The 1 H NMR spectrum of poly(ethylenimine) (PEI) has been assigned using two-dimensional NMR correlation with the previously established assignment of the 13 C spectrum. The oxidative thermal and UV degradation of PEI has been studied using mass loss measurements, and NMR and Fourier transform infrared spectroscopy. Analysis of the spectra of the degradation products shows that the degradation process may readily be monitored, particularly by 13 C NMR. The major products are formamide and other amide groups which may be understood in terms of chain scission and dehydration reactions of hydroperoxides.

The products and mechanism of the thermal oxidative degradation of poly(ethylene oxide) at 150 °C have been analysed using 13C NMR spectroscopy. The analysis was assisted by the use of distortionless enhancement by polarisation transfer spectra, longitudinal relaxation time measurements, long‐range 13C1H coupling and chemical shift simulation software. The major result of degradation was chain scission resulting in two formate ester chain ends. Minor products were in‐chain esters, peroxy groups, oxymethylene links and hydroxy and methoxy chain ends.

The products and mechanism of the thermal oxidative degradation of poly(ethylene oxide) at 150 °C have been analysed using 1H and 13C 1‐D and 2‐D NMR spectroscopy, including COSY, HMQC, HMBC and DOSY techniques. Peaks from methanoate ester chain ends (in the majority), in‐chain esters, peroxy groups, acetal links and ethanoyl chain ends have been assigned. Two small molecule degradation products, 2‐hydroxyethyl methanoate and ethylene glycol dimethanoate have been identified. Copyright © 2004 Society of Chemical Industry

The products and mechanism of the thermal oxidative degradation at 180 °C and the photo‐oxidative degradation at 40 °C of polytetrahydrofuran have been investigated using 1H NMR, 13C NMR and GPC. The NMR analysis was assisted by the use of DEPT 13C spectra, two‐dimensional NMR spectroscopy (COSY, HMQC and HMBC) and chemical shift simulation software. The NMR spectra of both thermally and photolytically degraded samples were similar showing that the degradation mechanisms were similar. GPC indicated that both chain scission, leading to lower molar mass products, and chain extension, leading to higher molar mass products, occurred initially. NMR analysis of the initial soluble degraded polymers showed that chain scission resulted in formate, aldehyde, propyl ether, butyl ether and propanoyl chain ends, and in‐chain ester groups were also formed. For longer periods of degradation, crosslinked gels were formed but these were not amenable to detailed structural characterisation by high‐resolution NMR to determine the crosslink mechanism. Copyright © 2004 Society of Chemical Industry