Multifunctional finishing of cotton fabrics with 3,3',4,4'-benzophenone tetracarboxylic dianhydride: reaction mechanism.

Aqueous solutions of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BPTCD) were successfully employed in treatment of cotton fabrics to bring multiple functions onto the cotton cellulose. The overall reaction mechanism of the chemical finishing process was investigated. Results revealed that the dianhydride groups of BPTCD were hydrolyzed to tetracarboxylic acid groups, and the acid could directly react with hydroxyl groups on cellulose under the catalyst sodium hypophosphite to form ester bonds. Such a mechanism is different from the mostly recognized formation of anhydride from polycarboxylic acid and then esterification between the anhydride with hydroxyl groups. FTIR, DSC and thermogravimetric analyzer (TGA) were employed in the analysis of the reactions, respectively.