【作者】 李志强；

【导师】 林保平； 何维满；

【作者基本信息】 东南大学 ， 化学工程（专业学位）， 2021， 硕士

【摘要】 聚酰亚胺（PI）综合性能较为突出,具有优异的耐高温、耐低温、力学性能、耐溶剂性、阻燃性和较好介电性能,因此被广泛应用于制备电子器件。然而,传统芳香族PI由于二胺和二酐单体分子间易形成电子转移络合物（CTC）作用,从而导致PI薄膜颜色较深,透光率较低,与此同时,分子内刚性结构易导致其不熔不溶。随着光电行业的发展,对PI的耐热性、透光率和机械性能又有了更高的要求。传统PI已不能满足加工和使用需求。与PI相比,聚酰胺-酰亚胺（PAI）兼具PI和聚酰胺的优良性能,即具有良好的热稳定性、突出的机械性能、较低的热膨胀系数、优异的耐辐射性和耐腐蚀性,成为柔性电子器件的首选基底。但PAI的耐热性和透光率之间具有一定的冲突,很难同时满足加工要求,这限制了其在柔性电子设备方面的应用。基于此,本文合成了一系列具有高透光率、高耐热性和优秀力学性能的PAI薄膜,并对其各项性能做了详细表征与分析,主要工作内容包括以下三个方面:（1）PAI同时含有酰胺键和酰亚胺基团,与PI相比,分子内含有酰胺键,可在分子内形成氢键,使得其具有较好的机械性能和较高的玻璃化转变温度,综合性能较为突出。首先合成了含双酰胺键的二胺单体N,N’-双（4-氨基苯基）对苯二甲酰胺（APTA）。再以APTA为二胺单体,六氟二酐（6FDA）、3,3’,4,4’-联苯四羧酸二酐（BPDA）和4,4’-氧双邻苯二甲酸酐（ODPA）为二酐单体,经过两步法合成三种APTA系列PAI薄膜。作为对比,又以含单酰胺键的4,4二氨基苯酰替苯胺（DABA）为二胺单体,6FDA、BPDA和ODPA为二酐单体,制备了三种DABA系列的PAI薄膜。结果表明,二酐单体为6FDA的PAI表现出较好的透光性。APTA系列PAI的玻璃化转变温度明显高于DABA系列的PAI薄膜。在所有PAI薄膜中,APTA-6FDA薄膜具有优秀的综合性能,其玻璃化转变温度高达354.1℃,550 nm处透光率为81.41%,拉伸强度为142.51 MPa。（2）三氟甲基和脂环结构都可以破坏PAI分子链的共轭结构,降低分子密度,能够有效抑制分子间或分子内电子转移络合物（CTC）的形成,增大自由体积,从而提高PAI的透光性和溶解性。首先设计并合成了具有脂环结构和酰胺基团的二胺单体N,N’-（环己烷-1,4-二基）双（4-氨基苯甲酰胺）（NCHABA）。将NCHABA与含三氟甲基的2,2’-二（三氟甲基）二氨基联苯（TFDB）以不同比例混合,作为二胺单体,以6FDA为二酐单体,合成了四种不同TFDB含量的NCHABA系列共聚型PAI薄膜。作为对比,又将APTA与TFDB按不同比例混合作为二胺单体,以6FDA为二酐单体,合成了四种不同TFDB含量的APTA系列共聚型PAI薄膜。所有共聚型PAI薄膜都具有优秀的溶解性,常温下可溶于常见的有机溶剂。随着TFDB含量的增加,薄膜的透光率、5%热分解温度不断增加。NCHABA系列PAI薄膜的透光率高于APTA系列PAI薄膜,透光率最高分别达88.29%和87.21%。APTA系列PAI薄膜的热分解温度高于NCHABA系列PAI薄膜,5%热分解温度最高分别为516.3℃和473.0℃。（3）无机/有机聚合物复合材料可以将不同材料的优良性能集中起来,使得复合材料具有较好的综合性能。Si O₂热膨胀系数较低,耐热性较好,在PAI中掺入纳米级Si O₂可以同时提高PAI的耐热性及尺寸稳定性。将APTA、NCHABA分别与TFDB按照摩尔比1:4混合作为二胺单体,6FDA为二酐单体,KH550为偶联剂,正硅酸四乙酯为主要硅源,使用溶胶-凝胶法分别合成了APTA和NCHABA两种系列的PAI/Si O₂复合薄膜。结果表明,随着Si O₂含量的增加,复合薄膜的耐热性提高,5%热分解温度和玻璃化转变温度均增加。APTA和NCHABA系列复合薄膜5%热分解温度最高分别为525.5℃和497.3℃,玻璃化转变温度最高分别为336.7℃和315.6℃。更多还原

