Dimethyl sulfoxide (DMSO), a polar liquid of low volatility, was
used as solvent in the synthesis
of branched glycidyl azide polymer (GAP) which is a potential energetic
binder for rocket
propellants. Branched GAP product was purified by an extraction
method using dichloromethane
to create an organic phase and a mixture of methanol−brine (50:50 in
weight) as the extracting
solution. The extraction was carried out in four steps, leaving
only less than 1% DMSO in the
purified branched GAP. The DMSO concentration remaining in the
organic phase was deduced
from the 1H NMR spectra taken after each extraction step.
Finally, the physical performance
of branched GAP was evaluated through the tensile properties, the glass
transition temperature,
and the thermal degradation of the energetic polyurethanes obtained
after curing branched GAP
with different isocyanate compounds. The effect of residual DMSO
in branched GAP on the
tensile properties of polyurethanes was also investigated.