共聚制备低热膨胀透明聚酰亚胺薄膜

为了在尽量不影响其透光性的前提下解决含氟聚酰亚胺薄膜热膨胀系数(CTE)过大的问题,以4,4′-(六氟异丙烯)二酞酸酐(6FDA)、4,4′-二氨基-2,2′-双三氟甲基联苯(TFMB)和3,3′,4,4′-联苯四羧酸二酐(BPDA)为原料,通过两步法合成了5种BPDA掺杂量分别为0、10%、20%、30%和40%的共聚PI薄膜,并采用红外光谱分析(IR)、热重分析(TGA)、热机械性能分析(TMA)等方法对其性能进行了表征.分析表明:共聚薄膜的热性能相比均聚薄膜有所提高;薄膜的介电常数与BPDA的含量成正比,而其在可见光领域的透光率与BPDA的含量成反比;在BPDA含量较低时,薄膜的拉伸强度和弹性模量随BPDA含量的增加而增大,但当BPDA摩尔分数超过30%时其力学性能开始降低;随着共聚单体含量的上升,薄膜的热膨胀系数大幅减小.     

基于2-苯基-4,4′-二氨基二苯醚的异构聚酰亚胺

以异构的联苯二酐(BPDA)、二苯醚二酐(ODPA)以及2-苯基-4,4′-二氨基二苯醚(p-ODA)为原料,通过一步法或两步法,合成了一系列异构聚酰亚胺,并表征了这类聚酰亚胺的溶解性、热性能和力学性能。结果表明:基于p-ODA的聚酰亚胺在有机溶剂中具有优异的溶解性;基于p-ODA的异构聚酰亚胺都是非晶结构,且聚酰亚胺的溶解性和玻璃化温度(Tg)呈现3,3′-位3,4′-位4,4′-位的趋势,聚合物Tg250℃。聚合物4,4′-ODPA/p-ODA具有较优的热稳定性,5%热失重温度(T5%)=551℃,聚合物3,4′-ODPA/p-ODA和4,4′-ODPA/p-ODA具有相似的机械性能。异构BPDA/p-ODA系列聚酰亚胺具有相似的热稳定性,T5%550℃,聚合物4,4′-BPDA/p-ODA的机械性能优异,薄膜拉伸强度为182.4MPa、模量为3.5GPa、断裂伸长率为44.2%。     

热塑性共聚聚酰亚胺薄膜的合成及性能研究

以2,2′-二甲基-4,4′-二氨基联苯(m-TB)为二胺单体,均苯四甲酸二酐(PMDA)和3,3′,4,4′-联苯四甲酸二酐(BPDA)为二酐单体,N,N′-二甲基乙酰胺(DMAc)为溶剂,采用常规的两步法制备了一系列不同二酐比例的热塑性聚酰亚胺,并通过红外光谱仪、X-射线衍射仪、热重分析仪、紫外光谱仪、动态热分析仪、溶解性测试等对共聚聚酰亚胺的结构和性能进行表征.结果表明:在1 780、1 720、1 500、1 380、1 050和725 cm~(-1)处出现明显的吸收峰,说明成功制备了聚酰亚胺材料;共聚聚酰亚胺只在PMDA与BPDA物质的量比为0.2∶0.8时存在结晶峰,其他比例时均为非晶聚合物;亚胺化后的共聚聚酰亚胺在DMSO、DMAc、DMF、NMP和m-cresol中有溶解性,证明成功制备出热塑性聚酰亚胺薄膜;热塑性共聚PI起始分解温度大于500℃,800℃时的质量保持率在50%以上,具有良好的热稳定性;随着聚合物中BPDA含量的提高,热塑性聚酰亚胺薄膜的玻璃化转变温度呈现下降的趋势.当紫外光波长达到400 nm时,薄膜的透光率高达57.6%,当波长为760 nm时,薄膜透光率均达到100%,成功制备了透光率较高的聚酰亚胺薄膜.     

