【作者】 李阳；

【导师】 赵建青；

【作者基本信息】 华南理工大学 ， 材料学， 2016， 博士

【摘要】 聚酰亚胺(PI)是一种应用范围广、用量大的高性能工程塑料,集高耐热性能(初始热分解温度500°C以上)、高力学性能(拉伸强度100MPa以上)和低介电常数(?=2.8-3.6)于一身,所以适合在电子电路中作为绝缘衬底和电子封装材料使用。然而,随着超大规模集成电路的迅速发展,电子元器件的尺寸越做越小,要求聚酰亚胺提供更好的介电性能来降低阻容延迟效应,降低能量损耗,即具有更低的介电常数。本论文通过冠醚(Crown ether,CE)与二胺单体的络合作用,将冠醚作为主体分子,PI主链作为客体分子,分别采用不同种类的冠醚、二胺和二酐作为反应物,制备了一系列PI/CE复合薄膜,通过核磁共振谱、红外光谱、X射线衍射、热失重分析、扫描电镜、介电频谱仪、拉力试验机等对其结构和性能进行了详细的研究。1.将15-冠醚-5(15-CE)和18-冠醚-6(18-CE)与4,4’-二氨基二苯醚(ODA)单体形成主客体包合物以后,再与均苯四酸酐(PMDA)缩聚,通过原位聚合合成了聚酰胺酸(PAA),即PMDA-ODA型PAA-1/15-CE和PAA-1/18-CE两种前驱体,经过旋涂成膜和热酰亚胺化后制备了不同冠醚含量的PI-1/15-CE和PI-1/18-CE的复合薄膜。核磁和红外结果证明了冠醚与ODA单体的络合作用,以及冠醚与PI-1主链的项圈式主客体包合结构,热失重结果说明了其包合率为50%;正电子湮没寿命测试说明了冠醚的添加增大了复合膜的分子自由体积,当冠醚添加量为ODA单体摩尔量的0.4倍时,复合膜的介电常数可以降低至2.99,杨氏模量、拉伸强度和断裂伸长率分别提升至4.86GPa、130MPa和51.8%,分别提高了73.0%、9.2%和135%。2.通过18-冠醚-6与ODA或者4,4’-二氨基-2,2’-双三氟甲基联苯(TFDB)之间的络合作用,再与PMDA或者4,4’-六氟亚异丙基邻苯二甲酸酐(6FDA)缩聚,分别制备了ODA-PMDA无氟型PI-1/18-CE、ODA-6FDA半氟型PI-2/18-CE、TFDB-6FDA全氟型PI-3/18-CE三种不同氟含量的复合薄膜,同样用核磁氢谱、红外光谱、热裂解质谱、热重红外联用和热失重分析证明了18-CE与几种不同PI主链之间的超分子结构和50%的包合率。引入F原子后,增大了分子自由体积,减小了分子极化率,增强了材料疏水性,使得薄膜介电常数更低,而力学性能有所下降。但随着18-CE添加量的增多,含氟复合膜的力学性能在原有基础上得到了补强,其中当18-CE添加量为二胺单体摩尔量的0.4倍时,全氟型PI-3/18-CE复合膜的介电常数会继续降低至2.72。3.通过烯丙氧基多缩三乙二醇和多缩三乙二醇双对甲苯磺酸酯的脱水关环反应制备了两种端基为烯丙氧基的ACE和端基为烯十一碳氧基的11-ACE改性冠醚,其环形醚键结构与18-CE一样。以它们为主体化合物,以简单的原位聚合反应,制备了不同冠醚含量下的PMDA-ODA型PI-1/ACE和PI-1/11-ACE两种主客体包合薄膜。研究表明,其主客体包合率为50%,引入的烯丙氧基侧链提高了18-CE的热稳定性,冠醚的加入不仅增大了分子自由体积,还会在热酰亚胺化过程中受热挥发引入空气孔洞,其中当含有长烷基侧链的11-ACE添加量为ODA摩尔量0.4倍时,复合膜介电常数可以降低至2.17。4.通过硅氢加成反应合成了三(三甲基硅氧基)封端的不同侧链长度的两种冠醚,其环形醚键结构与18-CE一样,并且作为主体分子,与PI-1客体分子一起制备了不同冠醚含量下的PI-1/SiCE和PI-1/11-SiCE两种主客体包合薄膜,研究结果说明,由于硅氧烷封端的冠醚分子极化率低、疏水性强,且含有树枝状的分子结构,可以增大分子自由体积,引入更多的空气孔洞,降低复合膜吸水率和介电常数。当11-SiCE添加量为ODA单体摩尔量的0.4倍时,复合膜杨氏模量较本体PI-1提升了55%以上,拉伸强度和断裂伸长率也可以和本体PI-1保持相当水平,在1MHz测试频率下的介电常数低至1.94,可以满足现代超大规模集成电路对介电材料的应用要求。更多还原

