合成雙親性團聯共聚合物並製備蜂窩狀多孔性薄膜

Abstract

近年來，雙親性團聯共聚物被廣泛地研究及討論，主要是因為其製備方法繁多，同時可利用親疏水鏈段在極性上的差異，形成特殊型態結構。本研究先後以原子轉移自由基聚合法及自由基聚合法，合成聚甲基丙烯環氧丙酯與聚乙烯吡咯烷酮之雙親性團聯共聚合物，再利用此高分子在具有濕氣的環境中製備出高規則、蜂窩狀多孔性高分子薄膜。 實驗中首先將偶氮化合物進行酯化，使末端帶有溴原子而成為雙官能基起始劑，以原子轉移自由基聚合法，利用溴化亞銅/2,2’-聯吡啶形成之錯合物為觸媒系統，於室溫使雙官能基起始劑之末端與單體甲基丙烯環氧丙酯反應，以製備具偶氮基之巨起始劑—聚甲基丙烯環氧丙酯；隨後將此巨起始劑，以自由基聚合法於適當溫度下與單體乙烯吡咯烷酮反應，合成出聚甲基丙烯環氧丙酯與聚乙烯吡咯烷酮之雙親性團聯共聚物，並探討下列三個問題： (1) 利用末端具溴原子之雙官能基起始劑，以原子轉移自由基聚合法合成具偶氮官能基之巨起始劑—聚甲基丙烯環氧丙酯，並討論在不同反應條件下進行聚合，包括：反應溶劑、配位基種類及濃度、反應單體/起始劑之莫耳比例。針對製備條件及反應組成，找出最佳反應參數，以有效控制巨起始劑之分子量及分子量分佈大小，並利用凝膠滲透層析、氫核磁共振光譜、傅立葉轉換紅外線光譜進行分子量測定及結構分析。 (2) 利用具偶氮基之巨起始劑與乙烯吡咯烷酮單體，以自由基聚合法製備聚甲基丙烯環氧丙酯與聚乙烯吡咯烷酮之雙親性團聯共聚物。藉由調整單體與巨起始劑比例，選擇適當溶劑並控制反應溫度、時間，以製備不同鏈段比例及分子量之雙親性團聯共聚物，同樣針對製備條件對共聚高分子之分子量大小、分布，與分子鏈段長度變化的影響加以研究。 (3) 將所合成之雙親性團聯共聚合物溶於適當的溶劑中，在具水氣及風速一定的環境中製備出高規則蜂窩狀之多孔性薄膜，以光學顯微鏡及掃描式電子顯微鏡觀察此高分子薄膜。同時探討此團聯共聚物在不同條件下的型態學與孔洞大小、壁厚的趨勢，並成功地控制此高規則多孔性高分子薄膜之孔洞大小。

Amphiphilic block copolymers have been extensively studied because of the versatile synthetic approaches and the tunable morphology. In this study, block copolymers of glycidyl methacrylate (GMA) and vinyl pyrrolidone (VP) were obtained by the combination of two different free-radical polymerization mechanisms namely atom transfer radical polymerization (ATRP) and conventional free radical polymerization (CFRP). Then the polymer thin film possessing a hexagonal array of micro pores (honeycomb film) could be obtained by solution casting of amphiphilic block copolymers in high vapor solvent under a flow of moist gas. In the first part, thermosensitive azo alky halide, difunctional initiator, was prepared . The obtained bromine ended difunctional initiator was used for ATRP of GMA monomer at room temperature in conjunction with CuBr/2, 2’-bipyridine as a catalyst. In the second part, the azo functional group of poly(glycidyl methacrylate) (PGMA) was used as a macro-initiator in FRP of VP to prepare the amphiphilic block copolymer poly(glycidyl methacrylate-block-vinyl pyrrolidone) (PGMA- b-PVP). The objectives of this thesis are as below: (1) The obtained bromine ended difunctional initiator was used for ATRP of GMA monomer to prepare a macro-initiator at room temperature. Molecular weight distribution of PGMA was optimized through the reaction composition or reaction condition of ATRP, including solvent, monomer/initiator ratio, catalyst and ligand concentrations. Then molecular weight, polymer dispersity index and characterized data of macro-initiators are characterized by gel permeation chromatography (GPC), Fourier transfer infrared spectroscpoy (FT-IR) and proton nuclear magnetic resonance spectrometry (1H-NMR). (2) The macro-initiator (Azo-PGMA) was used for FRP of VP monomer to synthesize poly(glycidyl methacrylate-block-vinyl pyrrolidone) (PGMA-b-PVP). Block copolymer variations of molecular weight of hydrophobic and hydrophilic parts in block copolymer were studied. (3) Finally, a regularly porous honeycomb structured film can be prepared from the suitable solution of the amphiphilic diblock copolymer under moisture air flow. The morphology of the prepared film was observed by optical microscopy (OM) and scanning electron microscope (SEM). The diameter of the spherical pores can be controlled ranging from 2.3 μm to 0.5 μm by the amphiphilic copolymers relative molecular weight as well as by the casting conditions. We propose that most important element in the formation of order structure may be determined on the polymer to precipitate at solution/water interface.