GOALI/Collaborative Research: Autonomous Thermomechanical Fabrication of 3D Structures using Heat-Responsive Polymers

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

Autonomously fabricating macro-scale polymeric objects by subjecting a preform to a non-contact stimulus such as heat holds significant technological implications. For instance, it offers the ability to transform a preform (fabricated in simple, compact geometries) into target shapes on demand. It also offers the ability to simultaneously transform a large number of parts into target shapes by triggering them en masse using a globally applied stimulus. Hence, mass manufacturability emerges without an additional overhead. This Grant Opportunity for Academic Liaison with Industry (GOALI) award supports fundamental research on the self-assembly of 3D structures based on designs embedded at the molecular level in heat-responsive polymers. Research results can help spawning new technologies in applications such as biomedicine, where implants can be deployed into desired shapes and reshaped as-needed using an external stimulus. The first research objective is to establish the relationship between the spatiotemporal evolution of strain fields (leading to the creation of 3D helical structures) and controllable parameters (nematic director orientation and temperature). To achieve this objective, crosslinked, acrylate-based liquid crystalline polymers in twisted nematic configurations will be synthesized. Freely suspended polymer samples will be subjected to heat treatment with varying nematic director orientation (ranging from 0 to 45° with respect to the mid-plane of samples) and temperature (ranging from the glass transition temperature to close to the thermal decomposition temperature). The evolution of strain fields in these samples will be measured in situ using image analysis based characterization. The second research objective is to establish the effect of the displacement (preimposed on the sample) on the spatiotemporal evolution of torsional, bending strain fields (underpinning the creation of 3D prismatic and hierarchically supercoiled shapes). Various displacements (up to 20 percent of the length of the samples) will be imposed to samples. Spatiotemporal evolution of torsional, bending strain fields will be measured using imaging analysis based characterization.