Copolymers from tert-butyl methacrylate and itaconic anhydride––reactivity ratios and polymer analogous reactions

Free radical copolymerisation of tert-butyl methacrylate (1) and itaconic anhydride (2) has been investigated and reactivity ratios r1=0.272±0.08 and r2=0.301±0.09 have been obtained. Peak temperature of the endotherm and the enthalpy of the cis-elimination of the tert-butyl ester show a linear dependence on the content of anhydride in the copolymer. Alcoholysis of the anhydride with methanol resulted in complete formation of monomethyl itaconate, whereas the reaction with isopropanol in the presence of N,N-dimethyl-aminopyridine as catalyst stopped at lower conversion. Re-formation of the anhydride takes place around 100 °C in case of the monoisopropyl itaconate and at 120 °C for the monomethyl ester. This offers the possibility to adjust polymer properties, e.g. glass transition temperatures and solubility by controlled polymer analogous reaction. The copolymers can be used in photoresist processing, where adhesion and solubility can be adjusted during processing by alcoholysis and baking steps.