新型光敏聚酰亚胺/SiO2杂化材料的制备与性能研究

通过溶胶－凝胶法制备了一种新型的光敏聚酰亚胺／二氧化硅杂化材料。研究表明当ＳｉＯ２的含量≤１０ｗｔ％时杂化材料除了保持光敏聚酰亚胺原有的感光性能外其热稳定性能、力学性能以及与基底的粘附性能均有明显地提高,同时材料的热膨胀系数也显著地降低。     

Role of SiNx Barrier Layer on the Performances of Polyimide Ga2O3-doped ZnO p-i-n Hydrogenated Amorphous Silicon Thin Film Solar Cells

In this study, silicon nitride (SiN_x) thin films were deposited on polyimide (PI) substrates as barrier layers by a plasma enhanced chemical vapor deposition (PECVD) system. The gallium-doped zinc oxide (GZO) thin films were deposited on PI and SiN_x/PI substrates at room temperature (RT), 100 and 200 °C by radio frequency (RF) magnetron sputtering. The thicknesses of the GZO and SiN_x thin films were controlled at around 160 ± 12 nm and 150 ± 10 nm, respectively. The optimal deposition parameters for the SiN_x thin films were a working pressure of 800 × 10⁻³ Torr, a deposition power of 20 W, a deposition temperature of 200 °C, and gas flowing rates of SiH₄ = 20 sccm and NH₃ = 210 sccm, respectively. For the GZO/PI and GZO-SiN_x/PI structures we had found that the GZO thin films deposited at 100 and 200 °C had higher crystallinity, higher electron mobility, larger carrier concentration, smaller resistivity, and higher optical transmittance ratio. For that, the GZO thin films deposited at 100 and 200 °C on PI and SiN_x/PI substrates with thickness of ~000 nm were used to fabricate p-i-n hydrogenated amorphous silicon (α-Si) thin film solar cells. 0.5% HCl solution was used to etch the surfaces of the GZO/PI and GZO-SiN_x/PI substrates. Finally, PECVD system was used to deposit α-Si thin film onto the etched surfaces of the GZO/PI and GZO-SiN_x/PI substrates to fabricate α-Si thin film solar cells, and the solar cells’ properties were also investigated. We had found that substrates to get the optimally solar cells’ efficiency were 200 °C-deposited GZO-SiN_x/PI.     

基于三蝶烯架构的固有微孔聚酰亚胺网络的制备及其吸附特性

通过三氨基三蝶烯与3,4,9,10-苝四羧酸酐（PTCDA）、均苯四甲酸酐（PMDA）、3,3’,4,4’-联苯二酐（BPDA）以及螺环二酐（SBIDA）的缩聚反应分别合成了4种固有微孔聚酰亚胺材料(Trip-PIMs)。采用傅里叶红外光谱（FT-IR）、固体核磁碳谱（Solid-state 13C-NMR）、扫描电子显微镜（SEM）、热重分析(TG)和氮气吸附等测试手段表征了材料的微孔结构和物理化学性能,测试了材料对有机气体和液体的吸附性能。结果表明：三蝶烯结构的引入使材料获得了较高的比表面积,同时具有良好的溶胀特性;对比烷烃,该材料对胺类和苯类具有更高的吸附率;螺环结构的引入能进一步提高材料骨架的溶胀特性,从而提升材料的吸附能力。     

Graphitized-rGO/Polyimide Aerogel as the Compressible Thermal Interface Material with Both High in-Plane and through-Plane Thermal Conductivities

Reduced graphene oxide (rGO) aerogels with a three-dimensional (3D) interconnected network provides continuous heat transport paths in multi-directions. However, the high porosity of rGO aerogels commonly leads to very low thermal conductivity (TC), and defects and grain boundaries of rGO sheets result in a high extent of phonon scattering, which is far from satisfying the requirement of thermal interface materials (TIMs). Here, a compressible graphitized-rGO/polyimide (g-rGO/PI) aerogel was prepared by the ice-template method and “molecular welding” strategy. The regular cellular structure and closely packed cell walls bring the g-rGO/PI aerogel high compressibility, which made the aerogel can maintain the continuous thermal transport paths well even in highly compacted status. The rGO sheets in the cell wall surface are welded up by g-PI during imidization and graphitization treatment, providing efficient channels for phonon transportation in the 3D network. The g-rGO/PI aerogel in a compressive strain of 95% has a high TC in the plane of 172.5 W m⁻¹k⁻¹ and a high TC through the plane of 58.1 W m⁻¹k⁻¹, which is superior to other carbon-based TIMs previously reported.     

Interlaminar Fracture Behavior of Carbon Fiber/Polyimide Composites Toughened by Interleaving Thermoplastic Polyimide Fiber Veils

Carbon fiber reinforced thermosetting polyimide (CF/TSPI) composites were interleaved with thermally stable thermoplastic polyimide (TPPI) fiber veils in order to improve the interlaminar fracture toughness without sacrificing the heat resistance. Both of the mode I and mode II interlaminar fracture toughness (G_IC and G_IIC) for the untoughened laminate and TPPI fiber veils interleaved laminates were characterized by the double cantilever beam (DCB) test and end notch flexure (ENF) test, respectively. It is found that the TPPI fiber veils interleaved laminates exhibit extremely increased fracture toughness than the untoughened one. Moreover, the areal density of TPPI greatly affected the fracture toughness of laminates. A maximum improvement up to 179% and 132% on G_IC and G_IIC is obtained for 15 gsm fiber veils interleaved laminate, which contributes to the existence of bicontinuous TPPI/TSPI structure in the interlayer according to the fractography analysis. The interlaminar fracture behavior at elevated temperatures for 15 gsm fiber veils interleaved laminate were also investigated. The results indicated that the introduction of thermally stable TPPI fiber veils could enhance the fracture toughness of CF/TSPI composites by exceeding 200% as compared to the untoughened one even as tested at 250 °C.     

