SYNTHESIS AND POLYMERIZATION OF T-BOC PROTECTED MALEIMIDE MONOMERS - N-(T-BUTYLOXYCARBONYLOXY) MALEIMIDE AND N-[P-(T-BUTYLOXYCARBONYLOXY) PHENYL]-MALEIMIDE

Two t-butyloxycarbonyl (t-BOC) protected maleimide monomers, N-(t-buty loxycarbonyloxy)maleimide (t-BOCOMI) and N-[p-(t-butyloxycarbonyloxy)p henyl]maleimide (t-BOCOPMI), have been synthesized and polymerized. Th e t-BOC group was used to protect the hydroxy groups of the starting N -substituted maleimides, N-hydroxymaleimide (HOMI) and N-(p-hydroxyphe nyl)maleimide (HOPMI). t-BOCOMI and t-BOCOPMI were copolymerized with styrene derivatives (X-St) to obtain the t-BOC protected polymers P(t- BOCOMI/X-St) and P(t-BOCOPMI/X-St) in high conversions. P(t-BOCOMI/St) and P(t-BOCOPMI/St) were cleanly deprotected by heating the polymers to 110 and 175 degrees C, respectively. The deprotection temperature o f the copolymers of t-BOCOMI (ca. 100 degrees C) is the lowest among t he known t-BOC protected polymers. Deprotection of P(t-BOCOMI/X-St) an d P(t-BOCOPMI/X-St) produced the corresponding polymers having HOMI an d HOPMI structures, respectively, and resulted in large changes in phy sical properties. The deprotected polymers have very high glass transi tion temperatures (above 250 degrees C) and good solubility in aqueous base solutions, whereas the t-BOC polymers are only soluble in organi c solvents. P(t-BOCOMI/St) was found to have desirably low ultra-viole t absorption and high sensitivity in resist formulations.