溶液缩聚法制备聚酰亚胺绝缘膜及性能研究

以联苯四酸二酐(BPDA)和4,4’-二氨基二苯醚(ODA)为单体原料,利用溶液缩聚法制备聚酰亚胺(PI)绝缘膜,采用XRD、SEM、FT-IR对不同热亚胺化温度合成的PI薄膜结构和表面形貌进行了表征,利用超高阻微电流测试仪测试了热亚胺化温度和粉体含量对PI绝缘膜击穿场强的影响。结果表明,在真空度为1.0×10-2Pa条件下,300℃热亚胺化1h,聚酰亚胺酸(PAA)薄膜完全被热亚胺化,制备的PI绝缘膜内部结构致密;当BPDA和ODA的粉体含量为5%时,PI绝缘膜击穿场强高达2.15MV/cm,表明PI薄膜具有良好的电学性能。     

黏度可控化制备BPDA-PDA型聚酰亚胺及表征

通过二酐水解程度控制改性聚酰亚胺前驱体的方法,对3,3′,4,4′-联苯四酸二酐(BPDA)-对苯二胺(PDA)型聚酰亚胺前驱体溶液的黏度进行调控。前驱体的化学结构通过红外光谱(FT-IR)和核磁氢谱(~1H-NMR)进行表征,并考察二酐水解对前驱体溶液黏度、亚胺化过程和材料性能的影响。结果表明:水解BPDA与PDA反应生成的前驱体,同时含有酰胺酸和羧酸铵盐官能团结构;羧酸铵盐的引入可降低前驱体溶液黏度,实现黏度在10～10~5cP范围内的有效调控;羧酸铵盐的存在未影响前驱体的完全亚胺化,使得材料力学性能得到保持;同时,该黏度调控方法具有降低BPDA-PDA型聚酰亚胺薄膜热膨胀系数的作用。     

砜基取代高折射率高透明性聚酰亚胺的合成与性能

首先合成了同时含有砜基与硫醚键的二胺单体,4,4′-双(4-胺基苯硫基)二苯砜(BADPS).采用BADPS分别与4种二酐单体,3,3′,4,4′-联苯四羧酸二酐(BPDA)、3,3′,4,4′-二苯醚四羧酸二酐(ODPA)、4,4′-双(3,4-二羧基苯硫基)二苯硫醚二酐(3SDEA)以及1,2,3,4-环丁烷四羧酸二酐(CBDA)通过两步聚合工艺制备了一系列聚酰亚胺(PI).制备的PI薄膜具有优良的综合性能,包括良好的热稳定性、可见光波长范围内优良的透明性以及高折射率与低双折射.10mm厚的PI薄膜在450nm处的透光率超过80%.全芳香族PI(PI-1～PI-3)的折射率＞1.70,双折射＜0.02.     

一类含双叔丁基苯结构聚酰亚胺的合成与性能

通过分子设计制备一种含双叔丁基结构的刚性芳香二胺单体——4,4′-二氨基苯基-3″,5″-二叔丁基甲苯,将该二胺单体分别与3种不同的商品化芳香二酐(3,3′,4,4′-联苯四酸二酐(BPDA)、3,3′,4,4′-二苯醚酐(ODPA)、3,3′,4,4′-二苯酮四酸二酐(BTDA))采用一步高温缩聚制备了3种新型聚酰亚胺NPI(3a～3c)。该类聚酰亚胺具有优异的溶解成膜性能,在室温可溶解于N-甲基-2-吡咯烷酮、N,N-二甲基乙酰胺、间甲酚等高沸点溶剂中,在加热时还能溶解于CHCl_3,CH_2Cl_2,THF等低沸点溶剂,并可通过其聚合物溶液浇铸得到柔韧的薄膜;所制聚酰亚胺薄膜具有优良的热性能,玻璃化转变温度(T_g)范围为262～303℃,在N_2中质量损失10%的温度超过523℃;具有优异的光学性能,所制薄膜还具有较浅的颜色和良好的光学透过性,在450 nm波长光下的透光率为69%～76%,截止波长为341～353 nm。     

2-苯基-4,4′-二氨基二苯醚及其聚酰亚胺的制备和性能表征

通过四步反应制备得到2-苯基-4,4′-二氨基二苯醚(PDADPE),其结构通过傅里叶红外光谱表征。该单体与3,3′,4,4′-联苯四羧酸二酐(BPDA)聚合得到聚酰亚胺薄膜(PI-2),4,4′-二氨基二苯醚(ODA)与BPDA聚合得到PI-1。对PI-1和PI-2进行傅里叶红外的结构表征。性能测试结果表明PI-2溶解性好于PI-1,分解5%的温度分别为514.0℃(PI-2)、512.5℃(PI-1),最大透过率为86.9%(PI-2)、86.2%(PI-1),表面能分别为44.3mJ/m2(PI-2)、37.6mJ/m2(PI-1),吸水率分别为0.92%(PI-2)、0.95%(PI-1),拉伸断裂强度分别为134.9MPa(PI-2)、112.0MPa(PI-1)。     

