Liquid polyoctahedral silsesquioxanes as an effective and facile reinforcement for liquid silicone rubber

Acrylo polyoctahedral silsesquioxanes (POSS), a liquid POSS derivative with reactive C=C double bond, is used to modify addition-cured liquid silicone rubber (LSR) as an effective nanofiller for the first time. Significant enhancements on mechanical properties are obtained. With addition of only 1.5 parts per hundred rubbers (phr) of acrylo POSS to fumed silica-strengthened silicones, the Young's modulus and ultimate tensile strength are increased by 432% and 66%, respectively, and the hardness of resulting LSR composites is improved as well. Proton nuclear magnetic resonance and Fourier transform infrared spectroscopies prove the efficient hydrosilylation between Acrylo POSS and hydrosiloxane directly. The thermal stability and morphology investigations also confirm that POSS is covalently incorporated into the network of silicone rubber. The increment of crosslink density is proved by extraction and swelling experiment and dynamic mechanical analysis. It can be envisioned that this simple and effective method could help produce high performance silicone rubber composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46996.     

Crystal structure and molecular packing of an asymmetric giant amphiphile constructed by one C60 and two POSSs

Based on our recent understanding and development of functionalized molecular nanoparticles (MNPs) as building blocks for constructing various giant molecules, we report our efforts on design and synthesis of an asymmetric giant amphiphile, diBPOSS–C₆₀, composed of one [60]fullerene (C₆₀) covalently linked with two isobutyl-functionalized polyhedral oligomeric silsesquioxane (BPOSS) MNPs. Its crystal structure and molecular packing were investigated. The compositional asymmetry between C₆₀ and BPOSS led to a “sandwich-layered” molecular packing scheme, where a single layer of C₆₀ is sandwiched between double BPOSS layers: a so-called “one-and-half-layered” structure. Within these layers, the molecules further organized into crystalline arrays. Interestingly, this compound can be viewed as size amplification of a class of atomically thin, two-dimensional layered transition metal dichalcogenides with the “one-and-half-layered” structure.     

Controlled accommodation of metal nanostructures within the matrices of polymer architectures through solution-based synthetic strategies

Controlled accommodation of metal nanostructures (MNSs) into the matrix of a well-defined polymer architecture offers an effective approach to achieve hierarchically structured nanocomposites with tunable synergistic properties to broaden application potentials in the emerging fields of energy, environmental science, and medicine. This review focuses on the recently developed zero-dimensional and one-dimensional MNSs@polymer hybrid nanostructures obtained by solution-based synthetic strategies. Progress in the controlled synthesis of those hybrid nanostructures in terms of the number (e.g., monomer, dimer and trimer), organization manner (e.g., linear alignment or confined assembly in certain domains), and spatial arrangement (e.g., in the core and shell) of the MNSs within the distinct polymer matrices are detailed. The synergistic properties and potential applications of those MNSs@polymer hybrids associated with their compositions and morphologies are also reviewed.     

[BMIm]Br离子液体辅助HZSM-5催化乙酸环己酯高选择性水解反应

为提高HZSM-5催化乙酸环己酯水解反应生成环己醇的选择性,筛选得到了离子液体[BMIm]Br助剂。发现[BMIm]Br可抑制乙酸环己酯热分解副反应的发生,大幅度提高环己醇选择性。并且,[BMIm]Br可与HZSM-5发生离子交换反应,释放出的H⁺可促进乙酸环己酯水解反应的发生。在优化的条件下,[BMIm]Br辅助HZSM-5催化乙酸环己酯水解反应转化率为87.5%,环己醇选择性为97.3%。考察了[BMIm]Br和HZSM-5的重复使用性。前者具有较好的稳定性,而HZSM-5活性随循环使用的次数增加而下降。这是由于HZSM-5的骨架铝含量在反应中逐渐降低,导致Br?nsted酸中心数量减少,因此其催化活性逐渐降低。     

Surface-initiated RAFT polymerization of p (MA POSS-co-DMAEMA+) brushes on PDMS for improving antiadhesive and antibacterial properties

