Multimaterial 4D Printing with Tailorable Shape Memory Polymers

TLDR

The authors aim to develop a high‑resolution multimaterial 4D printing method for shape‑memory polymer architectures and to model their behavior. They employ projection micro‑stereolithography with photo‑curable methacrylate copolymers, a high‑contrast digital micro‑display, and an automated material‑exchange system to fabricate and computationally simulate the nonlinear, time‑dependent response of the structures. Simulation results match experimental measurements for single and multimaterial components, demonstrating the method’s utility for designing SMP 3D structures.

Abstract

Abstract We present a new 4D printing approach that can create high resolution (up to a few microns), multimaterial shape memory polymer (SMP) architectures. The approach is based on high resolution projection microstereolithography (PμSL) and uses a family of photo-curable methacrylate based copolymer networks. We designed the constituents and compositions to exhibit desired thermomechanical behavior (including rubbery modulus, glass transition temperature and failure strain which is more than 300% and larger than any existing printable materials) to enable controlled shape memory behavior. We used a high resolution, high contrast digital micro display to ensure high resolution of photo-curing methacrylate based SMPs that requires higher exposure energy than more common acrylate based polymers. An automated material exchange process enables the manufacture of 3D composite architectures from multiple photo-curable SMPs. In order to understand the behavior of the 3D composite microarchitectures, we carry out high fidelity computational simulations of their complex nonlinear, time-dependent behavior and study important design considerations including local deformation, shape fixity and free recovery rate. Simulations are in good agreement with experiments for a series of single and multimaterial components and can be used to facilitate the design of SMP 3D structures.