APTES交联型聚酰亚胺气凝胶的制备与表征

以低成本的3-氨丙基三己氧基硅烷(APTES)为交联剂,4,4′-二氨基二苯醚(ODA)为二胺单体,3,3′,4,4′-联苯四甲酸二酐(BPDA)或均苯四甲酸二酐(PMDA)为二酐单体,采用溶胶-凝胶和化学亚胺化方法,结合CO₂超临界干燥技术,制备出两种不同二酐单体的交联型聚酰亚胺气凝胶。采用FTIR、SEM、N₂吸脱附、万能材料试验机、热重分析等手段来表征样品的化学组成、微观形貌、孔结构、压缩性能及热稳定性,研究了二酐单体种类对聚酰亚胺气凝胶的压缩性能及热稳定性的影响。结果表明:采用BPDA和PMDA制备的交联型聚酰亚胺气凝胶都具有纳米尺度的纤维状网络结构,具有密度低(0.102 g/cm³和0.121 g/cm³)和比表面积大(295 m²/g和311 m²/g)的特性。以PMDA为单体的交联型聚酰亚胺气凝胶10%应变对应的压缩强度和压缩模量分别为0.37 MPa和5.3 MPa,高于以BPDA为单体的交联型聚酰亚胺气凝胶(0.17 MPa和3.0 MPa)。此外,前者制得的聚酰亚胺的初始热分解温度为543 ℃,高于后者制得的聚酰亚胺的初始热分解温度(502 ℃)。     

含咪唑基团的聚酰亚胺薄膜的制备及性能

为了探究适用于柔性印刷线路板的高热稳定性、低热膨胀系数聚酰亚胺薄膜,将3,3’,4,4’-联苯四甲酸二酐(3,3’,4,4’-BPDA)与4,4’-二氨基二苯醚(4,4’-ODA)和2-(4-氨基苯基)-5-氨基苯并咪唑(DAPBI)单体进行聚合,通过改变2种二胺的用量制备了一系列不同二胺比例的聚酰亚胺薄膜。采用红外、紫外、热重分析、差示扫描量热、动态力学热分析、热机械分析多种测试方法对不同比例薄膜样品的热性能、热稳定性、动态力学性能和光透过性进行了研究。研究结果表明,随着刚性DAPBI组分的增加,所制备薄膜的玻璃化转变温度逐渐升高,耐热性能变好,储能模量从3.5 GPa逐渐增加到5.9 GPa;薄膜的热膨胀系数(CTE)明显减小。当二胺ODA与DAPBI的摩尔比为4:6或5:5时,共聚薄膜的CTE值最接近18×10^-6K^-1。     

共聚低热膨胀聚酰亚胺薄膜的制备与表征

以4,4′-(六氟异丙烯)二酞酸酐(6FDA)为含氟二酐,4,4′-二氨基-2,2′-双三氟甲基联苯(TFMB)为含氟二胺,通过引入分子结构相对对称的刚性单体1,2,4,5-均苯四甲酸二酐(PMDA)进行共聚合成了5种含氟比例不同的透明聚酰亚胺薄膜,并对其性能进行了表征。分析表明:引入刚性单体共聚后薄膜的热稳定性和耐热性有所提高;薄膜的介电常数随着PMDA含量的上升而增加;共聚薄膜在可见光领域的透光率低于均聚薄膜;拉伸实验显示在添加少量PMDA后,薄膜的拉伸强度和弹性模量有所增大,但当PMDA含量过高时其力学性能反而下降;随着PMDA含量的增加,薄膜的热膨胀系数明显降低。     

表面改性纳米TiO2粒子杂化PI薄膜的制备与性能研究

采用硅烷偶联剂(γ-巯丙基三乙氧基硅烷)对纳米TiO2粒子进行表面处理,通过原位聚合和流延成膜法制备了不同TiO2含量的PI/TiO2杂化膜,研究了杂化膜的热性能、力学性能,并通过扫描电镜(SEM)和广角X衍射(WAXD)研究了杂化膜的微观形貌结构,同时也对杂化膜的接触角和介电常数(ε)进行了研究分析.结果表明,杂化膜较纯膜的热分解温度(T5％)降低,但平均热分解温度仍然高于520℃,且膜的尺寸稳定性得到了提高,即热膨胀系数( CTE)降低;表面形貌分析表明,1％～5％的表面改性纳米TiO2能较好地分散在PI膜里,杂化膜的介电常数(3.50左右)均高于纯膜的的介电常数(2.91),杂化膜的接触角随着TiO2含量的增加呈现先减少后增加的趋势.     

