• 學位論文

Nanohybrid Thin Films from Degradable Block Copolymer Templates

Nanohybrid thin films have been wildly exploited as the devices in the applications of nanotechnologies. The inorganic-organic hybrid materials are the candidates for next-generation materials owning to their excellent material properties, such as optical, electrical, optoelectronic, mechanical, and magnetic properties. Diblock copolymers with degradable segment can be used for topographic nanopatterning through hydrolytic treatment. Sol-gel chemistry is a well-known method to synthesize various ceramic oxide compounds which has a wild range of applications. In this study, we aim to use the topographic nanopatterns as templates for the sol-gel reaction so as to fabricate Nanohybrid thin films. Polystyrene-b-poly(L-lactide) (PS-PLLA) thin films with well-oriented, perpendicular PLLA hexagonal cylinders can be prepared by spin coating. Degradable PLLA microdomains were degenerated by hydrolytic process so as to create nanoporous PS thin films (i.e., topographic nanopatterns) with well-defined cylindrical nanochannels. By taking advantage of the nanoreactor concept, the sol-gel reaction for the fabrication of inorganic oxides can be achieved via templating so as to create PS/SiO2 nanohybrid thin films. To acquire successful templating for the sol-gel reaction, it is necessary to carry out the pore-filling process for introducing the inorganic oxide precursors into the template. Different methods have been designed and examined in order to achieve the optimized condition for the successful templating through pore-filling. The topographic nanopatterns were floated on the sol-gel solution (i.e., the mixture of TEOS, methanol and aqueous HCl solution) with the participation of small amount of water to enhance the surface tension of the solution. However, water causes the formation of large SiO2 particles before pore-filling. Subsequently, instead of direct pore-filling of the sol-gel solution with water, the nanoporous thin films were collected on Cu grid, and then the pore-filling process of the sol-gel solution followed by the sol-gel reaction using the vapor of water was carried out. The formation of templated SiO2 could be identified, suggesting that the solution was successfully driven into the nanopores by capillary force. Similar process for templated sol-gel reaction can be conducted by pore-filling the mixture of TEOS and methanol solution but without the HCl aqueous solution. Subsequently, the pore-filled template was exposed to the vapor of aqueous HCl solution. Significant improvement on the pore-filling efficiency could be achieved through this method due to the occurrence of the sol-gel reaction after pore-filling. To acquire the best efficiency of templated sol-gel reaction, the reaction rate of sol-gel process should be justified so as to alleviate the formation of SiO2 before pore-filling. Alternatively, a low-temperature process for the sol-gel reaction was used such that giving the well-defined PS/SiO2 nanohybrid thin films with high pore-filled efficiency. Consequently, well-ordered nanorods can be obtained after the degeneration of PS by UV exposure. Apart from the formation of PS/SiO2 thin films, PS/TiO2 thin film can also be prepared by similar approach. As a result, we demonstrate an easy method for the formation of nanohybrid thin films by combining the templating of nanoporous thin films resulting from degradable block copolymers and the sol-gel reaction within templates.

