Chemical modification of poly(N‐vinylcarbazole)

Investigation of the phosphorylation reaction of poly(vinylcarbazole) was carried out using different phosphorylating reagents and in the presence of various catalysts. PCl 3 , PBr 3 , P 2 S 5 , and H 3 PO 4 + P 2 O 5 were examined, and it was noticed that PCl 3 and PBr 3 were the most effective phosphorylating reagents. The best results for the phosphorylation process of poly(vinylcarbazole) were obtained at 76°C when PCl 3 was used and at 140°C when PBr 3 was used. It was confirmed that the percentage of phosphorus which was introduced into the polymer can be expressed by the following formula:\documentclass{article}\pagestyle{empty}\begin{document}$ \%{\rm P} = 7.35\sqrt[5]{t}. $\end{document}The optimal value of the reaction time for both these phosphorylating reagents PCl 3 and PBr 3 amounts to 6 hr. The phosphorylated poly(vinylcarbazole) obtained under these conditions shows ion exchange behavior—the value of ion‐exchange capacity amounts 3.2 mval/g. The pH‐metric titration curve indicates two stages of dissociation. The DTA curve shows that there is no decomposition of the phosphorylated poly(vinylcarbazole) up to a temperature of 300°C; at 550°C, there is 37.5% loss of weight. Spectrophotometric IR studies of phosphorylated poly(vinylcarbazole) indicate that the maximal quantity of phosphorus in the polymer is 11.3% P, that means one phosphone group in each monomer unit.