Self-folding behavior of bilayer films actuated by liquid crystal elastomers

Yi-Hung Lin; Braden Starver; Bryan Beckingham; Russell W. Mailen

doi:10.1117/12.3014639

9 May 2024 Self-folding behavior of bilayer films actuated by liquid crystal elastomers

Yi-Hung Lin, Braden Starver, Bryan Beckingham, Russell W. Mailen

Proceedings Volume 12947, Behavior and Mechanics of Multifunctional Materials XVIII; 129470C (2024) https://doi.org/10.1117/12.3014639
Event: SPIE Smart Structures + Nondestructive Evaluation, 2024, Long Beach, California, United States

Abstract

Liquid crystal elastomers (LCEs) films enable thermally responsive shape change. Mesogenic segments in the elastomeric network can be aligned into crystalline domains via mechanical deformation of the film. If subjected to a second-stage UV cure in the deformed shape, the crystalline domains are retained upon release of the external load. This induces a temporary shape in the LCE. Subsequent heating of the LCE above the nematic-to-isotropic temperature disorders the liquid crystals, and strain energy stored in the elastomer causes the LCE to return to the undeformed. In a reversible manner, the LCE returns to the temporary shape when cooled. In this work, we use thermally responsive LCE films applied to passive thin films, such as mylar and Kapton. The passive film enhances the mechanical strength and stiffness of the film but prevents alignment of the LCE crystalline domains through stretching. Instead, these bilayer films are restricted to folding deformations, wherein the LCE layer is used to induce thermally responsive shape change. We study the effects of layer thickness ratios on the reversibly self-folding bilayer films. The LCE films are synthesized directly on the passive film layer using a two-stage thiol-acrylate Michael addition and photopolymerization (TAMAP) reaction in which the first stage is a thermal cure, and the second stage is a UV cure. We demonstrate the reversible shape change between flat and folded states, and quantify the shape change in terms of the shape fixity and recovered flatness ratios. Potential applications for this system are actuators for deployable structures and soft robotics.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Yi-Hung Lin, Braden Starver, Bryan Beckingham, and Russell W. Mailen "Self-folding behavior of bilayer films actuated by liquid crystal elastomers", Proc. SPIE 12947, Behavior and Mechanics of Multifunctional Materials XVIII, 129470C (9 May 2024); https://doi.org/10.1117/12.3014639

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available