The process of hydrolysis of both aspirin and the title copolymer was studied by fluorescence spectra. Our results showed that a large variation of rate of hydrolysis may occur when aspirin is immobilized to a polymer support.By comparing the fluorescence spectra and hydrolysis rate of both aspirin and methyl salicylate

it can be concluded that in a sequence of reactions from copolymer to salicylic acid

the acetyl group of the copolymer is first cleaved

and then followed by the cleavage ester link with the formation of salicylic acid.