- 學位論文
PI-PS-PLLA可分解型三嵌段共聚物之合成與自我組裝研究
Degradable Polyisoprene-b-Polystyrene-b-Poly(L-lactide) Triblock Terpolymers Syntheses and Self-Assembly Studies
摘要
近年來，多嵌段共聚物自我組裝(self-assembly)因微觀相分離(microphase-separation)以形成有序之奈米結構之行為一直是高分子領域中研究的熱門課題，其微觀相分離的原因是藉由不同的鏈段互不相容(immiscible)而相互排斥，因此形成之有序奈米微結構可依不同的體積分率形成不同型態(morphology)。本研究以合成可分解性之多嵌段共聚物為主(e.g., PI-PS-PLLA)，並控制各嵌段體積分率探討其自組裝後所形成之微觀相分離型態。由於合成之三嵌段共聚物含有兩個可分解之嵌段(PI、PLLA)，因此可藉由可分解嵌段之逐一分別裂解，形成特殊之多孔性奈米級材料，其相關研究具新穎性與實用性。 此新型之三嵌段共聚物之合成可藉由陰離子活性聚合反應(Anionic Living Polymerization)聚合PI-PS之雙嵌段共聚物，另外針對PLLA嵌段之合成則可應用活性開環聚合反應加以建構，由於此一新型三嵌段共聚物之合成接利用活性聚合加以建構，分子量分佈都可以加以有效的控制。故在本實驗中，我們利用陰離子活性聚合合成聚合isoprene及styrene單體，最後加入propylene oxide，以合成成末端備OH-官能基之PI-PS，接著將PI-PS-t-OH末端轉換成巨起始劑(macroinitiator)以進行開環聚合反應(ROP)進行鏈成長反應，聚合出PI-b-PS-b-PLLA三嵌段共聚物。所合成之PI-b-PS-b-PLLA則可藉由核磁共振儀(NMR)、小角度X光散射儀(small angle X-ray scattering)及穿透式電子顯微鏡(TEM)的分析探討三嵌段共聚物的結構及其微觀相分離行為。
並列摘要
In this report, we aim to synthesize novel PI-PS-PLLA triblock copolymer, which contains two degradable blocks (namely PI and PLLA blcoks) and which is able to self-organize onto ordered morphologies by self-Assembly. As this unique triblock copolymer can undergo sequential degration of the PI and the PLLA block via difference proceses, novel nanoporous material could be generated using the PI-PS-PLLA triblock copolymers as the potential templates. Two types of living polymerization technologies were used in the synthesis of PI-PS-PLLA triblock copolymer. First, living anionic polymerization technology was used for the sequential polymerization of isoprene and styrene. The resulting living PI-PS block was in situ treated with propylene oxide for proving the hydroxyl-capped PI-PS [PI-PS-CH2CH(CH3)-OH] as the end-functionalized PI-PS diblock copolymer. Second, utilization of the [PI-PS-CH2CH(CH3)-OH] prepolymer to undergo the living ring opening polymerization of L-lactide provide the successful generation of PI-PS-PLLA triblock copolymers with well-defined chemical structure (precise block length control with narrow molecular weight distribution) as revealed by NMR and GPC analyses. Consequently, PI-PS-PLLA triiblock copolymers prepared by our synthetic approach are able toself-organized into consistent nanostructures as evidenced by Small Angle X-ray Scattering studies and Transmission Electron Microscopy analyses.