3D Printing Resins Involving Exclusively Bio-Based Compounds─Can Precursors for Commercial Vat Photopolymerization Comprise Only Biobased Molecules?

Abstract

Vat photopolymerization exemplifies one of the most attractive and prospective processing approaches, producing unique prototypes, specifically functional systems, or biocompatible products in the next generation of biobased materials. This work summarizes and presents specific strategies for developing chemical solutions for three-dimensional (3D)-printable resins derived exclusively from biobased compounds. The photocurable systems used in additive manufacturing require a primary reactive resin precursor. Usually, rheological modifications that regulate the flow characteristics of the polymerizable main system require the use of reactive diluents, which are low-molecular-weight, low-viscosity, and polymerizable. Such systems often exhibit excessive volatility, resulting in environmental issues such as increased VOCs or hazardous chemical character. This overview presents and describes the main reactive resin precursors, based on bioderived polyesters and terpene-based systems, along with fully biobased reactive diluents synthesized from biotechnological products (itaconic acid) and other sources (biophenols). Lastly, the partly and fully biobased photoinitiators, produced from sources, such as riboflavin, coumarin, or curcumin, are introduced as an alternative to the highly hazardous and toxic commercial photoinitiators, such as BAPO and TPO, which pose serious health hazards. Fully biobased precursors stand in this perspective as substances obtainable from alternative feedstocks to petroleum-based ones (e.g., biotechnological production, extraction from biomass, and reformulation of complex substances). This work reviews the reported options and experimental findings and suggests the most promising pathways to environmentally friendly vat photopolymerization resins.