Preparation and characterization of photocurable fluorinated polyether‐based reactive inks

Abstract

Photocurable polymer provides fast curable properties via ultraviolet (UV) light for 3D-printed propellants. This work outlines the preparation and characterization of photocurable fluorinated polyether-based reactive inks.Acrylate-terminated poly-2-((2,2,3,3,3-pentafluoropropoxy)-methyl) ethylene oxide (P5F-AA) was synthesized as photocurable binder through the esterification of acrylic acid, and the terminal hydroxyl group of poly-2-((2,2,3,3,3pentafluoropropoxy)-methyl) ethylene oxide (P5F), which was synthesized through cationic ring-opening polymerization of 2-((2,2,3,3,3-pentafluoropropoxy)methyl) oxy-ethane (PFEE) by using butane diol as initiator. In comparison with P5F, P5F-AA had a lower glass transition temperature (T g ) of À63.3 C. A new type of photocurable resin, which may be used for additive manufacturing of energetic materials, was prepared via UV radiation in an LED UV curing tank by using P5F-AA as prepolymer, diphenyl (2,4,6-trimethyl benzoyl) phosphine oxide (TPO) as photo-initiator, and tri-fluoroethyl acrylate (3F-AA) and 1,6-hexanediol diacrylate (HDDA) as mono-and multifunctional diluents, respectively. When the mass ratio of P5F-AA/3F-AA/HDDA binder matrix was 1:1:0.5, the sample exhibited maximal mechanical strength of 6.56 MPa with elongation at break of 13.38%, which was due to the introduction of HDDA effectively increasing the "entanglement" between molecular chains. Thermogravimetric analysis (TGA-DTG) was utilized to evaluate the ability to decompose thermally of the binder matrix, and the results showed the initial degradation temperature started at nearly 181 C and two consecutive stages in thermal decomposition. Overall, the obtained results from the different techniques suggested that P5F-AA/3F-AA/HDDA binder matrix may be a photocurable reactive ink for 3D-printed propellants, which would provide a certain reference value and guiding importance for design of reactive inks.