【Abstract】 Polyimide（PI）is widely used in electronic devices due to its high temperature resistance,low temperature resistance,solvent resistance,flame retardancy,good mechanical properties,and excellent dielectric properties.However,the easy formation of CTC between diamine and dianhydride monomer molecules often results in a darker color and lower light transmittance of PI film.At the same time,the rigid structure of the molecule causes it to be difficult to process.With the development of the optoelectronic industry,there are higher requirements for polyimide,especially its heat resistance,light transmission and mechanical properties.Compared with polyimide,polyamide-imide（PAI）has both the excellent properties of polyamide and polyimide such as lower thermal expansion coefficient,excellent radiation resistance and corrosion resistance,as well as high light transmittance.Therefore,it becomes a preferred substrate for flexible electronic devices.However,there is a certain conflict between the heat resistance and light transmittance of PAI,which is difficult to meet the machining requirements.Therefore,its application in flexible electronic equipment is very limited.Based on this,a series of PAI films with high light transmittance,high heat resistance,and excellent mechanical properties are synthesized in this paper,and their performance has been detailed and analyzed.The main work content includes the following three aspects:（1）In the PAI molecule,an amide bond and an imide group are simultaneously containing.Compared to the PI,the molecule contains an amide bond,which can form a hydrogen bond inside the molecule,improve its mechanical properties and glass transition temperatures and overall performance.By the molecular structure design,the diamine monomer N,N’-bis（4-aminophenyl）phthalamide（APTA）was synthesized.Using APTA as diamine monomer,4,4’-（Hexafluoroisopropylidene）diphthalic anhydride（6FDA）,3,3’,4,4’-biphenyl tetracarboxylic dianhydride（BPDA）and 4,4’-oxygen bisphenylenedic anhydride（ODPA）as dianhydride monomer,three APTA series PAI films were synthesized.As a contrast,three kinds of PAI films of DABA series were prepared by using 4,4’-diamino-benzoylaniline（DABA）as diamine monomer and 6FDA,BPDA and ODPA as dianhydride monomer.The results showed that PAI films with 6FDA dianhydride monomer have better light transmittance,and the glass transition temperature of APTA series PAI films was significantly higher than that of DABA series PAI films.Among all PAI films,APTA-6FDA film has excellent comprehensive properties,the glass transition temperature reaches 354.1°C,the light transmittance of 550 nm is 81.41%,and the tensile strength is 142.51 MPa.（2）Both trifluoromethyl and alicyclic structures can damage the conjugate structure of the PAI molecular chain,reduce molecular density and thereby effectively inhibit the formation of CTC in molecular or molecular.It also can increase the free volume of PAI,and improve its light transmittance and solubility.A novel diamine monomer N,N’-（cyclohexane-1,4-diyl）bis（4-aminobenzanamide）（NCHABA）with an adipocyclic structure and an amide group was synthesized.Four NCHABA series copolymerized PAI films with different TFDB contents were prepared by mixing NCHABA with 2,2’-bis（trifluoromethyl）diaminobiphenyl（TFDB）in different proportions as diamine monomer and using 6FDA as dianhydride monomer.As a contrast,four kinds of APTA series copolymerized PAI films with different TFDB contents were prepared by mixing APTA and TFDB in different proportions as diamine monomer and using 6FDA as dianhydride monomer.All copolymerized PAI films have excellent solubility,and can dissolve in common organic solvents at room temperature.As the TFDB content increases,the light transmittance and thermal decomposition temperature of the film is increasing.The light transmittance of NCHABA series PAI films is higher than that of APTA series PAI films,and the highest light transmittance is 88.29%and 87.21%,respectively.The thermal decomposition temperature of the APTA series PAI film is higher than the NCHABA series PAI film,and the highest 5%thermal decomposition temperature is 516.3°C and 473.0°C,respectively.（3）Inorganic/organic polymer composites can concentrate the excellent properties of different materials,therefore,composite materials have good comprehensive performance.Si O₂ has low thermal expansion coefficient and good heat resistance.Adding nano-sized Si O₂ into PAI can improve the heat resistance and dimensional stability of PAI at the same time.Two series of PAI/Si O₂ composite films,APTA and NCHABA,were synthesized by sol-gel method by mixing APTA and NCHABA with TFDB at molar ratio of 1:4 as diamine monomer,6FDA as dianhydride monomer,KH550 as coupling agent and tetraethyl osilicate as main silicon source.The results show that as the Si O₂ content increases,the heat resistance of the composite film is significantly improved,and the thermal decomposition temperature and the glass transition temperature are increased.The highest 5%weight loss temperature of the APTA and NCHABA series composite films is 525.5°C and497.3°C,respectively,and the glass transition temperature was 336.7°C and 315.6°C.更多还原