Rather than polymer material, I suggest to find a compatible/miscible polymer matrix and an antioxidant which can get the effect you are looking for.

Try coupling it with polysiloxanes.

try polyethylene oxide, you can play with the PEO/Chitosan ratio, aging experiment can be performed to find the suitable ratio

Dear Tulus,

you can try PCL (polycaprolactone) as a blend for Chitosan and vary your ratio for your desired longivity you are looking for.

with regards,

polysiloxane or phenolic compounds

Dear Dr Tulus,

you can try adding carboxymethyl cellulose and vary the ratio.

with regards,