In this study, we design, fabricate and characterize a novel unimorph-like structure where a shape memory polymer (SMP) is actuated using a magneto-active elastomer&nbsp;(MAE), resulting in&nbsp;contactless and&nbsp;large&nbsp;deformation&nbsp;shape change. The model materials used are: a two-part&nbsp;elastomer, iron oxide microparticles, and a rapid cure epoxy. Combining the elastomer with the iron oxide particles&nbsp;results&nbsp;in an&nbsp;MAE actuator,&nbsp;such that&nbsp;application of an external magnetic field induces dipoles in the iron oxide particles, resulting in the actuation of the MAE. The shape memory epoxy polymers are deformed&nbsp;at an elevated temperature and cooled to lock-in the&nbsp;temporary programmed shape.&nbsp; Subsequent exposure to elevated&nbsp;temperature can then recover a permanent geometry. In a first step,&nbsp;the layered unimorph structure&nbsp;is fabricated using casting techniques where the&nbsp;SMP serves&nbsp;as the ‘passive’ substrate, and the MAE&nbsp;is&nbsp;cast on top of this substrate or joined post-processing using adhesives. To demonstrate shape change, the&nbsp;unimorph&nbsp;is&nbsp;heated beyond the transition temperature of the epoxy, and&nbsp;a magnetic field&nbsp;is&nbsp;applied&nbsp;to deform the structure. Upon cooling, the shape change&nbsp;is&nbsp;locked into place.&nbsp;This configuration serves&nbsp;as proof-of-concept that&nbsp;the&nbsp;proposed&nbsp;magnetically-responsive polymers are capable of eliciting the shape change of an SMP through bending in response to an external&nbsp;magnetic&nbsp;stimulus. After demonstrating feasibility,&nbsp;the&nbsp;next step is to&nbsp;additively manufacture&nbsp;both the SMP and&nbsp;MAE&nbsp;by developing and tuning MAE and SMP resin formulations for printability.&nbsp;Printability&nbsp;is&nbsp;assessed by characterizing viscosities, gelation times, and extent of cure.&nbsp;The bending response of the layered structure&nbsp;is&nbsp;characterized as a function of magnetic field, material composition, geometric parameters, and AM printing process settings.&nbsp;&nbsp;&nbsp;The&nbsp;outcome of this research is to&nbsp;enable&nbsp;additive manufacturing&nbsp;of smart materials and devices that can&nbsp;monitor and adapt to their environment.&nbsp;The medical device industry in particular stands to benefit from customizable devices&nbsp;that adapt their shape&nbsp;for particular patients, diseases, and/or stage of healing.

Design and Characterization of a Multilayered Multifield-Actuated Polymer Unimorph

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

ASME 2021 Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2021)

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