共聚物链结构对共聚型含氟聚酰亚胺薄膜性能的影响

以4,4'-二氨基-2,2'-双三氟甲基联苯(TFMB)、4,4'-(六氟异丙烯)二酞酸酐(6FDA)和3,3',4,4'-联苯四甲酸二酐(BPDA)为反应单体,改变非含氟BPDA单体在二酐中的配比和加料方式制备出一系列共聚型含氟聚酰亚胺(PI)薄膜并表征和分析其性能,研究了共聚物链结构对其性能的影响。结果表明,BPDA单体的加料方式及其在二酐单体中的比例均影响薄膜的性能。共聚型含氟PI薄膜在室温下均溶于非质子极性溶剂,且在可见光范围内有较高的透光率。随着非含氟二酐单体BPDA含量的提高薄膜的光学性能略有降低而其热性能和力学拉伸性能提高。非含氟二酐单体占二酐单体的比例为68.97%的共聚型PI薄膜,在500 nm处的透过率达到96.01%;非含氟二酐单体占二酐单体比例为35.71%的共聚型PI薄膜失重10%的热分解温度为595.23℃,拉伸强度为100.98 MPa。同时,BPDA加料方式的改变对共聚型PI薄膜的光学性能、热学性能和力学拉伸性能均有不同程度的影响。     

High temperature polyimide containing anthracene moiety and its structure, interface, and nonvolatile memory behavior

A high temperature polyimide bearing anthracene moieties, poly(3,3'-di(9-anthracenemethoxy)-4,4'-biphenylene hexafluoroisopropylidenediphthalimide) (6F-HAB-AM PI) was synthesized. The polymer exhibits excellent thermal stability up to around 410 °C. This polymer is amorphous but orients preferentially in the plane of nanoscale thin films. In device fabrications of its nanoscale thin films with metal top and bottom electrodes, no diffusion of the metal atoms or ions between the polymer and electrodes was found; however, the aluminum bottom electrode had somewhat undergone oxide layer (about 1.2 nm thick) formation at the surface during the post polymer layer formation process, which was confirmed to have no significant influence on the device performance. The polymer thin film exhibited excellent unipolar and bipolar switching behaviors over a very small voltage range, less than ±2 V. Further, the PI films show repeatable writing, reading, and erasing ability with long reliability and high ON/OFF current ratio (up to 10(7)) in air ambient conditions as well as even at temperatures up to 200 °C.     

气相沉积聚合法制备聚酰亚胺绝缘薄膜及其性能研究

以联苯四酸二酐和4,4’-二氨基二苯醚为单体原料使用气相沉积聚合(VDP)法制备了聚酰亚胺(PI)绝缘膜,分析不同热亚胺化处理温度对PI薄膜绝缘性能的影响。分别使用红外光谱、俄歇能谱、扫描电镜、原子力显微镜对薄膜成分以及薄膜表面形貌进行了表征;利用超高阻微电流测试仪测试了PI复合绝缘膜漏电流和电压击穿特性。结果表明:热亚胺化300℃/1 h真空(1.0×10-2Pa)处理后的PI绝缘膜内部结构致密,当场强为8.0MV/cm时漏电流密仅为8.2×10-5A/cm2;薄膜击穿场强达到8.42MV/cm,表明PI薄膜具有良好的电学性能以及热稳定性。     

Separation of CO2 and CH4 through two types of polyimide membrane

Two asymmetric polyimide membranes that have a thermal stability up to 550 K and good resistance to solvents were prepared. Some membrane-forming conditions such as coagulation solution, evaporation and immersion time were examined. Regarding the coagulation solution, a water–methanol mixture gives good membranes in eleven solutions tested. The permeabilities of two asymmetric polyimide membranes for CO₂ and CH₄ pure gases were determined at 25°C and at applied pressures up to 0.25 MPa. The prepared polyimide membranes, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA)-4,4′-diaminodiphenyl ether (ODA) and 1,2,3,4-butanetetracarboxylic dianhydride (BDA)-4,4′-diaminodiphenyl ether (ODA) exhibited higher selectivity and permeability for CO₂/CH₄.     

