【作者】 孙芳；

【导师】 田国峰；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2024， 硕士

【摘要】 透明聚酰亚胺（CPI）是一种具有重要应用前景的先进功能材料,不仅兼顾了传统聚酰亚胺（PI）突出的耐温性能和力学性能,同时表现出良好的光学性能,解决了传统PI材料呈黄色或棕色的问题,广泛应用于柔性光电显示、太阳能电池、柔性印刷电路板、微电子设备等领域。理想的柔性有机发光二极管（OLED）基板材料既需承受加工时的高温（400°C）,又要避免因各层间材料热膨胀系数（CTE）不匹配导致的组件开裂,还要达到器件底部发光技术要求的高透过率。为了给柔性OLED用CPI薄膜提供满足上述性能要求的结构选择,本论文对PI的分子结构进行设计,采用不同的亚胺化方法,制备了一系列高透过率、高玻璃化转变温度（T_g）、低CTE和高弹性模量（E）的CPI薄膜。首先将含氟二酐4,4’-（六氟异亚丙基）二邻苯二甲酸酐（6FDA）和柔性脂环二酐3,3’,4,4’-氢化联苯四甲酸二酐（4,4’-HBPDA）分别与对苯二胺（p-PDA）、4,4’-二氨基二苯醚（4,4’-ODA）、1,4-双（4-氨基苯氧基）联苯（p-BAPB）、2,2’-双（三氟甲基）-4,4’-二氨基苯基醚（6FODA）聚合,经过热亚胺化的方法制备CPI薄膜,并对均聚体系进行性能测试。结果表明,以6FDA为二酐的体系中,6FDA/6FODA体系具备高透过率,在450 nm处透过率为86.86%。三氟甲基（—CF₃）的吸电子性阻碍PI分子内电荷转移,抑制分子链内CTC形成,改善薄膜的光学性能,PI薄膜的光学透过率随—CF₃在结构中占比的增加而提高。该体系T_g为296°C,CTE为65.22 ppm/°C,E为2.36 GPa。以4,4’-HBPDA为二酐的体系均具备高透过率。柔性脂环不含共轭结构,抑制分子链内CTC的生成。其中,A-CPI-1体系具备良好的综合性能,在波长450 nm处透过率为87.38%,T_g为311°C,CTE为60.29 ppm/°C,E为2.19 GPa。为了进一步改善CPI薄膜的综合性能,在A-CPI-1体系的分子结构基础上,依此引入含有酰胺结构的N,N’-（2,2’-双（三氟甲基）-[1,1’-二联苯基]-4,4’-二基）双（4-氨基苯甲酰胺）（AB-TFMB）和含刚性脂环的环丁烷四甲酸二酐（CBDA）制备共聚CPI薄膜。酰胺键有利于形成分子间氢键,增强链间相互作用,限制链段运动;刚性脂环结构扭转程度低,刚性强,链段不易运动,提高分子链的有序度使分子链堆砌紧密。结果表明,CPI-B-4体系能够兼顾高透过率(T_{450 nm}=83.01%)、高T_g（401°C）和低CTE（13.38 ppm/°C）。此外,为了研究亚胺化方法对CPI薄膜性能的影响,本论文将化学法和热法相结合,对CPI-B-4体系进行改性。化学法和热法相结合的工艺增强了分子链的有序度,易形成区域性的高取向状态,使链段排列更加规整。经过对比分析,C-CPI-50%体系综合性能最佳:在450 nm处透过率为86.86%,T_g为409°C,CTE为12.16 ppm/°C,E为6.20 GPa,基本满足柔性OLED基板材料的加工条件和应用需求。光伏（PV）太阳能电池的输出功率与接收太阳光照情况紧密相关,因此冰雪覆盖极大影响PV太阳能电池的发电效率。针对这个问题,本论文设计了一种以高透过PI为基体,以磷烯（PR）纳米片为光热转换因子的被动自除冰复合薄膜,以实现太阳能驱动光热除冰的目标。PR作为一种具有直接带隙的半导体,能够通过吸收大于其带隙的入射光子能量,将太阳光转化为热能。采用原位聚合,以含氟单体6FDA和6FODA为原料制备高透过率PI基体,并与一定质量分数的PR复合,经阶段升温热亚胺化制备了FPI/PR复合薄膜。所得复合薄膜能满足PV太阳能电池板对太阳光的直接利用,同时具有优异的光热转换能力和良好的光热自除冰效果。本论文为实现快速光热自除冰,促进PV光伏电池板的输出电压快速恢复到冰雪覆盖前的理想值提供了一种新的方法,以保证太阳能光伏板在冰雪天气下的发电量和发电效率。更多还原