• 學位論文

可分解性聚酯嵌段共聚物之合成與自組裝行為之研究

The chiral effect on the self-assembly of block copolymers has been demonstrated for a block copolymer system containing chiral entities (i.e. a chiral block copolymer (BCP*)), poly(styrene)-b-poly(L-lactide) (PS-PLLA BCPs*), and it leads to the formation of new phases such as helical phase (H*). To comprehend the effect of chirality on BCP self-assembly, a series of poly(4-vinyl pyridine)-b-poly(L-lactide) (P4VP-PLLA) BCPs* were synthesized. Similar to the PS-PLLA, a helical phase can be found in the self-assembly of the P4VP-PLLA BCPs*. Also, we aim to investigate the mechanisms of chiral information transfer from molecular level to macroscopic level through self-assembly. P4VP-PDLA BCPs* were synthesized for self-assembly so as to compare the self-assembling results of P4VP-PLLA. Vibration circular dichroism (VCD) spectroscopy was used to examine the handedness of helical chain conformation. The results indicated that the P4VP-PLLA and P4VP-PDLA BCPs* possess left- and right-handed helical chain conformations, respectively. A red shift in the circular dichroism (CD) spectra of BCPs* chains in solution reflected the occurrence of aggregation so as to lead the formation of helical superstructures. It is intuitive to suggest that one-handed superstructures can be obtained from the self-assembly through chiral information transfer. Interestingly, right-handed helical superstructures were found from the self-assembly of P4VP-containing BCPs* in solution regardless of enanitomeric character. As a result, the chiral information might be missing as the BCPs* self-assemble into higher organizational levels; namely, the chiral information transfer can not be successfully achieved. To truly examine the self-assembly mechanisms and the corresponding morphological evolution, in particular, the issue with respect to handedness control, the self-assembly processes were controlled by changing the self-assembly conditions such as temperature or solvent. With the appropriate conditions for self-assembly, the formation of left-handed helical superstructures can be achieved from the self-assembly of P4VP-containing BCPs* in solution. For nanopatterning, a series of diblock copolymers, poly(styrene)-b- poly(3-hydroxybutyrate) (PS-PHB), with PHB hexagonal cylinder (HC) nanostructures were synthesized in this study. Well-oriented, perpendicular PHB cylinders of PS-PHB thin films were efficiently achieved by spin coating using appropriate solvents regardless of the use of substrates. After hydrolysis of PHB, well-oriented HC nanochannel arrays over large area in addition to uniform surface with controlled thickness and domain size can be obtained; providing a simple and efficient path to prepare nanopatterned templates for applications. The induced orientation of PS-PHB microdomains is strongly dependent upon the evaporation rate of solvent and its solubility between constituted blocks. Consistent with our previous studies, the primary concern of controlled morphology for nanopatterning is to develop ordered microphase-separated morphology by considering the time scale for segregation, namely segregation strength during solvent evaporation. The induced orientation is attributed to the permeation discrepancy between phase-separated microdomains. The lower Tg for PHB as compared to PLLA provides a much easier way for nanopatterning due to the alleviation of the thin-layer PLLA forming on the substrate so that it is possible to acquire the well-defined nanopatterns under ambient conditions. The perpendicular morphology is initiated from the air surface, and formed in order to create an optimized condition (i.e. the fastest path) for solvent evaporation whereas parallel morphology may impede the evaporation of solvent molecules. Following the microphase separation, the perpendicular morphology can be kinetically induced by solvent evaporation.

• 學位論文

雙層淋幕式塗佈之分析

在現今工業上，多相塗佈製程已是不可或缺的重要製程之一，本研究以淋幕式塗佈為實驗系統探討微粒子添加入甘油水溶液後，塗佈行為的變化，並研究雙層淋幕式塗佈在不同參數下塗佈之行為。單層淋幕式塗佈實驗結果顯示，添加微粒子於甘油水溶液中，可以有助於降低最小成膜流量和穩定動態濕潤線，抑制空氣滲入，提高最大塗佈速度，且粒子濃度越高，粒徑越小延後空氣滲入的效果越好。雙層淋幕式塗佈實驗發現，透過攜帶層的幫助，可以提高上層塗液的最大塗佈速度，且攜帶層中粒子的含量越高，越有助於提升上層塗液的最大塗佈速度，再透過改變上下層的黏度比以及攜帶層的流量等參數，發現改變攜帶層的流量對上層塗液的最大塗佈速度並不會造成影響，而利用較低黏度的攜帶層則會有助於提升上層的最大塗佈速度，且上下層間的黏度會存在一最佳黏度比，如果上下層黏度相差太大，則會造成淋幕的不穩。

• 學位論文

Fabrication of Metal Grid on Silicon-Based Solar Cell by Electrochemical Deposition and Microcontact Print

This work presents a novel and low-cost printing technique to construct a three-layer (Pd/Ni/Cu) structure as front-side conductor of textured mono-crystalline silicon solar cells. The technique involves microcontact printing and electrochemical deposition. Electrochemical deposition including electroless Ni and electroplated Cu offers an inexpensive method in contrast to the conventional silver-paste. The first step of this technique was activation by Pd nanoparticles. The Pd nanoparticles with average particle size about 2.65 nm were then mixed with organic solvent to prepare Pd ink. Then we imprinted Pd ink on the front side of solar cell by microcontact printing, which could print fine-lines of less than 60 μm width. The second layer is electroless nickel providing low contact resistance and good mechanical adhesion. The third layer is electrodeposited Cu to increase the line conductivity. X-ray Diffraction (XRD) technique, Secondary Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) were employed to detect the presence of nickel-silicides phase and the thickness of nickel-silicides phase after annealing. Moreover, the depth profile of metal contact was determined by Secondary Ion Mass Spectrometry (SIMS) and Electron probe X-ray Microanalyzer (EPMA). Finally, the line conductivity of three layer structure is lower than silver paste, and this new scheme has proven to be workable and may become an alternative approach for surface metallization on solar cell.

