p-[Bi~(trimethylsilyl)methyllisopropenylbenzene (BSIB) was prepared by reaction of a,pdimethylstyrene (DMST) with lithium diisopropylamide (LDA) and trimethylsilyl chloride (TMSCI). Anionic polymerization of BSIB with sec-butyllithium (BuLi) or living lithium a-methylstyrene oligomers at -50 OC in THF gave polymers with the predicted molecular weights and narrow molecular weight distributions. When the temperature of the polymerization mixture was increased up to 20 "C after the monomer was almost completely consumed, the polymer formed disappeamd almost completely, indicating the anionic polymerization of BSIB to be a living equilibrium system. The ceiling temperature of BSIB in the anionic polymerization was 1.2 f 0.9 "C,
To induce degradabilities in polymers in response to environmental conditions, endmodification reactions of poly(a-methylstyrene) (PMS) derivatives were carried out. 2-Phenylallyl halide derivatives such as 2-phenylallyl bromide, 2-@-tolyl)allyl bromide, and a-trifluoromethylstyrene were found to be suitable end-modification agents. For example, the o-2-phenylallyl-PMS derivative was prepared with almost quantitative functionali1.y by the reaction of the living PMS derivative with 2-phenylallyl bromide. In a similar way, o3,3-difluoro-2-phenylallyl-and o-2-(4-tolyl)allyl-PMS derivatives were synthesized. Based on thermogravimetric analysis, the onset of the degradation temperature of the endmodified PMS derivatives decreased in the following order: o-hydrogen-> w-3,3-difluoro-2-phenylallyl-> o-2-phenylallyl-> o-2-@-tolyl)allyl-PMS. Actually, the onset temperature of w-2-@-tolyl)allyl-PMS derivatives was 50 "C lower than that of o-H-PMS derivatives. These results indicate that the active species is produced effectively at the endunsaturated bond, which initiates depolymerization of the polymer at rather low temperatures. Therefore, it is concluded that a 2-phenylallyl substituent at the end of the PMS chain induces effective degradation through a radical mechanism.
Several types of poly(si1amine)s were prepared and their structure-characteristics relationships were investigated. When a phenyl ring in the organosilyl unit and/or a cyclic structure in the amino unit was introduced, the glass transition temperatures were increased significantly in order to increase film formability. From the thermogravimetric analysis of the poly(silamine)s, it was found that the thermal decomposition of poly(si1amine)s starts at ca. 380-400°C. On electron-beam irradiation of the poly(si1amine) films, degradation of the polymer took place. On the basis of these results, poly(si1amine)s can be one of the candidates for new positive-type polymeric resists.
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