八氨基倍半硅氧烷改性聚酰胺酰亚胺基润滑涂层的性能研究

为开发苛刻服役环境下高性能、长寿命的有机润滑涂层,以氨基丙基三乙氧基硅烷（KH550）为原料制备了八氨基倍半硅氧烷（ NH₂-POSS）,并将其添加到聚酰胺酰亚胺基涂层（ HM-1100A）中,研究了改性前后涂层的结构、力学性能和摩擦性能。结果表明：经 NH2-POSS改性后的 HM-1100A涂层相比原始涂层具有更高的硬度、内聚强度及较低的表面能,并且涂层的摩擦性能有显著提高。通过对比 HM-1100A、KH550改性 HM-1100A及 NH₂-POSS改性 HM-1100A 3种涂层的热重、硬度、表面能和摩擦性能,研究了其作用机理,分析发现 NH₂-POSS独特的中空笼形结构和八官能团的引入有效提高了涂层的物理机械性能和摩擦性能。     

Enhancing aerogel mechanical properties with incorporation of POSS

Silica aerogels consisting of nanoparticles and numerous nano-pores have many attractive attributes. However, the weak mechanical properties severely limited the practical application of the silica aerogel. In this work, a facile approach was employed to strengthen the silica aerogel while the multi-alkoxy polyhedral oligomeric silsesquioxane (POSS) joined with methyltriethoxysilane (MTES) as the co-precursor. Three kinds of stiff core POSS with different amount of alkoxy groups were chosen to prepare aerogels. The result attributes showed all aerogels owned mesoporous structure (10–20 nm), high specific surface area (760–877 m² g⁻¹) and good thermal stability. Moreover, with the introduction of POSS, the mechanical properties had been apparently enhanced. The suitable addition of functional groups and the adjustment of cross-linking density made the aerogel own more room to deform and the skeleton still strong enough to endure large deformation. In addition, new peaks appeared in the XRD patterns at the same time. The preparation strategy of composite aerogels may guide a facile way to regulate the aerogel attributes. Furthermore, the aerogel potential application in oil-water separation has also been investigated.     

笼型倍半硅氧烷(POSS)/环氧杂化树脂体系固化反应动力学及性能研究

为了提高环氧树脂的耐热性,采用笼型倍半硅氧烷(POSS)改性双酚A型环氧树脂E51,得到有机无机杂化树脂。采用Ozawa和Kissinger两种方法研究了杂化树脂/4,4′-二氨基苯砜(DDS)体系的固化反应动力学。TGA分析表明,POSS的加入提高了E51/DDS固化树脂体系的热性能。     

Preparation and the catalytic activity of novel Pd nanocluster catalysts utilizing an oligosilsesquioxane ligand

Palladium acetate together with a newly synthesized silsesquioxane- pyridyl ligand showed excellent catalytic activity towards the aerobic oxidation of benzyl alcohol to benzaldehyde. TEM measurements revealed the in situ formation of Pd nanoclusters during the reaction period.     

Effect of additive structure and size on SiO2 formation in polymer‐derived SiOC ceramics

Silicon oxycarbide (SiOC) ceramics with highly adjustable properties and microstructures have many promising applications in batteries, catalysis, gas separation, and supercapacitors. In this study, additive structures on the nucleation and growth of SiO₂ within SiOC ceramics are investigated by adding cyclic tetramethyl‐tetravinylcyclotetrasiloxane (TMTVS) or caged octavinyl‐polyhedral oligomeric silsesquioxane (POSS) to a base polysiloxane (PSO) precursor. The effects of the 2 additives on the polymer‐to‐ceramic transformation and the phase formation within the SiOC are discussed. POSS encourages SiO₂ nucleation and leads to more SiO₂ formation with significantly increased ceramic yield, which subsequently leads to higher specific surface of 1557 m²/g with a larger pore size of ～1.8 nm for the porous SiOC. High TMTVS content decreases both the specific surface area and pore volume of the resulting porous SiOCs. This study demonstrates a new approach of using Si‐rich additive POSS to increase the SiOC yield while maintaining or even increasing the specific surface area.     