• 學位論文

以奈米碳管經由濕式塗佈方式製備透明導電膜之分析

本論文研究以濕式塗佈製作透明導電膜，主要材料為具有許多優異特性之材料—奈米碳管。奈米碳管不論是在機械、熱傳及電學特性上都有廣泛的研究及多功能的應用。在透明導電膜上的應用，可使用濕式塗佈製程，塗佈於可撓性基板且不需在高溫下操作，使生產成本降到最低。 研究共分為兩個部份，第一個部份是探討利用表面張力梯度形成的表面張力效應，建立出中間薄、周圍厚的類蜂巢結構，使透明導電膜達到高導電率及高穿透率的性質。實驗共使用三種溶劑系統，分別是去離子水、甲苯及酒精，觀察各系統在乾燥過程的現象並探討塗佈參數的影響，得到當溫差大、溼膜厚、黏度小、溶劑揮發性高者，容易產生類蜂巢結構，在本研究中，當溶劑系統為甲苯及酒精時，易產生毫米等級的類蜂巢結構。 第二個部份直接使用奈米碳管塗佈透明導電膜，調整各實驗參數以建立奈米碳管的塗佈視窗，並尋找適當的乾燥溫度、溼膜厚度等製程參數，測量各種透明導電膜之關鍵特性，如穿透率、電阻、均勻度及黏著性等等，待製程參數等條件確立後，比較不同塗佈方式對透明導電膜的影響，並結合塗佈產品的特性，進而找出最佳的塗佈方式及條件。最後將各製程之參數以無因次群—雷諾數表示，並找出雷諾數與透明導電膜之穿透率、電阻等特性之關係，得到當雷諾數越大，塗佈之透明導電膜的穿透率與電阻皆會下降的結果。

• 學位論文

適用含有機/無機微奈米粒子懸浮塗液系統於濕式塗佈製程之精密模具設計

塗佈產品如燈箱片、LCD擴散膜、CIGS薄膜太陽能電池、TCO透明導電膜等，其濕式製程所用之塗液皆為含有微奈米固體粒子之多相系統，以此類系統進行濕式塗佈工程時常面臨兩個問題：一是懸浮液系統可能含有屈伏應力，可能造成塗液於模具內流動緩慢或滯留，二是塗液中所含的固體粒子在塗佈模具內發生沉澱的現象。實驗結果顯示模具之分流管越大，粒子在分流管內的沉澱就越嚴重；反之若模具分流管內之流場具有較大之切變率則可改善此問題。本研究之目的為設計一衣架型模具，其分流管為一極淺的矩形，如此可維持模具內之流動維持高切變率。為了改善衣架型模具製作費用昂貴的缺點，本研究提出了組合式模具之設計概念。 本研究內容分為理論模擬與實驗驗證兩部分：理論部分先以巨觀一維之滑潤理論設計模具形狀，再配合有限元素法來模擬模具內二維(2-D Hele-Shaw flow)和三維之流動情況，出口流量分佈及所產生之滯留區，塗液之流變行為假設遵守Bingham 模型。理論模擬之結果顯示以滑潤理論設計之衣架型模具能夠傳遞均勻的液膜且模具內亦無明顯之滯留區存在，模具之幾何形狀具有彈性，可隨著不同之操作流體而做調整，T型模具由於分流管較大故在末端有滯留區的產生，此區域容易發生粒子沉澱之現象。實驗部分以常用之T型模具和魚尾型模具作為對照組，探討流量均勻度和粒子沉澱兩個議題，結果證實本研究所設計之模具能成功解決粒子沉澱之問題且塗膜之均勻度亦非常優越，相對而言T型模具和魚尾型模具則分別具有粒子沉澱和模具尺寸受限制等問題。本研究結果可作為銅銦鎵硒(copper indium gallium selenide, CIGS)太陽能電池與透明導電膜(transparent conductive oxide, TCO)等產品於濕式製程之模具設計參考。

