有機-無機黏土與量子點奈米複合材料物理性質之研究

Abstract

高分子複合材料一般為有機高分子基材與無機添加物的結合且至少存在於一維的奈米尺寸的範圍下。添加物從結構上可以分為一維(例如:奈米碳管與纖維)，二維 (片狀的無機材料，如黏土)，與三維 (球與量子點)。導入奈米尺寸添加物高分子上，改善了高分子原本的物理性質。在本篇論文可以分成四個部分，探討無機的添加物對於高分子複合材料物理性質的影響。 1.插層劑側鏈的官能基對於聚苯乙烯/黏土奈米複合材料影響 我們利用三種不同插層劑改質的有機黏土藉由乳化聚合製備聚苯乙烯/黏土奈米複合材料。這些奈米複合材料在黏土含量在3 wt %時皆達到脫層的結構。我們所使用的插層劑( C20、 C20-4VB、與 C20-POSS)經由離子交換反應後成功進入黏土的層間，使親水黏土與疏水高分子有更好的相容性，進一步的讓改質後的有機黏土均勻分散於高分子基材中並達到脫層的結構。從X-ray繞射儀 (XRD)、穿透式電子顯微鏡 (TEM) 與傅立葉紅外線光譜儀 (FT-IR) 的結果指出所使用的插層劑有成功的進入到黏土的層間，並成功製備具有脫層結構的聚苯乙烯/黏土奈米複合材料。在熱性質的測試中 (TGA與TMA)，C20-POSS/黏土聚苯乙烯奈米複合材料相對於聚苯乙烯下開始產生裂解的溫度可以提升25 °C其熱膨脹係數 (CTE) 最大的降低的量可以達到40 %。另外，這些經由改質奈米複合材料的玻璃轉化溫度(Tg)都高於聚苯乙烯。 2.經由POSS的插層劑改質使聚苯乙烯奈米複合材料性質提升 我們使用POSS-NH2與C20-POSS 為插層劑改質黏土並進一步製備POSS/黏土聚苯乙烯奈米複合材料。X-ray 繞射儀 (XRD) 的結果指出本研究所使用的插層劑製備的POSS/黏土奈米複合材料在X-ray的圖譜上都沒有繞射峰出現，此結果表示我們所製備的奈米複合材料皆達到脫層的結構。並進一步從穿透式電子顯微鏡 (TEM) 直接觀察複合材料的結構型態，從結果指出黏土均勻分散於聚苯乙烯高分子基材中並達到脫層的結構。對於C20-POSS/黏土奈米複合材料我們導入這些脫層的黏土於聚苯乙烯中可以有效的提升其玻璃轉化溫度(Tg)、熱裂解溫度 (Td) 與熱膨脹係數 (CTE) 最大的降低的量可以達到40 %。 3.有機奈米黏土在聚氧代氮代苯并環己烷於低表面能材料的影響 我們製備新穎低表面能聚氧代氮代苯并環己烷/有機黏土改質奈米複合材料。我們使用三種液體的方法計算表面能。CPC/黏土 10%/PP-a奈米複合材料經過200 ℃/4小時交聯後反應後具有極低的表面能係數 12.7 mJ/m2，甚至低於我們所熟悉的鐵氟龍材料(22.0 mJ/m2)。我們使用X-ray光電子光譜(XPS)表示我們所製備的奈米複合材料的表面具有較高的矽含量，表示有機黏土在製備的過程中優先的存在於最外層的表面。另外，CPC/黏土 10%/PP-a奈米複合材料的玻璃轉化溫度(Tg)較PP-a高22.6 ℃與熱裂解溫度 (Td)也相對於PP-a提升31.5 ℃。我們發現這個方法可以製備同時具有低表面能與高熱穩定性的高分子黏土奈米複合材料。 4.製備具有刺激-應答硫化鋅/聚異丙基丙烯醯氨中空球 新穎的量子點硫化鋅/聚異丙基丙烯醯氨混成中空球是使用局部自由基聚合反應製備，在PCL奈米球周圍讓異丙基丙烯醯氨與交聯劑 (MBA) 反應所形成，後進一步的使用酵素 (Lipase PS) 將PCL 進行生物分解。我們使用穿透式電子顯微鏡 (TEM)與動態光散射儀 (DLS) 分別有系統的探討所形成的硫化鋅/聚異丙基丙烯醯氨中空球結構與熱敏感可逆的性質。硫化鋅/聚異丙基丙烯醯氨中空球具有螢光的性質並在大約32 oC有膨脹收縮的特性，符合於螢光光譜上有些微紅位移的現象出現。

