posted on 2021-09-01, 14:38authored byMax Born, Konstantin Karaghiosoff, Thomas M. Klapötke
In the field of energetic
binders, only hydroxy-terminated glycidyl
azide polymer (GAP) has found widespread application and prevailed
in the market. However, oxiranes such as glycidyl azide (GA) allow
two ring-opening modes during polymerization and thus lead to polymers
of different termination causing inhomogeneous curing results. An
elegant solution is the polymerization of 3-azidooxetane as only terminating
primary hydroxyl groups are formed. Beyond this, poly(3-azidooxetane)
and GAP are equal in other aspects due to the similar repetition
unit. Since literature methods for the preparation of 3-azidooxetane
either employed toxic solvents, gave low yields or impurified product,
or could not be reproduced, a new synthesis method was developed to
afford pure material and satisfying yields. The syntheses of toluene-
and methanesulfonic acid esters of oxetan-3-ol as precursors were
also significantly improved in comparison to the literature and their
molecular structures elucidated by single-crystal X-ray diffraction.
The aforementioned compounds and poly(3-azidooxetane) were intensively
studied by vibrational and multinuclear NMR spectroscopy (1H, 13C, 14N), differential scanning calorimetry,
and elemental analysis. The key compound, 3-azidooxetane, was compared
to glycidyl azide regarding performance using the EXPLO5 V6.04 thermochemical
code and their sensitivity toward external stimuli like shock and
friction assessed according to BAM standard procedures.