• 學位論文

摻雜過渡金屬之觸媒在光催化及加氫脫硫反應促進效應之研究

本研究中探討了摻雜過渡金屬的促進效應對於觸媒在光催化以及深度加氫脫硫反應之影響。在光催化反應上，以溶膠凝膠法及共沉澱法製備含鋯之二氧化鈦光觸媒，探討不同鍛燒溫度及鋯添加量的效應；在深度加氫脫硫反應中，則以共沉澱法製備出含釩之氧化鋁載體，含浸鈷及鉬做為深度加氫脫硫反應中之活性物質，並觀察不同釩添加量對反應轉化率及脫硫效率的影響。在觸媒特性鑑定上，則分析了摻雜過渡金屬後的觸媒其晶型結構、比表面積與孔洞特性、表面的元素組成及元素間的相對比例。 實驗結果顯示，在光催化反應中，以溶膠凝膠法製備之鋯含量為10 mol%與鍛燒溫度為500 ℃之鈦鋯混合金屬氧化物對乙醛反應進料有最佳的光催化效果，藉由使用Langmuir-Hinshelwood動力學模型，可求得模型中的參數值，並配合觸媒之鑑定結果，得到參數值與觸媒特性間相對關係的經驗式；在深度加氫脫硫反應中，含釩的氧化鋁觸媒其反應路徑傾向於氫化後脫硫而非直接脫硫，有助於移除結構阻礙程度較高的硫份化合物4,6二甲基二苯並噻吩。此外，使用傳統氧化鋁觸媒與含釩的氧化鋁觸媒經磨碎混合後的混合觸媒，可達到較佳的轉化率以及較高的脫硫效率，而達到降低柴油中硫份的效果。

• 學位論文

Semiflexible Polymers with Specific Interactions

This dissertation centers on the self-organization behavior of semiflexible polymers bearing specific interaction groups to form special aggregates or supramolecular assemblies with themselves or another macromolecule with complementary binding groups. The systems studied include (1) semiflexible conjugated polymers (bearing pi-pi interaction groups) for opto-electronic applications and (2) DNA (bearing anionic phosphate groups) capable of forming electrostatic complexes with cationic dendrimers for mimicking DNA-histone complexation and for applications as non-viral vectors for gene therapy. For the study of conjugated polymers, we focused on the conformational and aggregate structures and phase separation-induced gelation of poly(9,9-dioctylfluorene) (PF8) and poly(3-hexylthiophene) (P3HT) in the solutions with relatively poor solvents. Using small angle neutron scattering (SANS), PF8 in toluene was found to display wormlike chain conformation in dilute toluene solution. The effective Kuhn length of the chain increased with increasing polymer concentration due to excluded volume interaction. In the semidilute regime, the polymer formed transient networks in which the sub-chains constituting the dynamic meshes were essentially rodlike. The originally viscous liquid solution transformed into a gel when the semidilute solution was aged at -20 oC. The gel composed of a PF8-enriched phase and an isotropic phase due to the occurrence of a macrophase separation at the subambient temperature. The PF8-enriched phase was mesomorphic, consisting of sheetlike aggregates or membranes with thickness of ca. 2.6 nm. A fraction of the PF8 chains or segments within these sheetlike aggregates formed the beta-phase which dominated the photoluminescence of the gel. The mechanism of phase separation-induced gelation of PF8 was further investigated using the solution of PF8 with a poor solvent methylcyclohexane (MCH), as this system underwent gelation easily at room temperature and would hence allow the phase separation process to be conveniently monitored in situ. Light scattering and optical microscopy revealed that the gelation was driven by a macrophase separation occurred through a spinodal decomposition mechanism. Although the spinodal decomposition could proceed to the late stage, the interconnected morphology was arrested to give rise to the gel property. Like the toluene gel, the phase-separated MCH gel also composed of an isotropic phase and a PF8-enriched liquid crystalline phase, in which a fraction of PF8 chains formed the beta-phase embedded within the loose membranes. The MCH gel exhibited a better thermal stability than the toluene gel, and the thermally-induced gel-to-sol transition was accompanied with the disruptions of the loose membranes and the beta-phase that led to homogenization of the solution. In contrast to PF8 systems, the gelation of the solution of P3HT with xylene occurred through a liquid-solid phase separation. Here we have demonstrated the use of small angle X-ray scattering (SAXS) to identify the formation of nanowhiskers in the P3HT gel. We have shown that the P3HT chains originally forming network aggregates in xylene solution underwent crystallization to yield the nanowhiskers. The networking of the nanowhikers may lead to gelation of the solution. In contrast to the highly crystalline nanowhiskers formed in dilute P3HT solutions, the whiskers in the gel showed relatively low crystallinity due to the strong inter-chain interaction of P3HT in the network aggregates that restricted the registry and organization of a fraction of chains into the crystallites. The integrity of the nanowhiskers was largely maintained by the crystallinity of P3HT; therefore, the nanowhisker morphology was disrupted upon heating to the melting point of P3HT crystallites. For the study of DNA-dendrimer complexes (called “dendriplexes”), we focused on resolving the supramolecular structures of the complexes with the 4th generation (G4) polyamidoamine (PAMAM) dendrimer. Using synchrotron SAXS and scattering function calculation of model structures via Debye equation, we showed that, depending on the charge density of the dendrimer prescribed by its degree of protonation (dp), the dendriplexes exhibited three distinct nanostructures characterized by different degrees of DNA twist. At dp < 0.3 the dendriplex displayed a columnar mesophase in which the square-packed DNA bridged by dendrimer showed relatively extended conformation. Increasing dendrimer dp to 0.3 induced a moderate twist of DNA into superhelices organized in a hexagonal lattice. At dp ≥ 0.6 where the interior tertiary amine groups were protonated, DNA wrapped around the dendrimer by 1.4 turns and penetrated into the dendrimer interior as the electrostatic attraction well dominated its bending energy.

