Self-Assembly and Temperature-Driven Chirality Inversion of Cholesteryl-Based Block Copolymers
Krishnasamy, Velmurugan; Qu, Wentao; Chen, Changlong; Huo, Haohui; Ramanagul, Karthick; Gothandapani, Velraj; Mehl, Georg H.; Zhang, Qilu; Liu, Feng
Professor Georg Mehl G.H.Mehl@hull.ac.uk
Professor of Organic and Materials Chemistry
Block copolymers (BCPs), comprising a poly(methyl methacrylate) (PMMA) block and a poly(cholesteryloxyhexyl methacrylate) (PChMA) block, were synthesized via reversible addition–fragmentation chain transfer polymerization. The self-assembly of the liquid crystalline BCPs was characterized by differential scanning calorimetry, polarized optical microscopy, and synchrotron-based small/wide-angle X-ray scattering. The results indicate the formation of both tilted and nontilted chiral smectic (SmC* and SmA*) phases. A phase transition from the SmA* to SmC* phase on cooling was observed for BCPs but not for PChMA homopolymers. The layer spacing (5.00 ± 0.18 nm) between those can be controlled to maintain the number of ChMA units while varying the lengths of the PMMA block, thus introducing systematically the SmC* phase. Furthermore, BCPs with the short PMMA block showed inversion of chirality at specific temperatures; however, for PChMA attached with the long PMMA block, no chirality inversion was observed. This mode of chirality switching, investigated by circular dichroism, NMR, and theoretical studies, is associated with the methyl substituents in the backbone affecting the packing of the polymers. The basic rules, described here, have the potential to be implemented for the design of a wide range of functional materials, where helix–helix conversion is of use.
|Journal Article Type||Article|
|Publisher||American Chemical Society|
|Peer Reviewed||Peer Reviewed|
|APA6 Citation||Krishnasamy, V., Qu, W., Chen, C., Huo, H., Ramanagul, K., Gothandapani, V., …Liu, F. (in press). Self-Assembly and Temperature-Driven Chirality Inversion of Cholesteryl-Based Block Copolymers. Macromolecules, https://doi.org/10.1021/acs.macromol.9b02264|
|Keywords||Block copolymer; Cholesterol; Liquid crystals; Self-assembly; Chirality inversion|
This file is under embargo until May 22, 2021 due to copyright reasons.
Contact G.H.Mehl@hull.ac.uk to request a copy for personal use.
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