硅倍半氧烷改性聚酰亚胺(PI/Si)复合膜性能

通过在聚酰亚胺(PI)中分别添加笼型八氨基苯基硅倍半氧烷(OAPS)、 笼型八苯基硅倍半氧烷(OPS)、 梯形聚苯基硅倍半氧烷(PPSQ)和无机纳米SiO₂, 制备了4种含硅聚酰亚胺(PI/Si)复合膜. 对PI/Si复合膜的相容性、 力学性能、 热性能和阻燃性能进行了研究. 结果表明, OAPS与PI间展现出较好的相容性, PPSQ次之, 而OPS, SiO₂与PI的相容性较差; 但相容性与复合膜的力学和热性能无明显的对应关系. SiO₂可提高PI的力学性能; PI/OAPS复合膜的T_g最高; OAPS, PPSQ或SiO₂的加入使PI复合膜的热稳定性稍有提高, 而少量OPS的加入大大降低PI膜的热稳定性. 这类PI/Si复合膜的显著特点是能够大幅提高PI膜的极限氧指数, 含硅化合物能够增加PI燃烧后残炭量, 使残炭的形貌得到显著改善. PI/Si复合膜在燃烧过程中在表面形成一层白色含硅包裹层, 起到隔热隔氧及保护内层有机物不被燃烧的作用. 硅倍半氧烷对炭层形貌的改善显著, 展现出比SiO₂更好的阻燃性能.     

多面体低聚八(二苯砜基)硅倍半氧烷合成优化及磺酰化机理研究

以笼型低聚八苯基硅倍半氧烷(OPS)为原料,AlCl3为催化剂,苯磺酰氯为磺酰化试剂,在二氯甲烷溶液中反应72h,合成了笼型八(二苯砜基)硅倍半氧烷(ODPSS).该方法合成过程简单稳定,产率高.通过FTIR、MALDI-TOF MS、1H NMR、13C NMR、29Si NMR和元素分析对产物进行了表征,证明OPS已完全转化为ODPSS.通过改变溶剂、催化剂、反应时间和各反应物物质的量之比,优化了反应条件,分析了反应机理,建立了该体系下OPS的磺酰化反应机理模型.     

多面体低聚八氨基苯基硅倍半氧烷合成方法改进及其表征

以八硝基苯基硅倍半氧烷(ONPS)为原料, 5% Pd/C 和FeCl₃ 为催化剂, 水合肼为还原剂, 在四氢呋喃溶液中反应 1 h 合成了八氨基苯基硅倍半氧烷(OAPS). 相比文献中已有的其它合成方法, 该方法合成过程简单且稳定, 催化效率高、产率高、周期短. 通过FTIR, ¹H NMR, GPC 对产物进行了表征, 证明了硝基已完全转化. 通过催化剂的控制, 分离出ONPS 向OAPS 转化过程中的一种含有羟胺和二羟胺基团的中间体. 分析了OAPS 合成机理, 提出了ONPS 和水合肼的反应历程. 认为ONPS 中的硝基先经过2 电子转移转化为二羟胺化合物, 然后经过脱水加氢生成羟胺化合物, 最后再经过脱水加氢生成OAPS; 在有ONPS 存在的情况下, 水合肼主要转化为氮气和氢气, 待ONPS 完全转化为OAPS 后, 水合肼转化为氮气和氨气.     

八苯基笼型倍半硅氧烷的官能化及其在高分子纳米复合材料中的应用

笼型倍半硅氧烷（POSS）是具有独特分子结构的有机硅化合物,无机硅氧骨架核心为其提供良好的硬度和热稳定性,外围有机基团可增强与聚合物基体间的相容性,以它为前驱体可以制备分子级分散的有机／无机纳米高分子杂化材料。近年来,全芳香结构的八苯基笼型倍半硅氧烷因其高的耐热性和官能化方法的多样性尤其得到关注。本文重点综述了八苯基笼...     