Direct Pattern Growth of Carbon Nanomaterials by Laser Scribing on Spin-Coated Cu-PI Composite Films and Their Gas Sensor Application

The excellent physical and chemical properties of carbon nanomaterials render them suitable for application in gas sensors. However, the synthesis of carbon nanomaterials using high-temperature furnaces is time consuming and expensive. In this study, we synthesize a carbon nanomaterial using local laser-scribing on a substrate coated with a Cu-embedded polyimide (PI) thin film to reduce the processing time and cost. Spin coating using a Cu-embedded PI solution is performed to deposit a Cu-embedded PI thin film (Cu@PI) on a quartz substrate, followed by the application of a pulsed laser for carbonization. In contrast to a pristine PI solution-based PI thin film, the laser absorption of the Cu-embedded PI thin film based on Cu@PI improved. The laser-scribed carbon nanomaterial synthesized using Cu@PI exhibits a three-dimensional structure that facilitates gas molecule absorption, and when it is exposed to NO₂ and NH₃, its electrical resistance changes by −0.79% and +0.33%, respectively.     

Layer-by-Layer Electrode Fabrication for Improved Performance of Porous Polyimide-Based Supercapacitors

Nanoporous polymers are becoming increasingly interesting materials for electrochemical applications, as their large surface areas with redox-active sites allow efficient adsorption and diffusion of ions. However, their limited electrical conductivity remains a major obstacle in practical applications. The conventional approach that alleviates this problem is the hybridisation of the polymer with carbon-based additives, but this directly prevents the utilisation of the maximum capacity of the polymers. Here, we report a layer-by-layer fabrication technique where we separated the active (porous polymer, top) layer and the conductive (carbon, bottom) layer and used these “layered” electrodes in a supercapacitor (SC). Through this approach, direct contact with the electrolyte and polymer material is greatly enhanced. With extensive electrochemical characterisation techniques, we show that the layered electrodes allowed a significant contribution of fast faradic surface reactions to the overall capacitance. The electrochemical performance of the layered-electrode SC outperformed other reported porous polymer-based devices with a specific gravimetric capacitance of 388 F·g⁻¹ and an outstanding energy density of 65 Wh·kg⁻¹ at a current density of 0.4 A·g⁻¹. The device also showed outstanding cyclability with 90% of capacitance retention after 5000 cycles at 1.6 A·g⁻¹, comparable to the reported porous polymer-based SCs. Thus, the introduction of a layered electrode structure would pave the way for more effective utilisation of porous organic polymers in future energy storage/harvesting and sensing devices by exploiting their nanoporous architecture and limiting the negative effects of the carbon/binder matrix.     

Development of a novel polyimide hollow-fiber oxygenator

We have developed a membrane oxygenator using a novel asymmetric polyimide hollow fiber. The hollow fibers are prepared using a dry/wet phase-inversion process. The gas transfer rates of O(2) and CO(2) through the hollow fibers are investigated in gas-gas and gas-liquid systems. The polyimide hollow fiber has an asymmetric structure characterized by the presence of macrovoids, and the outer diameter of the hollow fiber is 330 microm. It is found that the polyimide hollow-fiber oxygenator can enhance the gas transfer rates of O(2) and CO(2), and that the hollow fiber provides excellent blood compatibility in vitro and in vivo.     

6FDA型聚酰亚胺的合成及其分子量调控

以4,4′-(六氟异丙烯)二酞酸酐(6FDA)为二酐单体,2,2双(3-胺基-4-羟基苯)六氟丙烷为二胺单体,采用“溶液缩聚亚胺化反应”两步合成法,获得了可溶性聚酰亚胺材料。通过傅里叶变换红外光谱 (FT-IR)、凝胶色谱(GPC)、热重分析(TGA)、X射线衍射(XRD)等分析测试,考察了原料配比、亚胺化温度、亚胺化时间及催化剂等因素对产物重均分子量等特性参量的影响。结果表明：通过调节合成条件,该聚酰亚胺重均分子量可达4.5×104,具有优良的热稳定性,其起始分解温度高于490 °C,且在NMP、DMF、DMAc、DMSO、THF、丙酮等有机溶剂中具有优良的溶解性能,能于80 °C的低温下亚胺化制得,对材料的大批量制备具有重要意义。     

联苯型聚酰亚胺纤维的动态力学行为

采用干湿法纺丝工艺路线制备联苯型聚酰亚胺(PI)纤维，用动态力学分析方法研究了该纤雏的γ、β和α转变，因所施频率的不同而发生的相应转变温度分别出现在-100--40℃、100℃和270-300℃。用类似的Arrhenius方程计算了PI纤维γ转变活化能为38．7kJ／mol，α转变的活化能为853kJ／mol。