先進奈米結構有機-無機混成複合材料(I)

Abstract

我研究團隊是世界第一個發展出非含氟、非含矽類的新一代低表面能材料。同時，本研究 團隊亦擁有「Top-down」(蝕刻)技術與「Bottom-up」(自組裝)技術。於此計畫中，我們欲結合此 兩種強而有力的技術來達到製備先進奈米結構有機-無機混成複合材料，希冀對現今各應用領 域有所助益。 (I) 有機-無機奈米結構設計: 早期大多使用有機(如界面活性劑)與無機(如玻璃纖維、礦物、 黏土等)混成物加入高分子基材中，來改善材料性質。而近五年，本研究團隊於最小的奈米結 構(約1 nm)多面體聚矽氧烷(POSS)已有一些成果與經驗累積，我們提出了解決這類奈米結構 與高分子基材的相容性問題，因而論文受到重視與受邀撰寫專書章節。基於此，我們接下來 計畫中將著重於製備一連串的有機-無機混成共聚材料，並以官能基化之多面體聚矽氧烷為 主，來更進一步克服高分子材料本身的低韌性(Low-Stiffness)和低強度(Low-strength)缺點，是 製備前瞻奈米複合材料相當重要的一個方向，其材料性質可因加入不同之物質而有很大的改 變，此技術將有機會能應用於光學、電學、力學、低介電性、光阻劑與生化等多方面材料， 更能符合產業界創新的需求，仍由於結合了有機高分子的可加工性與無機材料的強度、硬度、 尺寸安定性等優異的性質。 (II) 低表面能材料製備及應用: 我研究團隊是世界第一個發展出非含氟、非含矽類的新一代 低表面能材料，聚氧代氮代苯並環己烷(Polybenzoxazine)，我們提出了利用高分子的分子間與 分子內作用力來改變表面能，為一嶄新的方向，相關研究仍屬少見。在我們研究計畫中將利 用分子間與分子內作用力(氫鍵)來開發新穎低表面能高分子材料，甚至低於市面上泛用的低 表面能材料鐵氟龍。在此部份中，我研究團隊欲延伸近來的研究，更進一步的導入氟與矽原 子於其化學結構中，製備一系列的低表面能材料。而在1995年，Prof. Steven Y. Chou發展了奈 米壓印技術(Nanoimprint lithography) (NIL)，主要優點在於能夠簡單製造sub-25nm的微結構， 且又擁有高產能、低成本和節省時間等多項優點，而欲用來做奈米壓印之母模脫劑之要件為 熱膨脹係數小、玻璃轉移溫度低、抗蝕刻能力佳、壓力縮減係數低、脫模性質佳；其中，在 壓印的過程光阻在於母模上的沾黏是最嚴重的問題，於此領域中十分缺乏化學與材料背景的 研究學者切入。因此，本研究團隊性質極佳的新穎聚氧代氮代苯並環己烷之低表面能材料與 奈米壓印領域的結合更彰顯其重要性；另外，我研究團隊開發之低表面能材料，亦可同時做 為低介電常數材料、表面塗佈材料、自潔材料、抗腐蝕材料、奈米壓印母模脫模劑及染料噴 嘴改質。(III) 以奈米結構材料製備層級式圖樣: 我們亦為世界上首先開創把壓克力鋅鹽單體製備成 奈米纖維(Nanofiber)的研究團隊，並在第三十屆高分子年會中引起廣大的迴響，此奈米結構 材料將可做為奈米反應器(Nano-reactor)來製備純度極高的硫化鋅或氧化鋅量子點(Quantum dots)，為一非常重要的發現；然而，此一維空間的自組裝機制尚有待進一步深入探討。基於 此，計畫中除了將探討奈米纖維一維空間的自組裝機制外，我們同時設計了不同金屬鹽類(e.g. Cd, Fe, Ni…)，以此奈米反應器來製備量子點。而本研究團隊另外擁有的「Bottom-up」(自組裝) 技術為從團狀共聚物(Block copolymer)之精準合成(Anionic, ATRP or TEMPO polymerizations) 到其自組裝(Self-assembly)，近來團狀共聚物的自組裝研究已從兩段式(AB diblock)延伸到三段 式(ABC triblock)的探討，不論於固態或液態中，此材料從合成技術到自組裝後的奈米微結構 都極為複雜與多樣化，而其自組裝後的規則結構有應用於薄膜、微影蝕刻、光子晶體、生物 感測器…等的潛力；而近年來我研究團隊亦對於高分子作用力有另一境界的體會，因此，我 們將結合我研究團隊的多項專長，精準合成一系列含強高分子作用力的兩段式團狀共聚物為 基材，兩兩進行錯合(Complexion)自組裝，來達到三段式團狀物所呈現之多樣性奈米結構。另 外，我們亦利用互補鹼基對(A 與T 或G 與C)分子間本身有很強之氫鍵作用力的概念(作用力 常數約104~105)，進行精準合成高分子，進行多點氫鍵之高分子自組裝，欲建立互補鹼基對 分子間氫鍵作用力於固態及溶液態時之自組裝及型態表現。最後，本研究團隊結合 「Top-down」(蝕刻)技術與「Bottom-up」(自組裝)技術，於矽晶圓上藉由團狀共聚物的自組裝來製 備大面積高度規則之奈米結構圖像。 近年來，奈米材料科學已進入結合各領域的進程，但離實際應用面仍有一段眾多關卡的路 要走。縱觀上述，我們所提之計畫為一務實、具國際競爭力及前瞻的一個整合性研究計畫， 所謂『春江水暖鴨先知』，若我們研究團隊有幸獲青得睞，除了有信心完成所提內容外，更願 意善用我們優秀的研究人才，如鴨子般地保持原有的敏度並耕耘與開拓相關的知識領域，冀 望對提升國內研究環境有所貢獻。