【Abstract】 Polyimide(PI) is a kind of high performance engineering plastics with wide applications range and in great demand, which has good thermal resistance(the onset temperature for thermal decomposition over 500oC),excellent mechanical properties(tensile strength over 100MPa) and low dielectric constant(?=2.8-3.6). It is very suitable to use in electric circuits as insulating substrates and electronic packaging materials. However, with the rapid development of ultra large scale integrated circuits, the size of electronic components is smaller and smaller, which requires polyimide to possess the better dielectric property to reduce the resistance capacitance delay effect and energy loss,that is to say,to get lower dielectric constant.This paper prepared a series of PI/crwon ether(CE) composite films by using different kinds of CE, diamine and dianhydride as reactants through complexation between CE and diamine monomer, in which the CE acted as host molecules and PI backbone acted as guest molecules.The structure and properties were studied by nuclear magnetic resonance spectroscopy, infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, dielectric spectroscopy,tensile testing machine and so on.1. After 15-crown-5(15-CE) or 18-crown-6(18-CE) formed host guest inclusion complexes with 4,4’-oxidianiline(ODA) monomer, pyromellitic dianhydride(PMDA) was added to polymerize into two kinds of precursors polyamic acid(PAA), PAA-1/15-CE and PAA-1/18-CE by in-situ polycondensation.PI-1/15-CE and PI-1/18-CE composite films with different contents of CE were preparedfollowing spin coating and thermal imidization.NMR and IR results demonstrated the complexation between crown ether and ODA monomer, and thenecklace-like host guest inclusion structure. Thermal gravimetric results illustrated the inclusion rate was 50%.Positron annihilation lifetime test showed that the crown ether increasedthe molecular free volume ofcomposite films. When the molar ratioof 18-crown-6to ODA amount was 0.4, the dielectric constant of the composite film could be reduced to 2.99, while Young’s modulus, tensile strength and elongation at break could be enhanced to 4.86 GPa, 130 MPa and 51.8%, respectively.2. Three kinds of composite films with different fluoride content were prepared through polycondensation of4,4’-(Hexafluoroisopropylidene)diphthalic anhydride(6FDA) or PMDA and complex between18-crown-6 and ODA or 2,2’-bis(trifluoromethyl)benzidine(TFDB), named as non-fluorinated PI-1/18-CE,semi-fluorinatedPI-2/18-CE and perfluorinated PI-3/18-CE.The supramolecular structure between 18-CE and several different PI backbones was analyzed in detail.The introduction of F atoms increased molecular free volume, reduced molecular polarizability,and enhanced hydrophobicity, which decreased the film dielectric constant, and the mechanical properties. But with the increasement of amount of 18-CE, the mechanical properties of fluorinatedcomposite films wereimproved, and the dielectric constant of PI-3/18-CE composite films continued to reduce to 2.72 whenthe molar ratioof 18-crown-6 to TFDB amount was 0.4.3. Two kinds of crown ether ACE and 11-ACE with different length of side chain were prepared through the dehydrating cyclization between allyloxy triethylene glycol and triethylene glycol ditosylate for ACE and between triethylene glycol ditosylate and α-undecylene oxymethyltriethylene glycol for 11-ACE.Then PI-1/ACE and PI-1/11-ACE supramolecularcomposite films were synthesized byin-situ polymerization, in whichACE or 11-ACE acted as host molecules and PI-1 backbone acted as guest molecules. The result showed that the host-guest inclusion rate was 50%, and the introduction of side chain containing allyloxy orα-undecylene oxymethylimproved the thermal stability of 18-CE.These modifiedcrown ethers not only increased the molecular free volume, but also introduced air holes in the thermal imidization process by volatilizing the decomposed crown ether. When the molar ratio oflong alkyl side chain 11-ACE to ODA was 0.4, the dielectric constant of PI-1/11-ACE composite films could be reduced to 2.17.4. Two kinds of crown etherwith different side chain length terminated by tri-(trimethylsilyloxy)were synthesized through the silicon hydrogen addition reaction and as host molecules to fabricate two kinds of host-guest composite films PI-1/SiCE and PI-1/11-SiCE with different content of crown ether.The results suggested that the siloxane group in crown ether molecules decreased the polarization rate and hydrophilicity. Furthermore,the siloxane group with dendrimers structure could increase the molecular free volume, introduce more air holes, and reduce the waterabsorption and dielectric constant of composite films.When the molar ratio of 11-SiCE to ODA dosage was 0.4,Young’s modulus of the composite filmenhancedmore than 50%,while the tensile strength and elongation at break maintained a considerable level, compared to PI-1. The dielectric constant of PI-1/11-SiCE composite films could be reduced to 1.94 and meet the requirement of the application in modern ultra large scale integrated circuit.更多还原