Synthesis and Properties of n-Al/Fluorinated Polyurethane Binders Prepared by Simultaneous Addition Polymerization and Catalyst-Free Azide-Alkyne Click Modification with Fluorinated Reactive Plasticizers

The feasibility of the new concept of fluorinated reactive plasticizer (FRP) was investigated improve the processability, prevent the migration of plasticizers, and enhance the energetic performance. Three types of FRPs, long fluorinated ester-linkage FRPs, short fluorinated ester-linkage FRPs, and short fluorinated formal-linkage FRPs, were synthesized by esterification and acetalization, and characterized by H-1 and C-13 NMR spectroscopy. The length of the fluorocarbon in the FRPs affected the miscisiblity and plasticization with PGT prepolymers, only short fluorinated ester-linkage and formal-linkage FRPs improved the processability. From the click reactivity and activation energy measured by H-1 NMR and DSC, the FRPs with a methylene spacer (n = 1) between the electron-withdrawing group and neighboring alkyne group completed the click reaction with a reasonable rate at 60 degrees C. Thermal analysis of the n-Al/FRP-incorporated PGT-based PU binders using DSC with a high pressure crucible confirmed the exothermic thermite reaction and quantified the enthalpy of the reaction to evaluate the energetic performance.