Template-free Reconfigurable Nematic Defect-arrays for designing Self-organisable Topological Three-dimensional Elastomer responsive-Rafts


CALL: 2017

DOMAIN: MS - New Functional and Intelligent Materials and Surfaces

FIRST NAME: Venkata Subba Rao

LAST NAME: Jampani



HOST INSTITUTION: University of Luxembourg

KEYWORDS: Liquid crystal elastomers, Actuators, Topological defects, Reconfigurable defect arrays, Self-organization, Polymerizable templates, Laser writing, Color-responsive sensors.

START: 2017-11-15

END: 2020-10-14

WEBSITE: https://www.uni.lu

Submitted Abstract

Liquid crystal elastomers (LCEs) are rapidly gaining attention in today’s trend in materials science and technology. LCEs are weakly cross-linked polymers yet containing the LC core embedded into the polymer network which orients in a preferred direction thus an orientational symmetry breaking which reduces the conformational freedom of the polymer backbone, with a consequent entropy cost. When an external stimulus (e.g. heat or light) is applied that considerably reduces the long-range order, the symmetry breaking influence is reduced or disappears, allowing the polymer to adapt a more isotropic random coil conformation, that—due to the crosslinks—collectively results in a reversible macroscopic shape change. The key aspects defining the type of motion and strength of actuation are the quality of alignment in the LCE ground state and its topology. So far, LCE actuator design is limited to spherical geometries, due to the interfacial tension phenomena that govern microfluidic production, or to films produced on lithographically-patterned guiding substrates. To fully harness the potential of LCEs as soft actuators, we need alternative approaches to pattern the director field, preferably in 3D, across large areas. To this end, we here propose template-free reconfigurable nematic defect-arrays (‘trend’) for designing self-organizable topological three-dimensional elastomer responsive-rafts (‘setter’) for macroscale shape-changing systems with microscale motion control. We strongly believe that this approach offers many different topological structures and full control in defining the size and location of the defect. The proposed system is expected to deliver a smart, responsive, flexible material with functions of variable stiffness/variable friction, monolithic actuation, shear sensors, and stand-alone visible light active volatile organic compound (VOCs) sensors. More importantly, this system is free from being bound to specific fixed substrates, thus allowing it to be used in various challenging environments and also it opens a unique platform for studying the structure-property relationship of LCEs.

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