We are the first team in the world to develop a new class of low surface energy materials without containing fluorine or silicon. We also possess extensively both 「Top-down」 (lithography) and 「Bottom-up」 (self-assembly) technologies. In this project, we intend to combine these two fantastic approaches to explore and develop new advanced materials with nanostructural organic/inorganic hybrids possessing potential applications in numerous fields. (I) Design of nanostructural silsesquioxane (POSS) hybrids: Our goals are to prepare a series of inorganic-organic hybrid copolymers involving POSS, the smallest polymerizable inorganic moiety of 1 nm, through various precision copolymerization methods to develop high performance polymeric nanocomposites for optoelectronic, low k materials, next generation photoresist, fabrication of nanoparticles stabilized via functionalized POSS molecules, and defense applications. The incorporation of POSS nanocages into polymeric materials often results in significant improvements in polymer properties, including increases in use temperature, and mechanical properties, as well as reductions in flammability and heat evolution. In our previous studies and invited book review, additionally, discovered significant thermal properties increase through hydrogen bonding interaction. As a result, we will synthesize different functional groups based on POSS moiety to obtain high performance nanomaterials in this part. (II) Low surface energy materials: We were the first one to discover the very low surface energy phenomena in cured polybenzoxazine surface through an appropriate curing temperature and curing time. The surface energy of this polybenzoxazine is even lower than the Teflon. Through detailed studies of morphologies and surface compositions, we understand why the polybenzoxazine surfaces possessing such low surface energy property. In this project, we would like to design a series of fluorinated polybenzoxazine by the ring-opening copolymerization of benzoxazine monomers. The thermal stability also is expected to be improved upon fluorination. This monomer, synthesized by a non-conventional route is a potential precursor for a polybenzoxazine in electronic applications, low flammability, low refractive index, low coefficient of friction and high glass transition temperature. The polybenzoxazine copolymer also can provide low dielectric constant suitable for semiconductor industrial applications. Now we would like to further extend our studies as coating materials for applications in areas such as self-cleaning, corrosion protection, anti-cloggy inorganic nanoparticles, nanoimprint lithography, and inkjet nozzle. (III) Fabrication of nanopatterns: Block copolymer lithography refers to the use of these ordered structures in the form of thin films as nanopatterning templates which has potential applications in areas of nanostructured membranes, lithography, photonic crystals, and others. In order to realize these applications, control over micro domain spatial and orientational order is paramount. We will start from the preparation of a series of diblock copolymers by using anionic polymerization or controlled free radical polymerizations. As a result, we can choose different well-defined nanostructures in comparisons with bulk state, such as nanosphere, nanotube, honeycomb structure (application in photonics), and superhydrophobic surface. We are the first one in the world to prepare the zinc metal-salt (Zn(MA)2) nanofibers. However, the detailed mechanisms such as why the Zn(MA)2 monomer can self-assemble into the well-defined 1D nanostructure is still unclear. To prepare different inorganic nanoparticles/polymer composites by other monomers such as Cd(MA)2, Fe(MA)2, or Ni(MA)2 etc still remain unknown. Importantly, this research plan is also concerned with the fact that most self-assembly behaviors in solution and bulk states. The synthesis of ABC triblock copolymers is relatively more complex; however, the mixture of A-B with C-D diblock copolymers through non-covalent bond interaction between B and C blocks is an easier approach to explore its morphological behavior. The intermolecular association equilibrium constant between A and T, or G and C functional groups in DNA double helical structure is ca. 104~105, which is significantly larger than commercial polymers via hydrogen bonding interaction. The intermolecular hydrogen bonding interactions exist between A and T functional groups. Therefore, we can prepare the supramolecular structures via incorporating these functional groups into commercial polymers. Finally, we will combine the 「Top-down」 and 「Bottom-up」 methods to nanostructural fabrication on wafer surface through block copolymers to establish domains with defect-free periodic patterns over arbitrarily large areas with lithographically. In summary, I would like to emphasize that is proposed project is truly well-planned, world-class, and highly advanced nanotechnologies. Our team members have long established record in related areas and we have full confidence to carry out successfully most of our proposed projects mentioned if we have the opportunity to get approval.