Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/3326
標題: Morphology and Crystallization Behavior of Poly(ε-polycaprolactone) in Physically Confinement Environment
物理侷限環境下聚ε己內酯之結晶與形態
作者: 蔣酉旺
Chiang, Yeo-Wan
關鍵字: physical confinement;物理侷限;chemical confinement;localization;化學侷限;局部偏析
出版社: 化學工程學系
摘要: 
本研究首先利用共聚合物微觀相分離(microphase separation)之作用力,促使不互容之摻合系統達到相容(compatibilization)效果。經由熔融摻合(melt blending)的方式,將不同分子量之結晶性材料聚ε己內酯(ε-polycaprolactone, PCL)與具有微觀相分離結構之苯乙烯團聯共聚合物材料polystyrene-b-poly(ethylenepropylene) (PS-PEP)摻合,利用結晶性材料與共聚合物之間物種溶解參數的不同造成彼此物種間之排斥效應,結合共聚合的微觀相分離之驅動效果,而促使原不互容之摻混組成PCL與PS達到相容(compatibilization)效果,形成所謂的團聯共聚合物之自我排組驅動力所誘導之相容系統(block copolymer self-assembly induced compatibilization)。針對此一互容系統PCL/PS-PEP,本實驗利用偏光顯微鏡(polarized light microscopy, PLM)結合穿透式電子顯微鏡(transmission electron microscopy, TEM)之形態觀察以及微差掃瞄熱卡計(differential scanning calorimetry, DSC)所測定之摻混系統的玻璃轉化溫度之變化,配合Fox方程式之理論推算,推論摻混之均聚物PCL將聚集於PS微觀層板間形成不均勻之局部偏析(nonuniformly swelling localization)現象,由於PCL均聚合物與PS-PEP團聯共聚合物間並無化學鍵鍵結的因素存在,所以此混摻系統中PCL的結晶行為乃受限於所謂的物理侷限(physically confinement)。相對於利用可結晶性團聯之共聚合物(crystallizable block copolymers)的化學鍵結方法而自我排組及自我有序形成一微觀相分離系統,以期探討結晶於侷限空間中之發展與熔融行為,即所謂的化學侷限 (chemical confinement),兩者將有所不同。物理侷限系統是將結晶性材料在物理作用力控制下,嵌入一微觀相分離環境中,形成溶解或偏析局部現象而有不同微觀受限尺寸,而結晶性高分子鏈於此微觀受限環境中進行結晶與熔融行為時,排除結晶性共聚合物的鏈端受到化學鍵鍵結的影響,只受到空間侷限及物種間物理的吸引與排斥力影響。
本實驗同時利用小角X光散射(small angle X-ray scattering, SAXS)與廣角X光繞射(wide angle X-ray scattering, WAXD)針對高剪切應力場下所進行之摻合系統分析探討其有序微結構與結晶結構的對應空間幾何關係,發現高剪切應力場可有效的提供一應力場誘導之有序層板微結構取向(orientation),並證實PCL於此有序層板微結構間亦即物理侷限空間作用下,其結晶層板之分子鏈排列方向將具有特定的取向,結晶分子鏈對應有序層板微結構形成晶格b軸平行層板法向量取向之排列方式。而此時PCL晶格之分子鏈方向亦即c軸方向則平行於有序層板微結構表面,換言之PCL結晶結構之折疊排列與有序層板微結構形成一平行折疊模式。
由於物理侷限空間對結晶層板之晶格分子鏈排列方向性的影響,PCL之結晶與熔融行為將呈現相當有趣的變化,在不破壞微觀層板結構之一維侷限空間下,由於侷限空間之阻隔效果反映在結晶速率上,造成PCL分子鏈之結晶成核之擾動碰撞機率比在無侷限效果的情況下要低,使得達到臨界成核尺寸之機率變小,導致其較難去克服成核之能障,因而需要較高程度的過冷效應(undercooling)以克服成核的能障,因此降低了最快結晶速率溫度。對應於單純PCL結晶之熔融行為,由於PCL於侷限空間下之結晶成長為平行受限之有序層板微結構表面,結晶所呈現的熔解溫度則並未有明顯的變化。綜觀上述的結果,高分子的結晶行為在侷限之空間中確實會受到空間的影響而發生相對的變化。

An interesting way to obtaining compatible blends from the blending of poly(ε-caprolactone) (PCL) and polystyrene-b-poly(ethylenepropylene) (PS-PEP) has been achieved. The intrinsically immiscible blend systems such as PCL/PS and PCL/PEP become compatible while the PS and PEP form copolymer to melt blending with PCL. Taking advantage of the driving force of self-assembly for block copolymers, the PCL component appears to be localized in-between the lamellar microdomains of PS-PEP. The blend systems, PCL/PS-PEP, are found to self-assemble as ordered micorstructures of multiple lamellar-layers with tens of nanometer dimension. The morphology of PCL/PS-PEP blends is examined by polarized light microscopy (PLM) and transmission electron microscopy (TEM). The results of compatibility are investigated in terms of differential scanning calorimetry (DSC). Contrary to typical microphase-separated morphology of crystallizable block copolymers (designated as chemically confined environment for crystallizing blocks), we name this unique phase-separated morphology as physically confined environment for PCL.
URI: http://hdl.handle.net/11455/3326
Appears in Collections:化學工程學系所

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