Direct Amination of Polyethylene by Metal-Free Reaction

Using recently developed alkane C-H amination chemistry, a mild postmodification. of polyethylene (PE) to form C-N grafts without using a metal catalyst is reported. This method applies N-hydroxyphthalimide (NHPI) as an organic catalyst to cleave C-H bonds to generate a carbon radical that reacts with the N=N of dialkyl azodicarboxylates to form a hydrazine unit. The amination of linear PE was successfully conducted with bis(2,2,2-trichloroethyl)azodicarboxylate (BTCEAD) and di-tert-butyl azodicarboxylate (DBAD) in the presence of NHPI in tetrachloroethane at 110 degrees C. Both BTCEAD and DBAD units have been introduced into PE chains. By optimizing the conditions, like time and feed ratio, the number of grafted BTCEAD units can reach about 10 per 100 ethylene units. Moreover, the DBAD units of PE may be transformed into hydrazine units by treating with trifluoroacetic acid (TFA). The PE modified by BTCEAD and DBAD grafts was blended with poly(methyl methacrylate) (PMMA) and the compatibility was greatly improved. Direct modification of a PE membrane by treating with a solution was also successful.