Renewable Photopolymers: Transformation of Biomass Resources into Value-Added Products Under Light

Abstract

Light-induced cross-linking of liquid monomers has found widespread applications in various fields, such as dentistry, coatings, tissue engineering, and 3D printing. These processes typically rely on monomers derived from petrochemicals, which are volatile in price and are becoming increasingly depleted, compelling researchers to explore alternative sources from forestry and agricultural crops. The renewability of these resources makes them a promising option for developing substitutive materials with similar or superior properties. The various structural subunits in biomass offer alternative building blocks for petroleum-based photopolymers including the double bond-containing and hydrophobic fatty acids and terpenes, hydrophilic carbohydrates and proteins, aromatic furfural compounds from carbohydrates, and phenolic moieties in lignin. They can be transformed into photopolymers by the inherent or chemically introduced photocurable bonds. This review seeks to highlight recent advancements in transforming renewable platform chemicals into photocurable systems for photopolymerization processes and examines the thermomechanical properties and applications of the resulting cured materials. Furthermore, potential issues for improvement are also identified, such as the cost-effectiveness of biomass-based photopolymers and the risk in competition with food production. The perspectives on future directions for improving the renewability in this area are also given.

Improving the 3D Printability and Mechanical Performance of Biorenewable Soybean Oil-Based Photocurable Resins

“…The sample thickness was measured (thickness gauge Millitast 1080, MAHR GmbH, Göttingen, Germany) and corresponded to the cure depth for the specific energy required for curing; every sample was performed in duplicate. Further on, the penetration depth and the energy needed for the starting point of the transition from liquid to solid were calculated from Equation (5).…”

“…This is particularly challenging for new technologies such as vat photopolymerization 3D printing due to the limited availability of environmentally friendly photocurable polymers [1]. In recent years, new biomaterials have been modified and tested for photocurable printing, such as polyethylene glycol or polycaprolactone [2][3][4] or biomass compounds such as vegetable oils, polysaccharides, lignin, terpene-derived compounds or proteins [5]. Specifically, vegetable oils (VOs) are frequently used in manufacturing industries because of their abundant C=C bonds which are simple to epoxidize; epoxidized vegetable oils (EVOs) are abundant, economic, renewable, sustainable, nontoxic and environmentally friendly [6].…”