Committee of Liaoning Province (201501116, 2016LD0112 and 210602342).