Photocurable elastomers with tunable mechanical properties for 3D digital light processing printing

Abstract

Digital light processing (DLP), a subclass of vat photopolymerization, is one of the most efficient additive manufacturing (AM) techniques that can be used to print complex objects with high precision at a greater speed than those of the other AM processes. However, printed objects are typically brittle because networks of cured resins are highly crosslinked, thereby limiting their range of possible applications. Currently, only a few commercial photocurable elastomers used for DLP can produce materials with moderate tensile strain, poor strength, and low modulus. Herein, we present a simple method for preparing photocurable resins that not only exhibit a low viscosity at room temperature, but also demonstrate tunable elasticity and strength. These novel resins are prepared from commercially available acrylate-based oligomers and monomers, which are appropriately selected to achieve a variety of mechanical properties. Subsequenlty, key parameters are investigated, including the viscosity of the uncured resin, critical energy at which the resin begins to solidify (Ec), depth of penetration of the curing light (Dp), and degree of curing. The viscosities of the developed resins range between 0.85 and 3.10 Pa s, and their curing and mechanical properties can be adjusted by varying the oligomer-to-monomer weight ratio. The Ec (6.9–9.2 mJ cm−2) and Dp (192–271 μm) of all the uncured resins are obtained from the working curves. The developed photoelastomers exhibit a wide range of tensile properties (tensile strain of 110–365%, tensile strength of 0.8–10 MPa, and modulus of 0.5–10 MPa), thereby facilitating their use in various applications.