(Meth)acrylate-Free Three-Dimensional Printing of Bio-Derived Photocurable Resins with Terpene- and Itaconic Acid-Derived Poly(ester-thioether)s

Abstract

Vat photopolymerization, a very efficient and precise object manufacturing technique, still strongly relies on the use of acrylate- and methacrylate-based formulations because of their low cost and high reactivity. However, the environmental impact of using fossil fuel-based, volatile, and toxic (meth)acrylic acid derivatives is driving the scientific community toward the development of alternatives that can match the mechanical performance and three-dimensional (3D) printing processability of traditional photocurable mixtures but are made from environmentally friendly building blocks. Herein, itaconic acid is polymerized with polyols derived from naturally occurring terpenes to produce photocurable poly(ester-thioether)s. The formulation of such polymers using itaconic acid-based reactive diluents allows the preparation of a series of (meth)acrylate-free photocurable resins, which can be 3D printed into solid objects. Extensive analysis has been conducted on the properties of photocured polymers including their thermal, thermomechanical, and mechanical characteristics. The findings suggest that these materials exhibit properties comparable to those of traditional alternatives that are created using harmful and toxic blends. Notably, the photocured polymers are composed of biobased constituents ranging from 75 to 90 wt %, which is among the highest values ever recorded for vat photopolymerization applications.

Photocurable Itaconic Acid-Functionalized Star Polycaprolactone in Biobased Formulations for Vat Photopolymerization

“…Grindsted Soft-N-Safe (9-hydroxystearic acid monoglyceride triacetate, SNS) was purchased from Danisco (Brabrand, Denmark). 1,4-Butanediyl bis­(methyl itaconate) was prepared as previously described . All other chemicals were purchased from Sigma-Aldrich (Saint-Louis, MO) and used as received.…”

“…With the aim of improving the sustainability of SLA-based manufacturing, the biobased building block itaconic acid is emerging since it is industrially obtained by the fermentation of sugars . Its photocurable moiety opens the possibility of a complete replacement of acrylic and methacrylic acid derivatives in SLA. , Moreover, the double carboxylic functionality allows for its incorporation into photocurable polyesters and poly­(ester–amides) and for the preparation of small diesters that have been recently reported as partially biobased reactive diluents. − …”