Glycidyl Azide Polymer Crosslinked Through Triazoles by Click Chemistry: Curing, Mechanical and Thermal Properties

摘要

Glycidyl azide polymer (GAP) was cured through "click chemistry" by reaction of the azide group with bis-propargyl succinate (BPS) through a 1,3-dipolar cycloaddi-tion reaction to form 1,2,3-triazole network. The properties of GAP-based triazole networks are compared with the ure-thane cured GAP-systems. The glass transition temperature (T_g), tensile strength, and modulus of the system increased with crosslink density, controlled by the azide to propargyl ratio. The triazole incorporation has a higher T_g in comparison to the GAP-urethane system (T_g-20°C) and the networks exhibit biphasic transitions at 61 and 88 °C. The triazole curing was studied using Differential Scanning Calo-rimetry (DSC) and the related kinetic parameters were help- ful for predicting the cure profile at a given temperature. Density functional theory {DFT)-based theoretical calculations implied marginal preference for 1,5-addition over 1,4-addition for the cycloaddition between azide and propargyl group. Thermogravimetic analysis (TG) showed better thermal stability for the GAP-triazole and the mechanism of decomposition was elucidated using pyrolysis GC-MS studies. The higher heat of exothermic decomposition of triazole adduct (418 kJ·mol~(-1)) against that of azide (317 kJ·mol~(-1)) and better mechanical properties of the GAP-triazole renders it a better propellant binder than the GAP-urethane system.