多面体低聚八硝基苯基硅倍半氧烷纯度分析

使用高效液相色谱-电喷雾四级杆飞行时间质谱(HPLC-ESI-Q-TOF MS)联用技术对八硝基苯基硅倍半氧烷(ONPS)纯度进行分析, 从而判定ONPS产物峰及杂质峰的位置, 根据ONPS峰和杂质峰的面积比计算ONPS的纯度. 通过改变HPLC的洗脱梯度和测试时间, 将ONPS产物中的杂质峰完全分开, 测得硝基苯基硅倍半氧烷(NPS)质量分数为97.55%, 其中ONPS的纯度约为92.42%, 产物中含有九硝基八苯基硅倍半氧烷(9-NPS)约5.13%, 其它杂质含量约为2.45%. 通过对ONPS高效液相色谱图峰形和同分异构体极性情况分析, 进一步证明ONPS分子中硝基取代发生于对位和间位. 使用超高效液相色谱(UPLC)对ONPS进行分析, 以更高的分离效率验证了HPLC的结果. 该方法可作为ONPS纯度的分析方法.     

聚有机硅倍半氧烷的合成及其在涂层材料中的应用

聚有机硅倍半氧烷由于具有优异的力学、电学、光学性能,近年来被广泛应用作涂层材料以提高其热稳定性、耐腐蚀性、耐磨性、耐刮伤性、绝缘性等。介绍了聚有机硅倍半氧烷的合成方法及其在涂层材料中的应用。     

抗原子氧聚酰亚胺的研究与应用进展

聚酰亚胺(PI)在空间飞行器中广泛用作多层热绝缘毯、太阳电池阵列的柔性基板以及电路系统的绝缘保护层。但普通型PI在低地球轨道(LEO)原子氧环境中易发生降解。因此,提高PI材料抗原子氧能力的研究近年来受到了广泛的重视。本文概述了这一研究领域内的最新进展情况,重点阐述了含苯基氧化膦(PPO)、含笼型低聚倍半硅氧烷(POSS)以及含锆基PI材料的结构与抗原子氧特性之间的关系。最后结合作者的研究工作对国内抗原子氧PI材料的研究与应用前景进行了展望。     

大分子植酸-聚有机硅倍半氧烷的合成及性能

采用溶胶-凝胶方法, 无需小分子酸催化剂, 利用硅烷化植酸的反应活性和酸催化活性, 与硅烷单体共水解缩聚, 在聚有机硅倍半氧烷分子链上原位接枝植酸, 合成了分子量大于50000的大分子植酸-聚有机硅倍半氧烷. 用GPC, 13C NMR, 29Si NMR, XPS, Raman光谱, SEM及电化学测试等分析手段进行表征, 对比不同酸催化植酸-聚有机硅倍半氧烷(PAP), 单宁酸-聚有机硅半氧烷(TAP), 盐酸-聚有机硅半氧烷(HCP)的结构和性能, 发现植酸-聚有机硅倍半氧烷上的螯合基团与金属表面的活性基团反应而键合, 在金属表面形成致密的保护膜, PAP与TAP和HCP比较具有优异的防腐性能.     

色谱用金属柱管的脱活研究

利用苯基三乙氧基硅烷的酸催化水解缩合反应合成了具有梯形结构的聚苯基硅倍半氧烷预聚体，再以其20％－30％的丙酮溶液对气相色谱用金属柱管进行遮盖性脱活，预聚体涂层经溶剂挥发高温老化处理后获得了能耐400℃高温的脱活涂层，。以甲醇、乙醇、异丙醇、叔丁醇为测试物，内径2mm、长3．0m，固定相为PorapackQ的填充聚四氟乙烯柱为预分离柱串接测试柱的方法对该涂层进行了评价，结果表明，经该涂层处理的不锈钢柱管在115℃时对低级醇的吸附活性与PorapackQ柱的活性相近，活性明显降低，涂层结构中含有的苯环和羟基等官能基，将提高其与固定液的相容性并为固定液的交联提供必要的活性点。     