Polymer nanocomposites are commonly defined as the combination of a polymer matrix and additives that have at least one dimension in nanometer range. The additives can be one-dimensional (example include nanotubes and fibers), two- dimensional (which include layered minerals like clay), or three-dimensional (include spherical particles and quantum dots). Nanoscale-filled polymeric systems offer the prospect of greatly improving many of the properties of the polymer matrix. The dissertation was focused on four major subjects: the study of the inorganic additives of polymer nanocomposites on physical properties. 1.Studies on Thermal Properties of PS Nanocomposites for the Effect of Intercalated Agent with Side Groups Polystyrene layered silicate nanocomposites were prepared from three new organically modified clays by emulsion polymerization method. These nanocomposites were exfoliated up to 3 wt % content of pristine clay relative to the amount of polystyrene (PS). The intercalated agents, C20, C20-4VB, and C20-POSS intercalated into the galleries result in improved compatibility between hydrophobic polymer and hydrophilic clay and facilitate the well dispersion of exfolicated clay in the polymer matrix. Results from X-ray diffraction, TEM and Fourier transform infrared spectroscopy indicate that these intercalated agents are indeed intercalated into the clay galleries successfully and these clay platelets are exfoliated in resultant nanocomposites. Thermal analyses of polystyrene-layered silicate nanocomposites compared with virgin PS indicate that the onset degradation temperature ca. 25 °C increased and the maximum reduction in coefficient of thermal expansion (CTE) is ca. 40 % for the C20-POSS/clay nanocomposite. In addition, the glass transition temperatures of all these nanocomposites are higher than the virgin PS. 2.Properties Enhancement of PS Nanocomposites through the POSS surfactants The polyhedral oligomeric silisesquioxnae (POSS)-clay hybrids of polystyrene are prepared by two organically modified clays using POSS-NH2 and C20-POSS as intercalated agents. X-ray diffraction (XRD) studies show that the formation of these POSS/clay/PS nanocomposites in all cases with the disappearance of the peaks corresponding to the basal spacing of MMT. Transmission electronic spectroscopy (TEM) was used to investigate the morphology of these nanocomposites and indicates that these nanocomposites are comprised of a random dispersion of exfoliated throughout the PS matrix. Incorporation of these exfoliated clay platelets into the PS matrix led to effectively increase in glass transition temperature (Tg), thermal decomposition temperature (Td) and the maximum reduction in coefficient of thermal expansion (CTE) is ca. 40 % for the C20-POSS/clay nanocomposite. 3.Effect of the organically modified Nanoclay on Low-Surface-Energy Materials of Polybenzoxazine Novel low surface free energy materials of polybenzoxazine/organically modified silicate nanocomposites have been prepared and characterized. The CPC (cetylpyridinium chloride)/clay10%/Poly(3-phenyl-3,4-dihydro-2H-1,3-benzoxazine) (PP-a) possesses an extremently low surface free energy (12.7 mJ/m2) after 4 hrs curing at 200 ℃, even lower than that of poly(tetrafluoroethylene) (22.0 mJ/m2) calculated on the basis of the three-liguid geometric method. X-ray photoelectron spectroscopy (XPS) shows higher silicon content on the surface of nanocomposites than average composition, implying that the clay is more preferentially enriched on the outermost layer. In addition, the glass transition temperature (Tg) of the polybenzoxazine (PP-a) in the nanocomposite is 22.6 ℃ higher and its thermal decomposition temperature is also higher than the pure PP-a. This finding provides a simple way to prepare lower surface energy and high thermal stability material. 4.Preparation of the Stimuli-Responsive ZnS/PNIPAM Hollow Spheres Novel quantum dots ZnS/poly(N-isopropylacrylamide) (PNIPAM) hybrid hollow spheres were obtained by localizing free radical polymerization of NIPAM and crosslinker (MBA) at the peripheral of PCL nanoparticles, followed by biodegradation of PCL with an enzyme of the Lipase PS. The formation of ZnS/PNIPAM hollow spherical structures and the thermo-sensitive reversible properties were systematically investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. The ZnS/PNIPAM hollow spheres possess the photoluminescence properties and a swelling and de-swelling at about 32 oC, which agrees well with the slight red-shift in photoluminescence spectra.