Poly (dimethylsiloxane) (PDMS) silicones, as a common intraocular lenses material, often lead to the happen of posterior capsule opacification due to the adhesion and reproduction of residual human lens epithelial cells (HLECs) on the posterior capsule after surgery. Bacterial infection is a potentially catastrophic complication of cataract surgery, which occurs within several days after implantation of the lens. A novel poly (methacrylisobutyl polyhedral oligomeric silsesquioxane-co-2-(dimethylamino)-ethyl methacrylate) (p (MA POSS-co-DMAEMA)) brush was synthesized by reversible addition–fragmentation chain-transfer (RAFT) polymerization. After being quaternized treatment by 1-bromo-heptane, p (MA POSS-co-DMAEMA⁺) brushes with bactericidal function were obtained. The optical transmission of the brushes functionalized PDMS was better than p (DMAEMA⁺) coating modified PDMS, which may be due to the similar chemical composition of MA POSS and PDMS. Measurements of water contact angle, spectroscopic ellipsometry, and atomic force microscope were used to characterize hydrophilicity, thickness, and morphology of the brushes. Results revealed that brushes rendered PDMS surface more hydrophilicity and higher roughness. Adherences of bovine serum albumin and HLECs on the p (MA POSS-co-DMAEMA⁺) brushes were significantly reduced due to the hydrophilic property and cytotoxicity of the brushes. Bactericidal activity of the brushes, measured by shake-flask culture and LIVE/DEAD bacterial viability kit staining methods, was remarkably effective against S. aureus owing to the component of p (DMAEMA⁺).     

N-[1-(4-甲氧基)环己基]哌啶的合成研究

报道了一种合成N[1-(4-甲氧基)环己基]哌啶的新方法,与原来的工艺相比较,避免了剧毒物NaCN的使用,操作更简洁,总收率由33%提高至53.3%。     

Efficient Light‐Emitting Devices Based on Phosphorescent Polyhedral Oligomeric Silsesquioxane Materials

Synthesis, photophysical, and electrochemical characterizations of iridium‐complex anchored polyhedral oligomeric silsesquioxane (POSS) macromolecules are reported. Monochromatic organic light‐emitting devices based on these phosphorescent POSS materials show peak external quantum efficiencies in the range of 5–9%, which can be driven at a voltage less than 10 V for a luminance of 1000 cd m^?2. The white‐emitting devices with POSS emitters show an external quantum efficiency of 8%, a power efficiency of 8.1 lm W^?1, and Commission International de'lÉclairage coordinates of (0.36, 0.39) at 1000 cd m^?2. Encouraging efficiency is achieved in the devices based on hole‐transporting and Ir‐complex moieties dual‐functionalized POSS materials without using host materials, demonstrating that triplet‐dye and carrier‐transporting moieties functionalized POSS material is a viable approach for the development of solution‐processable electrophosphorescent devices.     

聚甲基苯基硅氧烷微球对聚碳酸酯性能的影响

研究了不同含量聚甲基苯基硅氧烷微球(PMPSQ)对聚碳酸酯(PC)阻燃性能、加工性能和力学性能等的影响。结果表明,随着 PMPSQ 含量的增加,冲击强度呈先上升后下降的趋势,PMPSQ 含量为5%时,冲击强度达到最大值,较空白 PC 提高了71.5%。PC 的阻燃性能随 PMPSQ 含量的增加而升高,当 PMPSQ 含量为5 %时,氧指数达到32.1%,较空白 PC 提高了23.0%。随着 PMPSO 含量的增加,PC 的玻璃化转变温度(T_g)逐渐下降,PMPSQ 含量为5%时,PC 的 T_g 从空白时的144.5℃降低至139.1℃。流变学分析表明,PMPSO 的加入可以有效降低 PC 的表观黏度,改善材料的加工性能。     

Chitosan–Oligo(silsesquioxane) Blend Membranes: Preparation, Morphology, and Diffusion Permeability

Preparation of the blend chitosan (CHI) membranes containing polyhedral oligomeric silsesquioxane (POSS) derivatives was investigated. POSS derivatives such as (3-aminopropyl)isobutyl-POSS (amino-POSS), [2-(3,4-epoxycyclohexyl)ethyl]isobutyl-POSS (epoxy-POSS), and octa(tetramethylammonium)-POSS were used. The blend CHI–amino-POSS membranes were predicted to be the most porous due to having the weakest interactions between the components in the blends. The CHI–epoxy-POSS blend membranes were assumed to be more dense owing to chemical binding of the chitosan amino groups with the epoxy groups of POSS. Studies of membrane morphology and diffusion permeability support these predictions.     

新一代高性能POSS-聚合物材料

描述了多面体聚硅倍半氧烷（Polyhedral Oligomeric Silsesquioxane,POSS)单体的结构与性能,POSS单体改性聚合物在塑料工业,航空与空间等领域的应用现状与前景,并对POSS单体合成技术,成本,POSS单体一步形成串凳式,悬笼式和笼－笼连接式结构作了综合评述。