Four-dimensional printing of shape memory polyurethanes with high strength and recyclability based on Diels-Alder chemistry

Abstract

A type of polyurethane with high mechanical performance, excellent recycling ability and shape memory property based on Diels-Alder (DA) reactions has been fabricated through digital light processing (DLP) 3D printing. Firstly, polyurethane acrylate with DA-adduct is synthesized, and then compounded with reactive diluent and photoinitiators to get a series of photopolymer resins. Benefiting from the high curing rate and good fluidity, one type of photopolymer is applied in DLP 3D printing. The excellent mechanical and recycling properties of the cured polymers are proved through tensile tests. The printed samples exhibit remarkable shape memory performance with the shape fixity and recovery ratios of 96.4 ± 0.1% and 99.3 ± 0.3%, respectively and high shape recovery stress of 10.1 MPa, which is very high for shape memory polymers.