Toward robust solid propellant grains by vat photopolymerization 3D printing

The block copolyether (HTPE) composed of polytetrahydrofuran and polyethylene glycol holds significant promise for preparing insensitive solid propellants. However, no corresponding photosensitive binder formulation has been available for the photopolymerization 3D printing of such propellants. In this study, a photosensitive binder formulation is developed using acrylate-terminated polyether (ATPE), obtained through end-group modification of HTPE, as the oligomer, hydroxyethyl methacrylate (HEMA) and caprolactone acrylate (CA) as reactive diluents, trimethylolpropane triacrylate (TMPTA) as the crosslinker, and N-butyl-N-(2-nitroxyethyl) nitramine (Bu-NENA) as the plasticizer. The effects of ATPE content, crosslinker content, and plasticizer ratio on mechanical properties are systematically investigated using orthogonal experimental. Based on the identified optimal levels, four distinct ATPE-HC# photosensitive binder formulations with varying ATPE contents are ultimately determined. The optimized ATPE-HC# binder films exhibit a low glass transition temperature, favorable processing characteristics, and excellent compatibility with Bu-NENA, ammonium perchlorate (AP), cyclotrimethylenetrinitramine (RDX), and aluminum powder. The results of DLP 3D printing show that ATPE-HC5# has good applicability for rapid photocuring 3D printing of solid propellants. This photosensitive binder strategy, derived from the HTPE molecular structure, not only significantly enhances the production efficiency of solid propellant but also has higher mechanical strength than the thermally cured HTPE solid propellant.