4D-printable photocurable pressure sensitive adhesives derived from waste cooking oil

Abstract

This study pioneers a sustainable strategy to convert waste cooking oil (WCO) into multifunctional 4D-printable photocurable pressure-sensitive adhesives (PSAs), addressing critical challenges in high value-added utilisation of WCO and industrial demand for adaptive, eco-friendly materials. Through sequential epoxidation and esterification, WCO was transformed into epoxy waste oil methacrylate (EWOMA), a photocurable monomer. Blending EWOMA with flexible acrylates – hydroxypropyl acrylate (HPA) or cyclohexyl acrylate (CHA) – yielded two novel PSA systems compatible with LCD 3D printing and conventional coating methods. Optimised formulations of EWOMA-CHA system achieved commercial-level adhesion, with interfacial toughness reaching 499.5 J/m2 (PMMA), 412 J/m2 (glass) and 222.92 J/m2 (steel). Molecular simulations revealed that the inclusion of flexible end-group molecules, particularly CHA, significantly enhanced the polymer network's flexibility and structural adaptability. This optimisation improved the distribution of hydrogen bonding both within the system and at the adhered surface, thereby strengthening adhesion and boosting PSA performance. Beyond adhesion, these PSAs demonstrated exceptional multifunctionality: high flexibility (elongation at break: 162.0% for EWOMA-CHA), thermally induced shape memory (room-temperature deformation/recovery, fixation at −15°C), and biodegradability (11.52% weight lossin 45-day soil burial). As a low-cost, scalable platform, these WCO-based 4D-printable PSAs enable eco-industrial innovation for biomedical, robotics, packaging, and so on.