Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 3. Poly‐β‐propiolacton, poly‐β‐pivalolacton und poly‐δ‐valerolacton

Poly(oxycarbonylethylene) (poly‐β‐propiolactone), poly(oxycarbonyl‐1,1‐dimeothylethylene) (poly‐β‐pivalolactone), and poly(oxycarbonyltetramethylene) (poly‐δ‐valerolactone) were pyrolyzed directly in the ion source of a mass spectrometer and their thermal and electron impact induced degradation mechanisms are established. Poly‐β‐propiolactone is thermally degraded by rupture of the OCH2‐bond by a cis elimination to give carboxyl and acryloyl endgroups, whereas poly‐δ‐valerolactone depolymerizes to δ‐valerolactone. Poly‐β‐pivalolactone degrades thermally to cyclic oligomers of pivalolactone, which could be proved by a separated pyrolysis and IR‐spectroscopy and gel chromatography.