星形聚硅氧烷的热稳定性研究和结构表征

含六苯基环三硅氮烷 (P3N)的聚硅氧烷的低温性能与普通聚硅氧烷相当 .35 0℃ ,封闭氮气中老化2 4h后 ,含P3N 聚硅氧烷的热失重比普通聚硅氧烷低 4～ 10倍 ,随聚合物含氮量增加 ,其失重呈下降趋势 ,最低失重为 1 1% .六苯基环三硅氮烷三锂盐 (P3NLi)引发环硅氧烷聚合得到的含P3N 聚硅氧烷的2 9Si NMR谱、IR谱和分子量 (GPC)与特性粘数的关系证明其具有星形结构     

Phenolic resin/polyhedral oligomeric silsesquioxane (POSS) composites: Mechanical,ablative, thermal,and flame retardant properties

Three different polyhedral oligomeric silsesquioxanes (POSS), trisilanolphenyl polyhedral oligomeric silsesquioxane (T‐POSS), octaaminophenyl polyhedral oligomeric silsesquioxanes (OAPS), and octaphenyl polyhedral oligomeric silsesquioxanes (OPS) were incorporated into phenolic resin (PR), respectively; PR/POSS composites were successfully prepared, and the properties of PR/POSS composites were studied. The limiting oxygen index (LOI), cone calorimeter, and thermal gravimetric analysis (TGA) were used for the estimation of flame retardancy and thermal stability. Oxyacetylene flame test and flexural strength test were used to study the ablative and mechanical properties of the PR/POSS composites. The results indicated that T‐POSS was more effective in improving the flame retardancy of PR than OAPS or OPS. Meanwhile, compared with pure PR, the second line ablation rates of PR/4% T‐POSS, PR/4% OAPS, and PR/4% OPS were significantly reduced by 53.3%, 61.9%, and 40.0%, respectively. In addition, the thermal stability and flexural strength of PR/4% T‐POSS were significantly higher than that of all other PR composites.     

Crystallization and flame‐retardant properties of polylactic acid composites with polyhedral octaphenyl silsesquioxane

To develop environmental‐friendly and flame‐retarded polymer composites, bio‐based polylactic acid (PLA) was loaded with thermally stable polyhedral octaphenyl silsesquioxane (OPS). Pure PLA and PLA/OPS composites with the OPS of 1, 3, 5, and 10 wt% were prepared by extrusion and injection molding, respectively. The scanning electron microscopy (SEM), polarized optical microscope (POM), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), and thermal gravimetric analysis (TGA) were used to analyze the dispersion of the OPS in the PLA matrix and the effects of OPS on the crystallization and thermal stability properties of PLA/OPS composites, respectively. Limited oxygen index (LOI) and cone calorimeter (CONE) measurements were used to study flame retardancy of PLA and PLA/OPS composites. In order to study the flame‐retardant mechanism, the char residues were investigated by SEM, Fourier transform infrared spectra (FTIR), and X‐ray photoelectron spectroscopy (XPS). TGA‐FTIR was used to analyze the gaseous products of their thermal decomposition. The results show that the OPS particles were submicron in the PLA and could increase the crystallization rate of PLA and form small‐sized secondary α‐form crystalline compared with the pure PLA spherulite. The PLA and OPS decomposed individually in the PLA/OPS composites by TGA. According to the LOI tests, the PLA with the OPS loading exhibited very small reduction of LOI. However, the CONE tests indicated that the OPS could improve the flame retardancy of the PLA by means of low peak heat release rate and average heat release rate. It was obtained that the degree and type of the PLA crystalline for the pure PLA and PLA/OPS affect their flame retardancy. In the max thermal decomposition stage of PLA and PLA/OPS, their gaseous products were similar; at high temperatures, the PLA/OPS produced simple and clear gaseous products of PLA with solid SiO₂ in the gas phase.     

