低介電聚酯醯亞胺/官能基修飾介孔二氧化矽複合材料之製備、鑑定及其於高頻材料之應用研究

Synthesis, characterization and physical property studies of low dielectric poly(ester imide) / functionalized mesoporous silica composites and their application in high-frequency materials

陳冠穎(Kuan-Ying Chen)

指導教授 ： 葉瑞銘

中原大學/理學院/化學研究所/博士(2019年)

https://doi.org/10.6840/cycu201900657

摘要

本研究論文的研究主軸為製備同時具低介電常數(dielectric constant, Dk)及低介電損失(dielectric loss, Df)之非氟系之聚酯醯亞胺/介孔二氧化矽複合材料薄膜，內容共分為三個部分論述。
首先，第一部分為有機高分子之製備，使用二胺單體ODA (4,4'-oxydianiline)及APAB (4-aminophenyl-4-aminobenzoate)和二酸酐單體BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride)及TAHQ (p-Phenylene bis(trimellitate) dianhydride)以相異比例進行預聚合，合成四種高分子後，分別塗佈於銅箔再以高溫熱縮合方式進行環化閉環，爾後將銅箔蝕刻，即可獲得一系列之聚酯醯亞胺(poly(ester imide))薄膜。此部分主要探討於聚醯亞胺主結構中，引入酯類官能基，製備成聚酯醯亞胺後，其高頻之電性變化。 文獻報導中指出，聚酯醯亞胺比聚醯亞胺有較低之吸濕性及膨脹係數，且由於酯類官能基的氧，可與苯環上的氫形成分子間氫鍵，使其高分子排列較為有序具有半結晶(semi-crystalline)之特性，當物質具有結晶形態時，由於結構堆疊整齊緊密，因此介電損失數值較低，但目前尚未有文獻，探討聚酯醯亞胺於高頻頻率(10 GHz)下之介電數值。由實驗結果證實，隨著酯類官能基團引入高分子結構中越多，結晶現象亦隨之明顯，於相同頻率之下，介電損失隨結晶性越高有下降之趨勢，因此在第一部份，選用具較低介電損失之聚酯醯亞胺做為薄膜的基材，此部分並使用FTIR進行結構鑑定，並使contact angle、TGA、DMA及TMA儀器，針對膜材之親疏水性質、熱性質、機械性質進行研究探討。
第二部分為製備具疏水性質且高比表面積之介孔二氧化矽粉體(Mesoporous silica powder)，使用胺基矽氧烷、甲基矽氧烷及四乙基矽氧烷(Tetraethoxysilane, TEOS)，利用溶膠-凝膠法進行無機粉體之合成，並使用非界面活性劑作為孔洞材料之模板，水洗移除後即可獲得官能化介孔二氧化矽無機粉體。 材料設計分兩類，首先探討使用三種胺基含量修飾介孔二氧化矽粉體之差異，胺基矽氧烷作為修飾孔洞材料之目的為，預期藉由胺基與有機高分子之酸酐官能基團，形成化學鍵結，使無機相於有機相中具有良好之分散性，但胺基為吸水官能基團，胺基含量過多將造成材料吸水率上升，影響介電性質，因此須調控最適胺基比例進行合成。 第二類為使用適當胺基比例，並使用疏水性甲基矽氧烷修飾介孔二氧化矽粉體，並調整成孔模板比例，對無機孔洞材料進行疏水性改質及比表面積與平均孔徑大小之調控。 由實驗結果得知，經由甲基矽氧烷修飾之介孔二氧化矽粉體，疏水性值大幅提升，且使用越多非界面活性劑成孔模板，所得之介孔二氧化矽粉體具有較高之比表面積及平均孔洞直徑。本部分使用FTIR、Solid Satte NMR進行結構鑑定，使用BET對孔洞材料之比表面積及平均孔洞直徑進行探討，最後使用contact angle及TGA針對親疏水性質及熱性質進行分析。
第三部分，將第一部分具最低介電數值之聚酯醯亞胺導入第二部分所製備之一系列親/疏水介孔二氧化矽粉體，分別製備成有機無機複合材料，因文獻中指出將介孔材料導入有機高分子製備成複合材料時，可將空氣導入材料，進而降低整體材料之介電常數。共分三小節探討。 首先聚酯醯亞胺與三種相異比例胺基修飾介孔二氧化矽粉體，針對分散性、吸濕性及介電性質進行討論，經由TEM證實，胺基比例越多，有機/無機分散相越好，但其吸濕性亦有上升之趨勢，且具有較高之介電數值；接著使用兩種相異比表面積之疏水官能基修飾二氧化矽粉體，針對粉體比表面積的多寡，對介電數值造成影響進行探討。由實驗結果得知，當粉體於同一重量比例下，導入高分子製備成複合材料，比表面積較高的粉體所製備之複材，具有較低之介電常數與介電損失；最後將探討具高比表面積之疏水介孔二氧化矽，使用四種相異重量百分比例，導入聚酯醯亞胺製備成複合材料後之介電性質變化。由實驗結果得知，隨著疏水介孔二氧化矽粉體的比例越高，所製備之複合材料之介電常數有逐漸降低之趨勢，目前導入最高比例粉體之複材，其於10 GHz頻率條件之下，介電常數可從原本未加粉體之3.27降為2.93，介電損失從原本未加粉體之0.007小幅上升至0.009，影響介電常數之數值推測為，加入疏水介孔二氧化矽粉體，可有效降低吸濕性及導入空氣，但導入粉體的同時，從XRD光譜結果得知，隨著粉體導入比例提升，結晶性亦隨之下降，推測此一結果導致介電損失數值進而提升。此外本部分之實驗，使用contact angle及TGA對材料吸濕性進行探討，另外使用DMA、TMA及拉伸試驗對複合材料之熱性質及機械性質，進行研究探討。