【Abstract】 Transparent polyimide（CPI）is an advanced functional material with important application prospects,which takes into account the outstanding temperature resistance and mechanical properties of traditional polyimide（PI）,shows good optical properties at the same time,solving the problem of yellow or brown color of traditional PI materials,and is widely used in the fields of flexible photovoltaic displays,solar cells,flexible printed circuit boards,microelectronic devices and so on.Ideal flexible organic light-emitting diode（OLED）substrate materials need to withstand high temperatures（400°C）during processing,and avoid component cracking due to the mismatch of coefficients of thermal expansion（CTE）of the materials between the layers to achieve the device requirements,such as a high transmittance of light-emitting technology at the bottom.In order to provide CPI films structural options for flexible OLEDs to meet the above performance requirements,the molecular structure of PI was designed in this project,and a series of CPI films with high transmittance,high glass transition temperature（T_g）,low CTE,and high elastic modulus（E）were prepared by using different imidization methods.The fluorinated dianhydride 4,4’-（hexafluoroisopropylidene）diphthalic anhydride（6FDA）and the alicyclic dianhydride 3,3’,4,4’-hydrogenated biphenyl tetracarboxylic acid dianhydride（4,4’-HBPDA）were firstly mixed with p-phenylenediamine（p-PDA）,4,4’-diaminodiphenyl ether（4,4’-ODA）,1,4-bis（4-aminophenoxy）biphenyl（p-BAPB）,2,2’-bis（trifluoromethyl）-4,4’-diaminophenyl ether（6FODA）,respectively.CPI films were prepared by thermal imidization and the homopolymerization system was tested for its properties.The results showed that among the systems with 6FDA as dianhydride,the 6FDA/6FODA system possessed high transmittance with 86.86%at 450 nm.The electron-absorbing property of trifluoromethyl（—CF₃）inhibite the charge transfer within the PI molecule,the formation of CTCs is inhibited in molecular chains,and improves the optical properties of the film.The optical transmittance of the PI film increases with the increase of the proportion of—CF₃ in the structure.T_g is296°C,CTE is 65.22 ppm/°C and E is 2.36 GPa.The flexible lipid ring excluding conjugate structure and inhibits the generation of CTC within the molecular chain.The systems with 4,4’-HBPDA as dianhydride all possessed high transmittance,and the A-CPI-1 systems possessed good overall performance with 87.38%at 450 nm,T_g is 311°C,CTE is 60.29 ppm/°C and E is 2.19 GPa.In order to further improve the comprehensive performance of CPI films,based on the molecular structure of the A-CPI-1 system,N,N’-（2,2’-bis（trifluoromethyl）-[1,1’-dibiphenyl]-4,4’-diyl）bis（4-aminobenzamide）（AB-TFMB）and cyclobutane tetracarboxylic acid dianhydride（CBDA）containing a rigid aliphatic ring were used to prepare copolymerized CPI films.The amide bond facilitates the formation of intermolecular hydrogen bonds,enhances interchain interactions,and restricts the movement of chain segments;the rigid alicyclic structure has a low degree of torsion,strong rigidity,and the chain segments are not easy to move,which improves the degree of order of the molecular chain so that the molecular chain is tightly stacked.The results showed that the CPI-B-4 system was able to combine high transmittance(T_{450 nm}=83.01%),high T_g（401°C）and low CTE（13.38 ppm/°C）.In addition,in order to study the effect of imidization methods on the performance of CPI films,this project combines chemical and thermal iminization methods to modify the CPI-B-4 system.The combined chemical and thermal process enhances the orderliness of the molecular chains and tends to form a regional highly oriented state,resulting in a more regular chain segment arrangement.After comparative analysis,the C-CPI-50%system has the best overall performance:transmittance is 86.86%at 450 nm,T_g is 409°C,CTE is12.16 ppm/°C,E is 6.20 GPa,basically meets the processing conditions and application requirements of flexible OLED substrate materials.The output power of a photovoltaic（PV）solar cell is closely related to the amount of sunlight it receives,so snow and ice cover greatly affect the efficiency of PV solar cells.To address this problem,a passive self-deicing composite film with high transmittance PI as the matrix and phosphorene nanoflakes（PR）as the photothermal conversion factor was designed in this work to achieve the goal of solar-driven photothermal deicing.PR as a semiconductor with a direct bandgap,is able to convert sunlight into heat by absorbing the energy of incident photons larger than its bandgap.Using in situ polymerization,high transmittance PI matrix was prepared from fluorine-containing monomers 6FDA and 6FODA,and compounded with a certain mass fraction of PR,and FPI/PR composite films were prepared by stage-raising thermal imidization.The resulting composite film can satisfy the direct utilization of sunlight by PV solar panels,and at the same time has excellent photothermal conversion capability and good photothermal self-deicing effect.This topic provides a new method for realizing rapid photothermal self-deicing and promoting the output voltage of PV solar panels to quickly return to the ideal value before ice and snow cover,so as to ensure the power generation and power generation efficiency of solar PV panels under ice and snow.更多还原