超分子型高分子應用於電紡奈米纖維

Abstract

本論文中以開發超分子型高分子材料應用於電紡奈米纖維，內容分為四大主題: 1. 尿嘧啶官能化高分子的仿生光交聯奈米纖維 在本研究中，我們利用電紡技術製備具核鹼基官能化及光致交聯的poly[1-(4-vinylbenzyl uracil)]（PVBU）奈米纖維。高分子量的PVBU（Mn >250 550 g/mol）具有高的熱穩定性和足夠的分子鏈纏結度，以利製備均勻且無珠狀小球的纖維。這些尿嘧啶官能化的奈米纖維可透過照射254奈米波長的紫外光進一步光交聯。在浸漬於溶劑N,N-dimethylacetamide後，原始PVBU纖維溶解，而交聯的PVBU纖維保持其形狀，因此，交聯PVBU奈米纖維表現出良好的尺寸穩定性和提高的耐溶劑性。 2. 仿生超分子纖維對汞離子的吸附 以尿嘧啶官能化高分子poly[1-(4-vinylbenzyl uracil)]（PVBU）為基礎的新光交聯型奈米纖維，利用靜電紡絲技術製備出。PVBU奈米纖維藉由曝照於254奈米波長的紫外光可轉換成共價網絡鍵結的奈米纖維。PVBU奈米纖維能夠區分並選擇性地從含其它金屬離子的水溶液之中除去汞離子（Hg2+）。該PVBU奈米纖維的最大汞離子的吸附量為543.9毫克/克，它比環狀imide衍生物的吸附量顯著更高。 由於汞離子吸附的增加使之偵測極限低於1ppm，這在汞離子偵測中很少能達到。此外，用1.0M HCl還原處理，PVBU纖維可以連續重複使用10個循環。這種新材料可同時偵測和分離汞離子在環境和工業領域中具有顯著的潛力。這種新材料具有顯著的潛力在同時偵測和分離汞離子於環境和工業領域之中。 3. 共軛型電紡奈米纖維的形貌與光學物理性質於氫鍵作用力下的影響 Poly(3-thiophene-triazole-diaminopyridin)（ PTDAP ）的發光奈米纖維經由混合具互補氫鍵鍵結點之主體高分子poly[1-(4-vinylbenzyl uracil)]（ PVBU ）以及對照的主體高分子聚苯乙烯( PS )成功地電紡製備出。從1-50 ％（重量）混合比例電紡出的PTDAP / PVBU纖維其直徑為300-1270奈米與PTDAP / PS纖維相比展現出均勻的形貌和螢光性。當PTDAP的混合比例增加，PTDAP/PS纖維中珠狀結構的纖維和珠狀小球增加，這表示和PVBU相比PTDAP與PS有較差的相容性而導致PTDAP的聚集，且在旋轉塗佈的薄膜也獲得類似的結果。此外，在相同PTDAP的混合比例下PTDAP / PVBU纖維的放光波峰比PTDAP /PS纖維更加藍移，這表示強的氫鍵作用有利於PTDAP與PVBU沿纖維軸延伸從而防止PTDAP的聚集，因此移到更高能量放射。 4. 多層奈米碳管分散於氫鍵系統中的電紡奈米複合纖維之製備與特性 含有共軛高分子poly(3-thiophene-triazole-diaminopyridin)（ PTDAP ）和多層奈米碳管（MWCNTs）的奈米複合纖維藉由與兩個主體高分子，poly[1-(4-vinylbenzyl uracil)]（ PVBU ）具有氫鍵合性官能團和對照的聚苯乙烯（PS）電紡製備出並研究奈米碳管在纖維中的分散與聚集。導電度的結果顯示PVBU / PTDAP / MWCNT纖維比PS / PTDAP / MWCNT纖維能形成低電阻的一個更好的電通路，這表示PVBU主體和PTDAP主體之間的氫鍵相互作用確實幫助多層碳奈米碳管在纖維中的分散。透射電子顯微鏡顯示，多層奈米碳管在PVBU / PTDAP主體之中是高度沿纖維軸的方向。即使高濃度的多層奈米碳管在PVBU / PTDAP / MWCNT纖維中一樣能分散很好，這可以歸因於PTDAP能藉由π-π相互作用連結無官能化的多層奈米碳管表面，防止多層奈米碳管聚集，同時PVBU主體提供了與PTDAP的氫鍵作用力，分散了脫附的多層奈米碳管在電紡過程能整齊排列於高分子主體中。這項研究不僅改善了奈米碳管在電紡奈米纖維中的分散性，同時也示範藉由導入氫鍵作用力設計具有延展和高度對齊多層奈米碳管的複合奈米纖維之可能性。

