Resin, cure, and polymer properties of photopolymerizable resins containing bio-derived isosorbide

We have developed photocurable bio-derived isosorbide (meth)acrylates for use in photoinitiated additive manufacturing (AM). We have shown that the viscosity of isosorbide-based resins obeyed logarithmic rule of mixtures, and the viscosity values were significantly lower than that of commercial stereolithography (SLA) resins as well as various other urethane (meth)acrylates and bisphenol A (meth)acrylates-containing blends. Using isobornyl acrylate or 4-acryloylmorpholine as reactive diluents, we were able to reduce the brittleness of the isosorbide-based polymers and retain high glass transition temperatures (T_g) of up to 231°C. The isosorbide-based resins were still somewhat brittle but had both greater T_g and strength relative to analogous bisphenol A dimethacrylate resins. Addition of oligomeric urethane (meth)acrylate crosslinkers further improved the mechanical properties of the polymers, whereby the strength approximately doubled to 55 MPa at 25°C, while maintaining high thermal properties, T_g > 190°C, and low viscosities, <140 cP, that are desirable for photoinduced AM applications. Furthermore, we were able to print this resin using SLA which produced specimens with similar moduls, but reduced strength relative to photocured resins and a commercial high temperature SLA resin.