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. PCl3, PBr3, P2S5, and H3PO4 + P2O5 were examined, and it was noticed that PCl3 and PBr3 were the most effective phosphorylating reagents. The best results for the phosphorylation process of poly(vinylcarbazole) were obtained at 76°C when PCl3 was used and at 140°C when PBr3 was used. It was confirmed that the percentage of phosphorus which was introduced into the polymer can be expressed by the following formula: The optimal value of the reaction time for both these phosphorylating reagents PCl3 and PBr3 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.