AbstractThe modification reaction of poly(vinyl alcohol) with diethyl chlorophosphate and ethyl dichlorophosphate is studied in homogeneous phase using tertiary amines as catalysts. The structure of the modified polymers was determined by means of1H and31P{1H} nuclear magnetic resonance (NMR) spectroscopy as well as by chemical analysis. The structure of the polymers resulting from the reaction with diethyl chlorophosphate greatly depends on the reaction temperature as well as the catalyst. For lower reaction temperatures (≤25°C) only acyclic phosphate ester groups were observed. The activation energy was found to be 24,9 kJ/mol. The presence of cyclic phosphate ester groups was found, when higher reaction temperatures (>25°C) were used. These results can be interpreted considering the existence of transesterification reactions. Crosslinking structures were obtained in case ethyl dichlorophosphate was used instead of diethyl chlorophosph