Bio-based and hydrolytically degradable hydroxyurethane acrylates as photocurable thermosets

This study focuses on the synthesis of bio-based and hydrolytically degradable photocurable thermosets made from hydroxyurethane acrylates (HUA). The hydroxyurethanes (HUs) are prepared from the reaction between ethylene carbonate and a bio-based diamine, Priamine 1074. Subsequently, the HU initiates the ring opening polymerization of epsilon-caprolactone (CL), resulting in telechelic groups of 5 CL units at both ends of the HU. The resulting HU-CL5 is finally acrylated to prepare the degradable HUA (HU-CL5-A) with transformations confirmed following each step via proton nuclear magnetic resonance (H-1-NMR) and Fourier-transform infrared (FTIR) spectroscopies. HU-CL5-A is photocured with 4-acryloylmorpholine (ACMO) as a photosensitive reactive diluent. The photocurable thermosets exhibit slight water swelling (swelling index of 46%), as Priamine 1074 and ACMO are hydrophobic and hydrophilic, respectively, leading to the slow and partial degradation of the films in water at 85 degrees C for 14 days. The cleavage of the CL units from the film networks is proven via H-1-NMR and FTIR, which demonstrates the main objective of this study in synthesizing photocurable and degradable HUA resins.