| Summary: | 碩士 === 國立成功大學 === 化學工程學系 === 104 === The thiol di-terminal homopolystyrene was synthesized by anionic polymerization by using t-BuLi/1,3-DIB as the diintiator and ethylene sufite as the termaination agent. Following, the thiol di-terminal homopolystyrene was further initated by living polymerization of methyl methacrylate (MMA) with initiator pair, di-terminal thiol group and caprolactam, to prepare triblock copolymers, poly(methyl methacrylate)m – block- (polystyrene)n- block- poly(methyl methacrylate)m With replacing styrene monomer by isoprene, the preparation of triblock copolymer could also proceed by the new initiator pair, and the poly(methyl methacrylate)m – block-(polyisoprene)n-block-poly(methyl methacrylate)m triblock copolymers (MIM) were successfully synthesized with this novel approach. The termination functionalization of poly(isopryl)lithium with thiiranes were characterized by 1H, 13C NMR spectroscopy, and MALDI-TOF mass spectrometry. The result of MALDI-TOF mass spectrometry indicates that reaction was seriously influenced by polar solvent, such as THF. The thiol terminal group did not obtain when THF was presented in reaction medium.
On the other hand, the different size chain and different configuration structures of thiol chain-end-functionalized polyisoprenes was synthesized and further react with equal weight of MMA in different apolar solvents. Lesser the molecular weight of thiol chain-end-functionalized polyisoprene was, faster the rate of reactions with methy metharylate was. Furthermore, 1,4-addition of polyisorene has better reactivity with MMA by using mercaptan/ε-caprolactam living polymerization than that of 3,4-addition. In addition, xylenes was more suitable to act as the solvent than toluene and benzene due to the differnet steric effect and polarity. Two glass transition temperature (Tg), including PMMA and PI domains, of MIM was presented on the curves of DSC measurement. The lower Tg is attributed from PI domain, which is not serious influenced by PMMA chain and vice versa, because the PMMA and PI domains are not missible. This result can be further proved by the phase separation diagram of AFM and TEM micrographs.
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