title: Artificial muscles based on liquid crystal elastomers.
abstract: This paper presents our results on liquid crystal (LC) elastomers as artificial muscle, based on the ideas proposed by de Gennes. In the theoretical model, the material consists of a repeated series of main-chain nematic LC polymer blocks, N, and conventional rubber blocks, R, based on the lamellar phase of a triblock copolymer RNR. The motor for the contraction is the reversible macromolecular shape change of the chain, from stretched to spherical, that occurs at the nematic-to-isotropic phase transition in the main-chain nematic LC polymers. We first developed a new kind of muscle-like material based on a network of side-on nematic LC homopolymers. Side-on LC polymers were used instead of main-chain LC polymers for synthetic reasons. The first example of these materials was thermo-responsive, with a typical contraction of around 35-45% and a generated force of around 210 kPa. Subsequently, a photo-responsive material was developed, with a fast photochemically induced contraction of around 20%, triggered by UV light. We then succeeded in preparing a thermo-responsive artificial muscle, RNR, with lamellar structure, using a side-on nematic LC polymer as N block.Micrometre-sized artificial muscles were also prepared. This paper illustrates the bottom-up design of stimuli-responsive materials, in which the overall material response reflects the individual macromolecular response, using LC polymer as building block.
authors.affiliation: Institut Curie, CNRS UMR168, 26 Rue d'Ulm, 75248 Paris Cedex 05, France. min-hui.li@curie.fr
authors.forename: Min-Hui
authors.initials: MH
authors.lastname: Li
authors.forename: Patrick
authors.initials: P
authors.lastname: Keller
mesh_terms: D001187:Artificial Organs; D001672:Biocompatible Materials; D020724:Elastomers / Q000737:chemistry*; D066298:In Vitro Techniques; D050866:Liquid Crystals / Q000737:chemistry*; D046911:Macromolecular Substances; D008422:Materials Testing; D008954:Models, Biological; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D009132:Muscles / Q000737:chemistry*; D053758:Nanoparticles; D018462:Photobiology
chemical_list: D001672:Biocompatible Materials; D020724:Elastomers; D046911:Macromolecular Substances