Utilizing acrylic polyhydroxyurethane with tunable functionality as a photocurable resin for 3D printing

Abstract

To improve physical properties, polyurethane (PU) with urethane bonds is a promising solution. Particularly, polyhydroxyurethane (PHU) prepared via the non-isocyanate PU (NIPU) method is garnering attention because the urethane bond in the main chain enhances physical properties through intermolecular hydrogen bonding with -OH groups. This type of PHU has been extensively studied as a hybrid PHU (H-PHU) for various industrial applications. Herein, we introduce polyhydroxyurethane methacrylate (PHUMA), which can grow from the main backbone based on abundant crosslinking points as a H-PHU. In addition, the degree of substitution can be easily tuned by functionalizing the hydroxy group with the methacrylate group within one molecule. Furthermore, through the conventional synthesis method, end-group urethane methacrylate (EUMA) was prepared as a comparison group with the same polypropylene glycol (PPG)-based urethane methacrylate structure and similar molecular weight as PHUMA. Due to the rich crosslink density characteristic of PHUMA, it was possible to use it as a photocurable resin for 3D printing by mixing it with 2-hydroxyethyl acrylate (HEA) as a diluent monomer and bisacylphosphine oxide (BAPO) as a photo-initiator. As a result, it was confirmed that the intrinsic, mechanical, and thermal properties in the gelation of 3D-printed specimens with PHUMA by digital light processing (DLP) were superior to those with EUMA.