可摻雜之電活性聚亞醯胺薄膜、微米球及奈米纖維之製備與性質探討

Preparation and Properties of Dopable Electroactive Polyimide Membranes、Microspheres and Nanofibers

卓育賢(Yu-Sian Jhuo)

指導教授 ： 葉瑞銘

中原大學/理學院/化學研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100457

摘要

本論文中利用氧化偶合一步法合成穩定的半氧化半還原態之胺基封端苯胺三聚體 (Amine-capped aniline trimer；ACAT)，並選為製備聚亞醯胺之雙胺單體，與非共平面之二酸酐 [4,4’-(4,4’-Isopropylidene-diphenoxy)bis (phthalic anhydride)，BSAA] 合成電活性聚亞醯胺 (Electroactive Polyimide，EPI)，由於EPI擁有電活性鏈段和聚亞醯胺的結構，故預期會結合兩者的優點如ACAT的氧化還原和可摻雜特性及聚亞醯胺本質上的高耐熱特性及強機械性質；基於以上幾點，本研究以EPI為原料利用不同方法製備出不同表面型態的成品，共分三種： (1) 薄膜 (EPI) (2) 微米球 (EPS) (3) 奈米纖維 (EPF)，並依其特性應用於不同領域。
　　在薄膜系統中，是利用鑄模法製備出電活性聚亞醯胺緻密自由立膜 (Electroactive Polyimide Membranes，EPI)，並製備出非電活性聚亞醯胺 (NEPI) 及聚苯胺 (PANI) 薄膜三者做比較，發現EPI的氧氮氣體分離能力為13.54，分別較NEPI和PANI高1.96和1.54倍，且經1.0 M鹽酸摻雜後更進一步提升了到16.63；而在熱性質及機械性質方面也比NEPI和PANI還要好。
　　在微米球系統中，利用電噴灑技術製備出電活性聚亞醯胺微米球 (Electroactive Polyimide Spheres，EPS)，並應用在維生素C (AA) 感測器，藉由調控其電噴灑溶液濃度來改變EPS的大小製備出小顆 (EPSS-Small，EPSS) 和大顆 (EPS-Large，EPSL) 的粒子，並和EPI薄膜比較其對AA的電催氧化能力，發現粒徑最小的EPSS修飾電極電催化氧化能力分別比EPI薄膜和EPSL修飾電極高3倍和1.5倍。
　　在奈米纖維系統，則是利用電紡絲技術製備出可摻雜的多孔型電活性聚亞醯胺奈米纖維膜 (Electroactive Polyimide Nanofibers，EPF)，EPF同時擁有電化學氧化還原及可逆摻雜特性，且因為奈米級的多孔型結構讓表面積大幅提升，使得EPF對鹽酸氣體和氨氣有更好的化學傳感靈敏度。
　　最後，聚亞醯胺奈米纖維的電活性及摻雜能力可利用改變二胺單體ACAT的比例來調控，製備出EPF及其共聚物 (ECPF) 和非電活性聚亞醯胺 (NEPF)；因為EPF的連續粗糙表面可提升材料表面疏水效果，再加上其可摻雜的特性，在經過全碳氟酸 (perfluoro- octanesulfonic acid，PFOS) 摻雜後，降低其表面位能，使其接觸角從133º提升至超疏水的155º，有趣的是，經過氨氣的逆摻雜，EPF可以從超疏水切換為超親水。

關鍵字

電活性 ； 聚亞醯胺 ； 氣體分離 ； 電噴灑 ； 感測器 ； 電紡絲 ； 超疏水

並列摘要

In this study, we combine the amine-capped aniline trimer (ACAT) and 4,4’-(4,4’-Isopropylidene-diphenoxy)bis(phthalic anhydride) (BSAA) to prepare the Electroactive Polyimide (EPI), because EPI have electroacitve segment and imide structure, it is expected to integrate these advantages, such as ACAT redox and dopable properties and the nature of the polyimide of high heat resistance and strong mechanical properties, base on the above, we prepare EPI by various method to fabricate : (1) Membranes (2) Microspheres (3) Nanofibers, and applied in different field.
　　In the membrane system, using casting method to prepare electroactive polyimide membranes (EPI), which revealing advanced gas separation capability as well as mechanically and thermally enhanced properties. Polyaniline (PANI) and conventional non-electroactive PI (NEPI) membranes were also prepared for control experiments.
　　It should be noted that EPI membrane were found to reveal permselectivities () of O2/N2  13.54, which is ~1.96 and ~ 1.54-fold higher than that of NEPI and PANI, respectively, based on the investigation of gas permeability analysis (GPA). Upon doping with 1.0 M HCl, the pemselectivities of EPI for O2/N2 was found to be further increased to  16.63. Moreover, significant mechanically and thermally enhanced properties of as-prepared EPI membrane was also found as compared to that of NEPI and PANI membranes based on the studies of dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively.
　　In the microsphere system, electroactive polyimide microspheres (EPS) was successfully prepared by electrospraying technology and applied in the detection of ascorbic acid (AA). The particle size of EPS can be controlled by varying the concentration of spraying solution while the electrocatalysis oxidation properties can be influenced by the different particle sizes of EPS. A sensor constructed using EPSS (small particles)-modified electrode was found to show 3-fold and 1.3-fold higher electrocatalytic activity toward the oxidation of AA than those constructed using EPI thin film and EPSL (large particles), respectively.
　　In the nanofiber system, we have developed dopable porous electroactive polyimide nanofiber (EPF) non-woven mats by electrospun technology. The EPF shows both electrochemical redox activity and reversible dopability, simultaneously. The high surface area, small diameter, and porous nature of EPF give significantly better performance in sensitivity for chemical sensing of HCl or NH3 gas.
　　Finally, degree of electrochemical activity and dopable property can be tuned by varying the content of ACAT existed in as-prepared electro-spun EPF mats. After doping with perfluorooctanesulfonic acid (PFOS), water contact angle of EPF surface is increased from hydrophobicity of 133º to superhydrophobicity of 155º. It is interesting that the EPF mat undergoes a switchable process from superhydrophobicity to superhydrophilicity via doping with PFOS and de-doping with ammonium gas.

並列關鍵字

gas separation ； electroactive ； polyimide ； superhydrophobic ； sensor ； electrospraying ； electrospinning

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