關鍵字

聚酯醯亞胺 ； 介孔二氧化矽 ； 溶膠-凝膠法 ； 高頻 ； 低介電 ； 結晶性 ； 疏水

並列摘要

The aim of this research is to prepare a non-fluorinated poly(ester imide)/mesoporous silica composite film with low dielectric constant (Dk) and low dielectric loss (Df).
The experimental design was divided into three parts. The first part is the preparation of organic polymer using diamine monomer ODA (4,4'-oxydianiline) and APAB (4-aminophenyl-4-aminobenzoate); and dianhydride monomer BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride and TAHQ (p-Phenylene bis(trimellitate) dianhydride). The monomers were polymerized in varying proportions to synthesize four different polymers, which were then used to coat the copper foil. The ring closure was carried out through high-temperature thermal condensation, and the copper foil was etched to obtain a series of poly(ester imide) films. The introduction of ester functional group to the polyimide structure resulted to high-frequency electrical changes in the polyester quinone imine. Previous literatures have reported that poly(ester imide) has lower hygroscopicity and expansion coefficient than pristine polyimide due to the presence of oxygen in the ester functional group, allowing the formation of intermolecular H-bond with the hydrogen on the benzene ring. In addition, the ester-functionalized polyimide has a relatively more ordered structural arrangement and possesses semi-crystalline characteristics. When the material has a crystalline form, the dielectric loss is low due to the tightly packed structure, but no existing literatures have studied this property for poly(ester imide) in high frequency conditions. This study confirmed by experimental results that the more ester functional groups are introduced into the polymer structure, crystallization phenomenon becomes more apparent. Dielectric value at high frequency (10 GHz). Under the same frequency, the dielectric loss decreased with the higher the crystallinity. For this part, the lower dielectric loss of polyester bismuth imide was selected as the substrate of the film. The structure of the synthesized material was characterized through FTIR, and used contact angle, TGA, DMA and TMA instruments to target the hydrophobicity of the film.
The second part focused on the preparation of mesoporous silica powder with hydrophobic properties and high specific surface area, using amino siloxane, methyl siloxane and tetraethoxysilane (TEOS). The sol-gel method was used to synthesize the inorganic powder, and the non-surfactant was used as a template for the pore material, while the functionalized mesoporous silica inorganic powder was obtained by washing with water. Two types of material design were used. First, the mesoporous silica powder was modified by three kinds of amine groups, in order to functionalize it with amine oxime, based on the anhydride functional group of amine group and organic polymer. The group forms a chemical bond making the inorganic phase to have good dispersibility in the organic phase, yet the presence of excess water-absorbing amine groups affects the dielectric properties of the material. Thus, it is critical to optimize amount of the amine groups present in the material. The second type used a suitable ratio of amine groups, to modify the mesoporous silica powder with hydrophobic methyl siloxane, and adjust the ratio of pore template to modify hydrophobicity and the specific surface area and average pore diameter of the inorganic pore material were regulated. Based from experimental results, the hydrophobicity value of the mesoporous silica powder modified by methyl siloxane was greatly improved. In addition, the more non-surfactant pore-forming template was used, the higher the specific surface area and average hole diameter of the mesoporous silica powder. In this part, FTIR and solid-state NMR were used for structural identification. The specific surface area and average pore diameter of the pore material were investigated by BET. Finally, the contact hydrophobicity and thermal properties were analyzed using contact angle and TGA.
In the third part, the poly(ester imide) with the lowest dielectric value obtained from the first part, was introduced into the second part to prepare a series of hydrophilic/hydrophobic mesoporous silica powders, which were prepared into organic-inorganic composite materials, as indicated in the literature. When a mesoporous material is introduced into an organic polymer to prepare a composite material, air can be introduced into the material, thereby lowering the dielectric constant of the overall material. This part was further divided into three sections. First, poly(ester imide) and three different ratios of amine-modified mesoporous silica powders were studied for dispersibility, hygroscopicity and dielectric properties. It was confirmed by TEM that the more amine groups were present, the better the phase of the organic/inorganic dispersion. However, increased hygroscopicity was observed, which led to higher dielectric values. Thus, the impact of dielectric values was explored by modifying cerum oxide powder with two hydrophobic functional groups with different specific surface areas. It was observed that when the powder was formed into a composite material at the same weight ratio, the obtained composite material with the powder having a higher specific surface area, has a lower dielectric constant and dielectric loss. The hydrophobic mesoporous silica with high specific surface area was then further investigated, and the dielectric properties of the composite material was prepared by introducing polyester bismuthimide using four different weight percentages. It was found from the experimental results that as the proportion of the hydrophobic mesoporous silica powder became higher, the dielectric constant of the prepared composite material gradually decreased. Currently, the highest proportion of the powder was introduced into the composite material at 10 GHz. Under this frequency condition, the dielectric constant was reduced from 3.27 to 2.93; and the dielectric loss was increased from 0.007 to 0.009, which was similar to the pristine powder. The value of the dielectric constant was estimated through the addition of hydrophobic mesopores. The cerium oxide powder can effectively reduce the hygroscopicity and introduce air. However, as the amount of introduced powder was increased, the crystallinity consequently decreased, as seen from XRD experiments. This phenomenon is presumed to be attributed to the increased dielectric loss. The contact angle and TGA were used to investigate the hygroscopicity of the materials. In addition, DMA, TMA and tensile tests were used to study the thermal and mechanical properties of the composites.

並列關鍵字

Poly(ester imide) ； Mesoporous silica ； Sol-gel ； High frequency ； Low dielectric ； Crystalline ； Hydrophobic

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