The influence of silicone shell on double-layered microcapsules in intumescent flame-retardant natural rubber composites

The mechanisms of the thermal degradation of polyhedral oligomeric octaphenylsilsesquioxane (OPS), octa(nitrophenyl)silsesquioxane (ONPS), and octa(aminophenyl)silsesquioxane (OAPS) were investigated. The –NO₂ or –NH₂ substituents on the phenyl group affected the mechanism of the POSS thermal degradation. The thermal stabilities of OPS, ONPS, and OAPS were characterized by TG and FTIR. Thermal degradation of OPS included mainly the degradation of caged polyhedral oligomeric silsesquioxane structures and phenyl groups. Nitro or amino substituents decreased its thermal stability. The thermal degradation processes of OPS, ONPS, and OAPS differed. Phenyl groups and cyclobutadiene were observed in the OPS degradation products. Oxygen radicals that caused intensive CO₂ release between 350 and 450 °C were generated by the degradation of ONPS –NO₂. OAPS released mainly aminophenyl groups at 370 °C, whereas a small number of phenyl groups decomposed at 500 °C. The OAPS reactivity could enhance the thermal stability of POSS structure in the polyimide OAPS composites.     

Preparation of poly(phenylsilsesquioxane) (PPSQ) particles with ladder structure and the thermal stability of PP/PPSQ composites

The poly(phenylsilsesquioxane) (PPSQ) particles were prepared with both basic and acidic catalyzed processes and the PP/PPSQ composites were prepared by melt blending method. Studies on PPSQ by Infrared (IR), X‐ray diffraction (XRD), ²⁹Si cross polarized (CP) nuclear magnetic resonance (NMR) spectroscopy showed that the structure of PPSQ was ladder structure. The results of scanning electron microscopy (SEM) confirmed that the prepared PPSQ particles were about 2 µm with narrow size distributions. The morphology and thermal stability of PP/PPSQ composites were characterized by SEM, XRD, and thermogravimetric analysis (TGA). The SEM result showed that the particles were well dispersed in the PP matrix and the XRD revealed that the addition of PPSQ influences the crystallinity and crystal orientation of PP. The thermogravimetric analysis results of the PP/PPSQ composites indicated that the incorporation of PPSQ can improve the thermal stability of PP. The Flynn–Wall–Ozawa method was employed to analyze the TGA data and the kinetic results showed that the apparent activation energy for PP/PPSQ composites was much higher than that of neat PP, suggesting that the PPSQ influences the mechanisms of pyrolysis of PP. Copyright © 2010 John Wiley & Sons, Ltd.     

Mechanical and flame‐retardant properties and thermal decomposition of vinyl ester resin modified by different phenyl silsesquioxanes

The mechanical properties and fire resistance of vinyl ester resin (VER) composites containing cage‐shaped octaphenyl silsesquioxane (OPS), incompletely cage‐shaped phenyl silsesquioxane (PhT₇POSS), and ladder‐shaped phenyl silsesquioxane (PPSQ) were investigated. The POSS structure and dispersion have a great influence on the mechanical properties, thermal stability, and decomposition process of VER composites. The bending strength at break and modulus of the VER‐POSS composites were enhanced obviously, especially for VER‐PPSQ composite and VER‐OPS composite, respectively. In addition, PhT₇POSS‐based VER composites revealed the lower values of the peak heat release rate, total heat release, and total smoke release in cone calorimetry tests due to the formation of dense carbon/silica protective layers that acted as a barrier to heat and mass transfer. Moreover, the flame‐retardant mechanisms of condensed phase and gas phase were also investigated in detail. These results illustrate VERs modified by OPS, PhT₇POSS, and PPSQ are providing an applicable method to fabricate the composites with excellent flame‐retardant and mechanical properties.     

