title: Preparation of biomimetic photoresponsive polymer springs.
abstract: Polymer springs that twist under irradiation with light, in a manner that mimics how plant tendrils twist and turn under the effect of differential expansion in different sections of the plant, show potential for soft robotics and the development of artificial muscles. The soft springs prepared using this protocol are typically 1 mm wide, 50 μm thick and up to 10 cm long. They are made from liquid crystal polymer networks in which an azobenzene derivative is introduced covalently as a molecular photo-switch. The polymer network is prepared by irradiation of a twist cell filled with a mixture of shape-persistent liquid crystals, liquid crystals having reactive end groups, molecular photo-switches, some chiral dopant and a small amount of photoinitiator. After postcuring, the soft polymer film is removed and cut into springs, the geometry of which is determined by the angle of cut. The material composing the springs is characterized by optical microscopy, scanning electron microscopy and tensile strength measurements. The springs operate at ambient temperature, by mimicking the orthogonal contraction mechanism that is at the origin of plant coiling. They shape-shift under irradiation with UV light and can be pre-programmed to either wind or unwind, as encoded in their geometry. Once illumination is stopped, the springs return to their initial shape. Irradiation with visible light accelerates the shape reversion.
authors: Bio-inspired and Smart Materials, MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands.
authors: Supitchaya
authors: S
authors: Iamsaard
authors: Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, UK.
authors: Elise
authors: E
authors: Villemin
authors: Bio-inspired and Smart Materials, MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands.
authors: Federico
authors: F
authors: Lancia
authors: Bio-inspired and Smart Materials, MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands.
authors: Sarah-Jane
authors: SJ
authors: Aβhoff
authors: Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Oxford, UK.
authors: Stephen P
authors: SP
authors: Fletcher
authors: Bio-inspired and Smart Materials, MESA+ Institute for Nanotechnology, University of Twente, Enschede, the Netherlands.
authors: Nathalie
authors: N
authors: Katsonis
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D040761:Biomimetic Materials / Q000737:chemistry*; D032701:Biomimetics / Q000379:methods*; D050866:Liquid Crystals / Q000737:chemistry*; D055668:Photochemical Processes; D011108:Polymers / Q000737:chemistry*; D013718:Tensile Strength; D014466:Ultraviolet Rays
chemical_list: D001391:Azo Compounds; D011108:Polymers; C422409:liquid crystal polymer; C009850:azobenzene