2-Phenylallyl-ended poly

Synthesis of 2-Phenylallyl-ended Poly(a-methylstyrene). Synthesis of poly(a-methylstyrene) having an end double bond was described in our previous papers(15,16). Briefly, to the reactor (100 mL flask equipped with three-way stopcock), THF (6.6 mL), sec-butyllithium (0.34 mL 0.26 mmol) and a-methylstyrene (1.18 g 10 mmol) were added in this order via a syringe at -78 C. The color of the mixture turned brownish red immediately. The reaction was allowed to continue for 20 min. For an end-modification reaction, a 2-5 times excess molar amount of the end coupling agent, 2-phenylallyl bromide, was added to the living polymer solution and allowed to react for 20 min. The resulting mixture was analyzed by GPC and then poured into a large excess of methanol. The precipitate was purified by three successive reprecipitations from THF solution into methanol. The obtained polymer was freeze-dried with benzene to remove the solvents employed. Yield of the polymer was ca. 95%. 

Phenylallyl-ended Poly(a-methylstyrene) as Positive B-Resist... 

Fig. 8 Thermogravimetric analysis of 2-phenylallyl-ended poly(a-methylstyrene) (solid line) and hydrogen-ended poly(a -methylstyrene) (dotted line)...

The depolymerization mechanism from the polymer end has been recently revisited in the design of positive electron beam resists. 2-Phenylallyl-termi-nated poly(a-methylstyrene) was prepared by living anionic polymerization, which exhibited a significantly lower depolymerization temperature on TGA than the H-terminated counterpart [340]. The 2-phenylallyl-terminated polymer depolymerized completely when treated with n-BuLi in THF at room temperature. A single-component resist (without PAG) formulated with the 2-phenylallyl-terminated poly(a-methylstyrene) demonstrated a higher e-beam sensitivity (500 pC/cm2 at 20 keV) than the one based on the H-terminated polymer when developed with methanol/methyl isobutyl ketone (2/3 vol/vol) [340]. However, the sensitivity of the non-catalyzed single-component system... 

Another type of cationic initiation procedure starting from an unsaturated compound has been proposed 49). 3-Phenylallyl bromide is reacted in THF solution with AgSbF6 whereby a poly-THF macromonomer bearing a styryl residue at the chain end is formed ... 

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