3D Printable Polylactone/2-hydroxylethyl acrylate Networks with Programmable Mechanical Properties towards Tissue Engineering

Abstract

Photopolymerisation-based 3D printing of biocompatible materials enables the fabrication of highly accurate, customised scaffolds; however, the resulting covalently crosslinked networks typically exhibit fixed mechanical properties. Here, we introduce 3D-printed polyester/acrylate hydrogels with adjustable mechanical properties enabled by chemically orthogonal controlled dual crosslinking. The resin formulation consists of a tetra-cinnamic-acid-functionalised copolyester, poly(valerolactone-co-caprolactone) (P(CL-co-VL)-CA), blended with 2-hydroxyethyl acrylate (HEA) and the radical crosslinker pentaerythritol tetraacrylate (PETA). Owing to the significantly faster photoreactivity of the acrylate groups, printing proceeds via HEA radical polymerisation to form a soft primary network while preserving pendant cinnamic acid functionalities. A secondary network is subsequently introduced through UV-induced [2+2] cycloaddition of the cinnamate groups during post-curing. By controlling the post-printing light exposure time, the extent of P(CL-co-VL)-CA crosslinking, and hence the elastic modulus of the resulting double-network scaffolds, can be tuned from 0.3 to 1.8 MPa without altering the printed dimensions. Both single- and double-crosslinked P(CL-co-VL)-CA/HEA hydrogels supported high levels of cell proliferation. This work demonstrates a versatile strategy for generating, mechanically adaptable 3D objects from a single resin formulation through post-printing modulation.