Biomacrocyclic side-chain liquid crystalline polymers bearing cholesterol mesogens: facile synthesis and topological effect study?

Polymer Chemistry Pub Date: 2015-08-13 DOI: 10.1039/C5PY01003A

Abstract

Herein we describe the rational design and facile synthesis of biomacrocyclic side-chain liquid crystalline polymers bearing cholesterol mesogens with three different length methylene spacers (m = 2, 6, 11) via the combination of reversible addition–fragmentation chain transfer (RAFT) polymerization with Cu(I)-catalyzed azide–alkyne cycloaddition (CuAAC) “click” chemistry. The successful cyclization was confirmed by comprehensive characterization including size-exclusion chromatography (SEC), triple detection size-exclusion chromatography (TD-SEC), Fourier transform infrared (FT-IR) and 1H NMR spectra. Subsequently, the liquid crystalline (LC) phase behaviors of the linear and cyclic polymers were investigated systematically. Both linear and cyclic polymers form the smectic phase and exhibit a similar layer periodicity. However, the cyclic ones exhibit a slightly lower mesophase transition temperature, enthalpy, entropy and smaller textures compared with their linear counterparts. Meanwhile, the smectic C (SmC) phase is preferable in cyclic polymers with a long methylene spacer (m = 11) compared with that in the linear one.

Graphical abstract: Biomacrocyclic side-chain liquid crystalline polymers bearing cholesterol mesogens: facile synthesis and topological effect study
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