Synthesis and photopolymerization kinetics of acrylate-terminated polyether for additive manufacturing

Abstract

The development of photocuring 3D printed solid propellants is limited by photosensitive binders. Numerous commercial photosensitive oligomers used as binders for solid propellants fail to meet the performance criteria related to processability, mechanical properties, and safety. Modifying established binders that have been used in solid propellants offers a more cost-effective and dependable approach to prepare photosensitive binders. By utilizing the addition reaction between the isocyanate group in 2-isocyanatoethyl acrylate (AOI) and the hydroxyl group in hydroxyl-terminated polyether (HTPE), we successfully modified HTPE to synthesize acrylate-terminated polyether (ATPE), which exhibits the capability of undergoing free radical polymerization. The molecular weight distribution of HTPE and ATPE, as well as the correlated characteristic absorption peaks, were analyzed using gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR) techniques, respectively. The excellent initiation properties of photoinitiator 819, serving as a photosensitive additive of ATPE, were elucidated by comparing the differences in molar absorption coefficients, initiator decomposition rates, and initiator decomposition rate constants among photoinitiators 184, 819, TPO and TPO-L under UV light at 405 nm. The thermal effects resulting from the photopolymerization of ATPE were investigated using photo differential scanning calorimetry (Photo-DSC), and the characteristics of the photopolymerization reaction, along with polymerization kinetic parameters such as the polymerization rate, growth polymerization rate constant (k_p), and termination polymerization rate constant (k_t), were analyzed in detail. The synthesis and photopolymerization kinetics of ATPE presented in this work provide valuable support for the photopolymerization 3D printing of solid propellants.