POSS改性有机玻璃研究进展

目的 多面体低聚倍半硅氧烷(POSS)/聚合物复合材料是近年来材料科学领域研究的热点.把具有特殊笼型结构的新型有机-无机纳米粒子POSS用于改性有机玻璃(PMMA),可以提高PMMA的热学、力学和阻燃等性能,从而提升PMMA的使用效能,拓宽其应用领域.方法 通过对文献进行分析,阐明POSS的合成方法、特性和应用,并全面综述POSS改性PMMA的应用研究进展.结论 分析了目前POSS改性PMMA相关研究的不足,并提出了POSS改性PMMA拓展代替钢化玻璃应用于高层建筑和传统透明材料应用包装领域拟解决的关键问题.     

Cationic Phenosafranin Photosensitizers Based on Polyhedral Oligomeric Silsesquioxanes for Inactivation of Gram-Positive and Gram-Negative Bacteria

The high photodynamic effect of the Newman strain of the S. aureus and of clinical strains of S. aureus MRSA 12673 and E. coli 12519 are observed for new cationic light-activated phenosafranin polyhedral oligomeric silsesquioxane (POSS) conjugates in vitro. Killing of bacteria was achieved at low concentrations of silsesquioxanes (0.38 µM) after light irradiation (λ_{em. max} = 522 nm, 10.6 mW/cm²) for 5 min. Water-soluble POSS-photosensitizers are synthesized by chemically coupling a phenosafranin dye (PSF) (3,7-diamino-5-phenylphenazine chloride) to an inorganic silsesquioxane cage activated by attachment of succinic anhydride rings. The chemical structure of conjugates is confirmed by ¹H, ¹³C NMR, HRMS, IR, fluorescence spectroscopy and UV-VIS analyzes. The APDI and daunorubicin (DAU) synergy is investigated for POSSPSFDAU conjugates. Confocal microscopy experiments indicate a site of intracellular accumulation of the POSSPSF, whereas iBuPOSSPSF and POSSPSFDAU accumulate in the cell wall or cell membrane. Results from the TEM study show ruptured S. aureus cells with leaking cytosolic mass and distorted cells of E. coli. Bacterial cells are eradicated by ROS produced upon irradiation of the covalent conjugates that can kill the bacteria by destruction of cellular membranes, intracellular proteins and DNA through the oxidative damage of bacteria.     

Studies on graft copolymerization of cyclohexyl methacrylate onto chloroprene rubber

Graft copolymerization of cyclohexyl methacrylate (CMA) onto chloroprene rubber (CR) was carried out in toluene using benzoyl peroxide as an initiator. The graft copolymer was isolated from the gross polymer by extracting it with a butanone solution. Infrared (IR) spectra of the graft copolymer showed the occurrence of grafting. Optimization of various parameters of the grafting, namely, time, temperature, and initiator concentrations, was performed. The mechanical adhesive properties of the graft copolymer, CR-g-CMA, were measured and compared with those of the graft copolymer of methyl methacrylate (MMA) onto CR, CR-g-MMA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1733–1737, 1997     

多面体低聚倍半硅氧烷晶粒诱导的聚乳酸结晶行为及性能

通过溶液及熔融两步共混方法,用带有环氧基的多面体低聚倍半硅氧烷(EVOS)对聚乳酸(PLA)进行改性,并对复合材料的力学性能、结晶性能和相态等方面进行了表征。实验结果表明,随着EVOS的加入,PLA冷结晶温度降低,结晶和熔融温度变化不大,结晶热和熔融热下降。1%的EVOS在PLA中实现了纳米尺度的分散,随着EVOS含量增加,球晶尺寸明显增加。当EVOS的添加量为5%时,材料的拉伸强度比纯PLA增加26.2%,达到最大值。     

不同硝基苯基POSS的合成及热性能研究

以八苯基笼型低聚倍半硅氧烷(OPS)和十二苯基笼型低聚倍半硅氧烷(DPS)为原料,经发烟硝酸和发烟硝酸/浓硫酸的混合酸硝化反应,分别合成了八硝基苯基笼型低聚倍半硅氧烷(ONPS),十二硝基苯基笼型低聚倍半硅氧烷(DNPS),十六硝基八苯基笼型低聚倍半硅氧烷(HDNPS)。利用傅里叶红外光谱、核磁共振光谱、XRD分析测试手段对其结构进行了表征。重点考察了笼子体积和硝基取代数对化合物热稳定性的影响,经TGA测试表明:三者质量损失为5%时的温度分别为349℃、292℃、187℃,最大热分解速度对应的温度分别是430℃、428℃、410℃,在1 190℃处,三者的残留质量分数分别是53.4%、50.25%、36.69%。三者都具有良好的热稳定性,其中以硝基取代数最少和笼子体积最小的ONPS热稳定最佳。