• 學位論文

Morphological Diagram of the Electrostatic complexes of DNA with PAMAM G4 Dendrimer

Abstract Cationic dendrimers are a potential nonviral vector for gene therapy because of their ability to form electrostatic dendriplexes with DNA as well as their lack of immunogenicity. The structure of the dendriplexes can influence their interactions with cells and hence the transfection efficiency; however, the supramolecular structure of DNA-dendrimer complexes formed under different conditions and its impact on cellular uptake and gene transfection efficiency remain to be explored in detail. Using small angle X-ray scattering, here we show that DNA in the complexes with poly(amidoamine) (PAMAM) G4 dendrimer exhibited four distinct packaging states modulated by the charge density of the dendrimer prescribed by its average degree of protonation (dp, the average number fraction of protonated amine groups in dendrimer). However, we also discuss the effect of charge ratio of the dendriplexes. On this side, we find that decreasing the charge ratio of the dendriplexes affects as increasing the charge density of dendrimer, which means the four distinct packing structures also show up when varying the charge ratio of the dendriplexes. In addition, we also discussed the isotope effect of the dendriplexes. Overall, the various the charge density and charge ratio indeed alter the conformation of the dendriplexes, and we also build a the morphological map of the dendriplexes along two coordinates: charge density of dendrimer” and the “charge ratio” for understanding the effect of these two variations clearly.

• 學位論文

研發新頴核酸載體平台於調控基因表現與抑制之應用

天然細胞外間質(extracellular matrices, ECM)已廣泛應用於組織工程與再生醫學。在市售的ECM之中，以豬體中取出的小腸黏膜組織下層(small intestinal submucosa, SIS)對於燒燙傷修補和組織重建具有明顯療效。由於SIS中含有負電之醣胺素分子，故本研究藉由靜電作用力讓帶正電之核酸傳遞載體(polymer/DNA奈米複合體)吸附於SIS上，將SIS與核酸傳遞結合以作為調控基因表現之平台。當奈米複合體與細胞接觸時，可將所包覆之DNA攜帶入細胞中，進行特定基因表現。以生醫材料平台調控基因傳遞至標的細胞，具有專一性且可以大幅提升基因傳遞效率，不管是組織工程或疾病治療均可使用這個平台。平台建立後，需要與低毒性之高分子核酸傳遞載體結合。本研究藉由現今已廣泛應用於組織工程之聚(酯-胺基甲酸酯) (poly(ester urethane), PEU)與聚乙二醇(poly(ethylene glycol), PEG)合成出生物可分解性、毒性低且溶於水之聚(胺基-酯-乙二醇-胺基甲酸酯) (poly(amino-ester-glycol-urethane), PaEGU)，其可與核酸物質自組裝成高度專一性帶且正電之PaEGU/DNA或PaEGU/siRNA奈米複合體，使核酸傳遞入細胞中並抵擋生物體內酵素將其分解，亦可將大幅提升核酸傳遞效率。以建立新穎核酸傳遞之平台，應用於組織工程或疾病治療。