title: Dynamic self-stiffening in liquid crystal elastomers.
abstract: Biological tissues have the remarkable ability to remodel and repair in response to disease, injury and mechanical stresses. Synthetic materials lack the complexity of biological tissues, and man-made materials that respond to external stresses through a permanent increase in stiffness are uncommon. Here we report that polydomain nematic liquid crystal elastomers increase in stiffness by up to 90% when subjected to a low-amplitude (5%), repetitive (dynamic) compression. Elastomer stiffening is influenced by liquid crystal content, the presence of a nematic liquid crystal phase and the use of a dynamic as opposed to static deformation. Through rheological and X-ray diffraction measurements, stiffening can be attributed to a mobile nematic director, which rotates in response to dynamic compression. Stiffening under dynamic compression has not been previously observed in liquid crystal elastomers and may be useful for the development of self-healing materials or for the development of biocompatible, adaptive materials for tissue replacement.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Rice University, MS-362, 6100 Main Street, Houston, Texas 77005, USA.
authors.forename: Aditya
authors.initials: A
authors.lastname: Agrawal
authors.forename: Alin C
authors.initials: AC
authors.lastname: Chipara
authors.forename: Yousif
authors.initials: Y
authors.lastname: Shamoo
authors.forename: Prabir K
authors.initials: PK
authors.lastname: Patra
authors.forename: Brent J
authors.initials: BJ
authors.lastname: Carey
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
authors.forename: Walter G
authors.initials: WG
authors.lastname: Chapman
authors.forename: Rafael
authors.initials: R
authors.lastname: Verduzco
mesh_terms: D004129:Dimethylpolysiloxanes / Q000737:chemistry; D020724:Elastomers / Q000737:chemistry*; D050866:Liquid Crystals / Q000737:chemistry*; D055595:Mechanical Phenomena; D013314:Stress, Mechanical
chemical_list: D004129:Dimethylpolysiloxanes; D020724:Elastomers