Preparation of Elastic Photocurable Resins for Vat Photopolymerization 3D Printing and Application in Surface Functionalization

A photosensitive polyurethane prepolymer with alternating soft and hard segments was synthesized using polyethylene glycol (PEG400) and hexamethylene diisocyanate (HDI). At the same time, hydroxyethyl methacrylate (HEMA) was employed as a chain terminator to introduce acrylate functionalities. The successful formation of urethane linkages was confirmed by Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. At a soft-to-hard segment molar ratio of 1:1.5, the resulting photopolymerized elastomer exhibited optimal mechanical performance, achieving a tensile strength of 7.8 MPa and an elongation at break of 275%. Furthermore, photopolymerization with lauryl methacrylate (LMA) imparted the material with excellent flexibility. The incorporation of silane-coupling-agent-modified nano-SiO 2 as a reinforcing filler further improved the mechanical strength of the composite. By surface-loading an ionically conductive hydrogel, the material was employed to fabricate a tensile sensor via vat photopolymerization 3D printing, demonstrating its potential in flexible sensing applications.