Thiol-terminated hyperbranched polymer for DLP 3D printing: Performance evaluation of a low shrinkage photosensitive resin

In order to lower the volume shrinkage of the DLP 3D printing photosensitive resins during printing, a thiol-terminated hyperbranched polymer (T-HBP) was synthesized and introduced into the bisphenol A epoxy acrylate (EA) based photosensitive resin system. The obtained T-HBP was characterized by FTIR and ¹H NMR spectra, and the grafting rate of sulfhydryl was determined. The mechanical properties of the photosensitive resins were measured by tensile and impact strength measurement. The glass transition temperature of the photosensitive resins was analyzed by DSC and the impact fracture surface was observed by SEM. T-HBP exhibited a much lower viscosity than its linear counterparts, and the addition of thiol improved the curing speed of the photosensitive resins. When the amount of T-HBP added was 20 wt%, the shrinkage of the photosensitive resins was reduced by about 45.5% and the impact strength increased by 33.9% compared with the control. The macromolecular spherical structure of T-HBP effectively reduced the functional group density of the photosensitive resins. In addition, the thiol-acrylate photopolymerization introduced by T-HBP further reduced the volume shrinkage of the photosensitive resins.