含磷聚酰亚胺纤维的制备与性能

合成了一种含磷二胺单体, 二(4-胺基苯氧基)苯基膦氧(DAPOPO). 该单体与4,4'-二胺基二苯醚(ODA)、 均苯四酸二酐(PMDA)和3,3',4,4'-联苯四酸二酐(BPDA)共聚得到聚酰胺酸溶液, 通过干喷湿纺法纺丝得到聚酰胺酸纤维, 聚酰胺酸纤维经过热亚胺化和热牵伸得到含磷的聚酰亚胺纤维. 利用纤维强度仪、 扫描电子显微镜、 热失重分析仪和氧指数测定仪等研究了含磷聚酰亚胺纤维的力学性能、 形貌、 热稳定性能和阻燃性能. 结果表明, 随着含磷量的增加, 纤维的热稳定性明显提高, 而极限氧指数从35上升到了45, 说明纤维的阻燃性能得到很大提高.     

磺化聚醚砜/磷酸硼复合质子交换膜的制备与性能

采用sol-gel法成功制备了一系列有望用于高温质子交换膜燃料电池的新型磺化聚醚砜(SPES)/磷酸硼(BPO4)复合膜, 并经热重分析(TGA)-傅立叶变换红外光谱(FTIR)联用技术、差示扫描量热仪(DSC)、扫描电子显微镜(SEM)等对膜的结构和性能进行了表征. 结果表明, 复合膜较纯SPES膜具有更高的热稳定性和玻璃化转变温度, 较低的溶胀性及较高的氧化稳定性; SEM图片显示BPO4在聚合物基体中的分布十分均匀, 这将有利于连续质子传输通道的形成; 复合膜的质子传导率随BPO4含量的增加而增加, 当温度超过120 ℃后, 复合膜仍保持着较高的质子传导率, 这表明该复合膜在高温质子交换膜燃料电池中具有良好的应用前景.     

Mixed matrix membranes of polysulfone/polyimide reinforced with modified zeolite based filler: Preparation,properties and application

In this work,polysulfone/polyimide (PSf/PI) mixed matrix membranes were fabricated by reinforcement of modified zeolite (MZ) particles through solution casting method for investigation of antibacterial activity against two gram negative bacteria (Salmonella typhi,Klebsellapneumonia) and two gram positive bacteria (Staphylococcus aureus,Bacillus subtilis).The modified zeolite particles were incorporated to PSf and PI matrix and the influence of these particles on thermal,mechanical and structural properties was evaluated.The morphological evolution was investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis,which revealed good compatibility between organic polymer matrix and inorganic filler.Mechanical stability was investigated by tensile testing while thermal analysis was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).This revealed improvement in thermal properties with increasing filler concentration from 1 wt％ to 10 wt％.Structural analysis was successfully done using X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy.Solvent content of fabricated mixed matrix membranes was observed to decrease while moving from more hydrophilic to less hydrophilic solvent.However,addition of filler content enhanced the porosity of fabricated membranes.The synthesized mixed matrix membranes exhibited good antibacterial activity and the highest activity was shown by PSf/PI/MZ mixed matrix membrane.Therefore,the combination effect of PSf,PI and MZ sufficiently enhanced the antibacterial activity of mixed matrix membranes.     

Preparation and characterization of inorganic–organic hybrid proton exchange membranes based on phosphorylated PVA and PEG-grafted silica particles

We reported proton-conducting membranes with novel microstructure based on partially phosphorylated poly(vinyl alcohol) (P-PVA) and polyethylene glycol (PEG) grafted silica (PEG-SiO₂) particles. The PEG-SiO₂ particles were synthesized through acid catalyzed hydrolysis and condensation reactions. The membranes were characterized for their mechanical, structural, morphological, and electrical properties by employing tensile test, Fourier transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), impedance analyzer, respectively. In these membranes, P-PVA acts as the proton source and PEG act as the proton solvent. The PEG-riched phases in the hybrid membrane form continuous ionic conducting pathways and subsequently give high ionic conductivity. The results suggest that the obtained membrane shows good thermal stability, excellent mechanical property and high ionic conductivity, and the low-cost hybrid membrane can be a promising candidate for intermediate temperature fuel cell systems.