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Glycidyl Azide Polymer Crosslinked Through Triazoles by Click Chemistry: Curing, Mechanical and Thermal Properties
Author(s) -
Reshmi Sasidhara K.,
Vijayalakshmi K. P.,
Thomas Deepthi,
Arunan E.,
Reghunadhan Nair C. P.
Publication year - 2013
Publication title -
propellants, explosives, pyrotechnics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.56
H-Index - 65
eISSN - 1521-4087
pISSN - 0721-3115
DOI - 10.1002/prep.201200036
Subject(s) - azide , cycloaddition , differential scanning calorimetry , glass transition , curing (chemistry) , propargyl , thermal decomposition , click chemistry , polymer chemistry , thermosetting polymer , triazole , exothermic reaction , thermal stability , materials science , chemistry , polymer , organic chemistry , thermodynamics , catalysis , physics
Glycidyl azide polymer (GAP) was cured through “click chemistry” by reaction of the azide group with bispropargyl succinate (BPS) through a 1,3‐dipolar cycloaddition reaction to form 1,2,3‐triazole network. The properties of GAP‐based triazole networks are compared with the urethane 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 Calorimetry (DSC) and the related kinetic parameters were helpful 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.