In this study, we focus on four major subjects which based on supramolecular polymers for application in electrospun nanofibers. 1. Bioinspired Photo-Cross-Linked Nanofibers from Uracil-Functionalized Polymers In this study, we used electrospinning to fabricate nucleobase functionalized and photo-cross-linkable poly[1-(4-vinylbenzyl uracil)] (PVBU) nanofibers. PVBU of high-molecular-weight (Mn > 250 550 g/mol) possessed a high thermal stability and sufficient chain entanglement to produce uniform fibers without forming beads. These uracil-functionalized nanofibers were further photo-cross-linked through exposure to UV light at a wavelength of 254 nm. After immersing in N,N-dimethylacetamide, the pristine PVBU fibers dissolved, while the cross-linked PVBU fibers maintained their shape; thus, the cross-linked PVBU nanofibers exhibited good dimensional stability and improved solvent resistance. 2. Bioinspired Supramolecular Fibers for Mercury Ion Adsorption A novel photo-cross-linkable nanofiber based on a uracil-functionalized polymer, poly[1-(4-vinylbenzyl uracil)] (PVBU), was prepared using the electrospinning technique. This PVBU nanofiber can be converted into a covalent network nanofiber through exposure to UV light at a wavelength of 254 nm. This PVBU nanofiber is able to distinguish and selectively remove mercury ions (Hg2+) from other metal ions in aqueous solution. The maximum Hg2+ adsorption capacity of the PVBU nanofiber is 543.9 mg g-1, which is significantly higher than that of cyclic imide derivatives. The improved adsorption of Hg2+ allows a detection limit of less than 1 ppm, which has rarely been achieved for Hg2+ sensing. Furthermore, the PVBU fiber can be reused for 10 consecutive cycles using 1.0 M HCl treatment. This new material has significant potential for the simultaneous detection and separation of Hg2+ in environmental and industrial fields.

3. The Influence of Hydrogen Bonding Interaction on Morphology and Photophysical Properties of Conjugated Electrospun Nanofibers Light-emitting nanofibers of poly(3-thiophene-triazole-diaminopyridin) (PTDAP) were successfully electrospun through binary blends of two matrix polymers from poly1-(4-vinylbenzyl uracil) (PVBU) which possessed complementary hydrogen bonding sites and compared polystyrene (PS). PTDAP/PVBU blend fibers with diameters of 300-1270 nm electrospun from 1-50 wt% blend ratios show the uniform morphologies and fluorescence in comparison with PTDAP/PS blend fibers. The increases of beaded structure fibers and beads in PTDAP/PS blend fibers as the increase of PTDAP blend ratio indicates that PTDAP has worse misibility with PS than PVBU inducing the aggregation of PTDAP and a similar result is obtained in the spin-coated films. In addition, the emission peaks of PTDAP/PVBU fibers were more blue-shifted than those of PTDAP/PS fibers at the same PTDAP blend ratio which indicates that the strong hydrogen bonding facilitates PTDAP more extending along the fiber axis with PVBU which prevents the aggregation of PTDAP thereby shifting the emission to higher energies.

4. Fabrication and Characterization of Multiwalled Carbon Nanotubes Dispersion to Hydrogen-Bonding System of Electrospun Composite Nanofibers Composite nanofibers containing conjugated polymer, poly(3-thiophene-triazole-diaminopyridin) (PTDAP), and multiwalled carbon nanotubes (MWCNTs) were electrospun with two polymer matrices, poly1-(4-vinylbenzyl uracil) (PVBU) possessing hydrogen bonding functional group and compared polystyrene (PS) and study the dispersion and arrangement of nanotubes in the fibers. The conductivity result showed that PVBU/PTDAP/MWCNT fiber can form a better charged pathway of low resistance than PS/PTDAP/MWCNT fiber, indicating that the hydrogen bonding interaction between PVBU matrix and PTDAP did facilitate the dispersion of MWCNTs in the fibers. Transmission electron microscopy showed that the MWCNTs were highly oriented along the fiber axis in the PVBU/PTDAP matrix. MWCNTs are well dispersed in PVBU/PTDAP/MWCNT fiber even at high concentration which can be attributed that PTDAP can bind to the surface of non-functionalized MWCNTs through π–π interactions, preventing MWCNTs from aggregating, while PVBU matrix provide hydrogen-bonding forces with PTDAP, dispersing the de-bundled MWCNTs aligning in the polymer matrix during electrospinning process. This study not only improves the nanotube dispersion in the electrospun nanofibers but also demonstrates a possibility to design a composite nanofiber with extended and highly aligned MWCNTs by introducing hydrogen bonding forces.