Synthesis and characterization of polyimide-based hybrid thin films from a novel colloidal core-shell nanocomposite particles

In this study, poly(4,4-(hexafluoroisopropylidenediphthalic anhydride)-co-oxydianiline) (6FDA-ODA) and a novel core-shell nanoparticle consisting of a core (SnO2/TiO2) and a shell (ZrO2/Sb2O3) with the composition (SnO2:TiO2:ZrO2:Sb2O3 = 18:5:3:4) were used to prepare polyimide/nanoparticles hybrid thin films. The resultant hybrid thin films were investigated by FTIR, TGA, DSC, TEM, SEM, AFM, alpha-step, UV-Vis, and n&k analyses. The results show that the prepared hybrid thin films had a good thermal stability. The size of nanoparticles was effectively controlled in the range of 8-10 nm in the hybrid thin films. These nanoparticles were evenly distributed across the hybrid thin films and no phase separation occurred. In terms of the optical properties, the prepared hybrid thin films had good transparency in the range of visible light. The cutoff wavelength had a blue shift as the content of the nanoparticles increased. The refractive index of prepared hybrid thin films increased with corresponding increases in nanoparticle content. Moreover, the prepared polyimide/core-shell nanoparticle hybrid thin films displayed excellent film formability and planarity.     

Polyimide/sepiolite nanocomposite films: Preparation, morphology and properties

Polyimide/sepiolite nanocomposite films have been prepared via an in situ polymerization method. The process involves the dispersion of sepioite in N,N-dimethylacetamide, polycondensation of 2,2′-bis [4-(3,4-dicarboxyphenoxy) phenyl] propane dianhydride and 4,4′-oxydianiline in the presence of sepiolite suspension to form poly(amic acid), and the thermal imidization of poly(amic acid)/sepiolite nanocomposite. The morphology, thermal and mechanical performance, and water absorption of nanocomposite films were systematically studied with various sepiolite contents. The results indicated that sepiolite was dispersed homogeneously at a nanometer scale in polyimide matrix. Owing to such nanodispersion of sepiolite, the polyimide/sepiolite nanocomposite films exhibit dramatic improvements on the mechanical properties and the coefficient of thermal expansion while fine thermal stability and low water absorption capacity were also maintained. When the sepiolite content increased to 16% the polyimide/sepiolite nanocomposite film achieved as much as 41% and 94% increase on the tensile strength and modulus respectively, and 50% decreased in coefficient of thermal expansion.     

Preparation SnO₂ nanolayer on flexible polyimide substrates via direct ion-exchange and in situ oxidation process

Tin oxide (SnO(2)) nanolayers were formed on flexible polyimide (PI) substrate via direct ion-exchange and in situ oxidation process utilizing pyromellitic dianhydride/4,4'-oxidianiline-based poly(amic acid) films as polyimide precursor. During an ion-exchange process, stannous ions were doped into the precursor by immersion in ethanolic solution of stannous chloride. Subsequent thermal treatment of the tin(II)-containing precursor at a constant heating rate not only imidized poly(amic acid) to PI but also converted stannous ions into SnO(2) clusters, which diffused and aggregated onto the surface of polymer matrix, forming continuous tin oxide layers. Inductively coupled plasma (ICP) was used to investigate the ion-exchange process. Changes in chemical structure of the poly(amic acid) film and the crystal structure of tin oxides were analyzed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) and X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to study the microstructure of the PI/SnO(2) nanocomposite films. The nanocomposite film maintained essential mechanical property and thermal stability of pristine PI films.     

Characterization of 6FDA-APBP polyimide films through impulsive stimulated thermal scattering

The elastic and thermal properties of 4,4-(hexafluoroisopropylidene)-bis (phthalic anhydride)-4,4-bis (4-aminophenoxy) biphenyl (6FDA-APBP) free-standing polyimide films (2–10 m) were investigated using impulsive stimulated thermal scattering (ISTS), a non-contact optical method for thin film characterization. Shear and longitudinal velocities, Young's modulus, Poisson's ratio and the in-plane thermal diffusivity are reported.