One-Pot Printing of Robust Multimaterial Devices

TL;DR

This paper introduces a novel 3D printing method using a single resin that can produce multimaterial devices with a wide range of properties, robust interfaces, and stability, enabling complex architectures like a wearable braille display.

Contribution

A new ternary sequential reaction scheme for 3D printing that creates diverse, stable multimaterial structures within a single resin composition.

Findings

Young's Moduli range from 400 kPa to 1.6 GPa

Achieved 500x change in modulus within 1 mm

Enhanced toughness by 10x compared to single-property materials

Abstract

Polymer 3D printing is a broad set of manufacturing methods that permit the fabrication of complex architectures, and, as a result, numerous efforts focus on formulating processible chemistries that produce desirable material behavior in printed parts. However, current resin chemistries typically result in a single fixed set of properties once fully polymerized, a fact that poses significant engineering challenges to obtaining multimaterial devices. As an alternative to single-property materials, we introduce a ternary sequential reaction scheme that exhibits diverse multimaterial properties by profoundly altering the polymer microstructure from within a single resin composition. In this system, the photodosage during 3D printing sets both the shape and extent of conversion for each subsequent reaction. This different polymerization mechanisms of the subsequent stages yield disparate crosslink densities and viscoelastic properties. As a result, our materials possess Young's Moduli spanning over three orders of magnitude (400 kPa < E < 1.6 GPa) with smooth transitions between soft and stiff regions. We successfully pattern a 500x change in modulus in under a millimeter while the sequential assembly of our polymer networks ensures robust interfaces and enhances toughness by 10x compared to the single property materials. Most importantly, the final objects remain stable to UV and thermal aging, a key limitation to applications of previous multimaterial chemistries. We demonstrate the ability to 3D print intricate multimaterial architectures by fabricating a soft, wearable braille display.