MASS-SPECTRAL CHARACTERIZATION OF LINEAR AND CYCLIC FORMS OF OLIGOMERIC NITRATED POLYETHERS BY ELECTROSPRAY-IONIZATION - SPECIFIC CATIONIZATION EFFECTS IN CYCLIC POLYETHERS

Electrospray ionization mass spectrometry provides a highly detailed p icture of the various species present in the high energy material poly (3-nitratomethyl-3-methyloxetane), also known as polynimmo. Polynimmo contains up to 18 cyclic oligomers in addition to the dominant tetrame r, the highest species detected containing 22 repeat units. Linear oli gomers from the tetramer up to species of mass 3200 Da are detected, a ffording the characterization of several new combinations of end group s X, Y in X-[nimmo](n)-Y. Various cations can be used to generate the cationized species, and highly specific cation-cyclic oligomer interac tions are apparent in the adducts with Na+, K+, NH4+ and H+: some of t hese can be rationalized through molecular modelling calculations. The cone voltage applied In the e.s.i. experiment is highly significant i n influencing the relative abundances of high- and low-molecular mass ions and in the relative amounts of H+ and NH4+ adducts in cationizati on experiments with NH4Cl. Despite giving highly accurate relative mol ar masses of individual species within polynimmo, the e.s.i. technique fails to give accurate molecular mass distributions, especially as no doubly- or triply-charged ions are found. Crown copyright (C) 1997 Pu blished by Elsevier Science Ltd.