Three-Dimensional Printable Photocurable Elastomer Composed of Hydroxyethyl Acrylate and Hydroxy Fatty Acid Derived from Waste Cooking Oil: An Innovative Strategy for Sustainable, Highly Flexible Resin Development

TL;DR

Scientists developed a flexible 3D printable material from waste cooking oil, offering a sustainable alternative with high flexibility and multiple useful properties.

Contribution

A new strategy to convert waste cooking oil into a photocurable elastomer with exceptional flexibility and multifunctional properties.

Findings

The WHFA/HEA elastomer achieves an elongation at break of 1184.66%, surpassing pure HEA by 360%.

The material shows weldability, reprocessability, pressure-sensitive adhesion, and biodegradability.

The optimized material has potential for use in flexible electronics and biomedical scaffolds.

Abstract

Waste cooking oil (WCO), a significant urban waste stream, presents untapped potential for synthesizing high-value materials. This study introduces an innovative “epoxidation-hydrolysis-blending” strategy to conveniently transform WCO into a highly flexible, photocurable elastomer suitable for 3D printing. Initially, WCO is converted into WCO-based hydroxy fatty acids (WHFA) via epoxidation and hydrolysis, yielding linear chains functionalized with multiple hydrogen-bonding sites. Subsequently, blending WHFA with hydroxyethyl acrylate (HEA) yields a novel photocurable WHFA/HEA elastomer. This elastomer exhibits excellent dimensional accuracy during vat photopolymerization 3D printing. Within the WHFA/HEA system, WHFA acts as a dual-functional modifier: its flexible alkyl chains enhance conformational freedom through plasticization while serving as dynamic hydrogen-bonding cross-linking sites that synergize with HEA chains to achieve unprecedented flexibility via reversible bond reconfiguration. Mechanical testing reveals that the optimized WHFA/HEA elastomer (mass ratio 1:3) exhibits ultra-high flexibility, with an elongation at break of 1184.66% (surpassing pure HEA by 360%). Furthermore, the elastomer demonstrates significant weldability (44.23% elongation retention after 12 h at 25 °C), physical reprocessability (7.60% elongation retention after two cycles), pressure-sensitive adhesion (glass interface adhesion toughness: 32.60 J/m2), and notable biodegradability (14.35% mass loss after 30-day soil burial). These properties indicate broad application potential in flexible electronics, biomedical scaffolds, and related fields. This research not only pioneers a low-cost route to multifunctional photocurable 3D printing materials but also provides a novel, sustainable solution for the high-value valorization of waste cooking oil.

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