Affiliation:
1. Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical Technology North Third Ring Road 15, Chaoyang Beijing 100029 China
2. State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Renmin Street 5625, Chaoyang Changchun 130022 China
3. Chimie ParisTech PSL University CNRS Institut de Recherche de Chimie Paris 11 rue Pierre et Marie Curie Paris 75005 France
Abstract
AbstractMetamaterials feature extraordinary physical properties that break the cognitive limitations of human beings on traditional materials. Auxetic materials and liquid crystal elastomers (LCEs) are representative of typical mechanical and thermal metamaterials. Their combination may introduce some unconventional and counterintuitive performances. Nevertheless, studies on LCEs with negative Poisson's ratio (v) are still rare. Herein, a liquid crystal vitrimer (Poly‐LCE) is developed that is a polydomain main‐chain LCE containing dynamic ester bonds. Its orientation process to monodomain (Mono‐LCE) is greatly simplified by transesterification reaction‐induced topological network rearrangement under mechanical alignment. By optimizing geometric parameters of re‐entrant (R) structures and orientation of liquid crystal units, all samples of R‐Poly‐LCE, R‐Mono‐LCE (//), and R‐Mono‐LCE (⊥) show negative Poisson's ratio (NPR) below 2% elongation (v = −0.22–0 for R‐Poly‐LCE, v = −0.12–0 for R‐Mono‐LCE (//) and v = −0.16–0 for R‐Mono‐LCE (⊥)). Interestingly, R‐Poly‐LCE presents v > 0 within 2%–10% axial elongation, while R‐Mono‐LCE (//) and R‐Mono‐LCE (⊥) exhibit v ≈ 0 under the same elongation. Materials with negative and zero Poisson's ratios are interesting in niche applications. This work develops a simple method to prepare these materials by liquid crystal vitrimers.
Funder
Changchun Institute of Applied Chemistry, Chinese Academy of Sciences
Beijing Municipal Natural Science Foundation