聚硅氧烷/钛溶胶光催化复合膜的光催化降解作用

以锐钛型的钛溶胶和粉体Ti O2为光催化材料,以聚硅氧烷(PDMS)和聚丙烯酸酯(PA)为黏合剂,制得相应的光催化复合膜.通过X-射线衍射分析、粒度分析、电镜观察等手段比较2种Ti O2颗粒的晶型及其在有机介质和复合膜中的分散状态,通过光学显微观察、载体降解失重评估、染液吸光度测定等方式考察Ti O2对两类黏合剂和酸性品红6B染料分子的光催化降解作用.发现溶胶-凝胶法可制得结晶程度较高的锐钛型钛溶胶,且所制颗粒晶粒更小、与有机介质和黏合剂的相容性更好,在复合膜中分散更均匀,因而更易光催化降解接近复合膜的染料分子,但同时也更易老化降解以低键能C—C键为主链的常规碳链黏合剂.而聚硅氧烷以高键能的Si—O键为主链,其抵御光催化所产高能自由基的氧化-还原作用的能力更强,是一种理想的光催化有机载体.通过聚硅氧烷与钛溶胶的有效复合,可在保证复合膜稳定性的同时赋予其更强的光催化降解作用.     

A robust and efficiently reprocessable poly(dimethylsiloxane) elastomers enhanced by self-catalysis Zn(II)-ligand bonds and silyl ethers

In recent years, as an emerging dynamic bonding, silyl ether linkages have been concerned and applied. However, the reprocessability of vitrimers based on it is far from satisfactory because of the inactive dynamic exchange reaction. At the same time, the mechanical properties of polysiloxane elastomers are poor because of the high flexibility of polysiloxane molecular chains and weak intermolecular forces. Herein, we have successfully synthesized a PDMS elastomer incorporating Zn(II)-amine coordination bonds as sacrificial units, which are crosslinked through dynamic silyl ether linkages. Importantly, the presence of Zn ions promotes the exchange between the silyl ether linkages and hydroxyl groups. The elastomers exhibited excellent mechanical properties (35 times improvement in toughness) and outstanding reprocessability. The mechanical property recovery of the PDMS elastomers reached approximately 90% after four reprocessing cycles. Meanwhile, small-molecule simulation experiments were conducted to verify the significant catalytic effect of Zn (II) ions as Lewis acid catalysts on the exchange reaction of silyl ether linkages and hydroxyl groups. In a word, this work provides a facile strategy to simultaneously enhance the mechanical properties and reprocessing performance of silyl ether-linked polysiloxane elastomers.     

光致变色液晶高分子的研究(Ⅰ)─含胆甾介晶基无侧链聚硅氧烷及其单体的液晶行为

用POM、DSC和WAXD研究了十一烯酸胆甾酯及含胆甾介晶基元侧链聚硅氧烷的液晶行为。单体呈现明甾相的油条及螺旋织构,单致变近晶相的扇形织构和固-固相变。均聚物显示S_A相的扇形织构。     

B(C6F5)3在有机化学及高分子化学中的应用研究进展

B(C6F5)3与传统的Lewis酸相比,具有化学性质稳定、酸性强、使用方便等优点,被称为非传统的Lewis酸。B(C6F5)3的应用领域已经从最初的烯烃聚合共催化剂向有机化学及高分子化学的其它各个领域发展。B(C6F5)3催化的反应与传统Lewis酸催化的反应在反应机理及反应结果上均有很大的不同。本文主要综述B(C6F5)3近年来在有机化学及高分子化学中的应用研究成果。     

A Nitrite Biosensor Based on Coimmobilization of Nitrite Reductase and Viologen‐Modified Polysiloxane on Glassy Carbon Electrode

Copper containing nitrite reductase (Cu‐NiR) and viologen‐modified sulfonated polyaminopropylsiloxane (PAPS‐SO₃H‐V) were co‐immobilized on glassy carbon electrode (GCE) by hydrophilic polyurethane (HPU) drop‐coating, and the electrode was tested as a reagentless electrochemical biosensor for nitrite detection. The newly synthesized PAPS‐SO₃H‐V as an electron transfer (ET) mediator between electrode and NiR was effective, and could be effectively immobilized in HPU membrane. The NiR and PAPS‐SO₃H‐V co‐immobilized GCE used as a nitrite biosensor showed the following performance factors: sensitivity=12.0 nA μM^?1, limit of detection (LOD)=60 nM (S/N=3), linear response range=0–18 μM (r²=0.996) and response time (t_90%)=60 s, respectively. Lineweaver–Burk plot shows that apparent Michaelis–Menten constant (K is 101 μM. Storage stability of the sensor is 51 days (80% of initial activity) in condition of storing in ambient air at room temperature. The sensor showed a relative standard deviation (RSD) of 3.2% (n=5) even in condition of injection of 1 μM nitrite. Interference study showed that common anions in water sample such as chlorate, chloride, sulfate and sulfite do not interfere with the nitrite detection. However, nitrate interfered with a relative sensitivity of 80% due to inherent character of the enzyme used.     

Synthesis, characterization and properties of the polysiloxane-based episulfide resin

The polysiloxane episulfide resin (PSER) was synthesized through replacement of the oxygen atoms in 1,3,5,7-tetra-(3-glycidoxypropyl) tetramethylcyclotetrasiloxane (TGCS) with sulfur atoms using potassium thiocyanate (KSCN). It was characterized by FT-IR, ¹H NMR, MS and elemental analysis. The PSER resin was a low viscosity liquid, stable at room temperature. The polysiloxane episulfide resin was very reactive: a mixture of PSER and isophorondiamine gelated in a few seconds at room temperature. When m-phenylenediamine (m-PDA) or 2-ethyl-4-methylimidazole (2E4MZ) was used as curing agent, PSER exhibited higher reactivity compared with the parent polysiloxane epoxy resin. The reaction heat of the PSER resin was much lower in comparison with TGCS. The cured polysiloxane episulfide resin showed higher glass transition temperature and much lower water absorption, while the thermal stability was lower. It was found that methylhexahydrophthalic anhydride (MeHHPA) is not effective for curing the episulfide resin, although it is commonly used for curing epoxy resins.     

Surface hydrophobization of polyester fibers with poly(methylhydro-dimethyl)siloxane copolymers: Experimental design for testing of modified nonwoven materials as oil spill sorbents

This paper reports on the hydrophobization of polyester fibrous nonwoven with poly(methylhydro-dimethyl)siloxane copolymers in order to produce water-repellent sorbents for oil spill cleanup. Polysiloxane copolymers were first synthesized and characterized prior to be used as hydrophobization agents. The produced hydrophobic sorbents were characterized by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX); infrared spectra (FTIR) and water-contact angle measurements (WCA). Nonwoven sorbents were evaluated for oil sorption in pure oil bath and in the presence of water (W-test). A statistical experiment design was employed for materials testing and the development of data-driven models. The optimal hydrophobic nonwoven yielded maximal sorption capacities equal to 5.52 g/g and 10.03 g/g for dodecane and motor oil uptake, respectively. The mechanism of oil attachment on polymeric fibers was investigated by optical microscopy revealing a key role of inter-fiber voids for oil retention. Centrifugation tests demonstrated a high recycling ability of spent nonwoven sorbents.     

正离子光固化聚硅氧烷的合成及其环氧树脂复合固化膜的性能

以含氢聚硅氧烷(PMHS)分别与甲基丙烯酸六氟丁酯(HFMA)和烯丙基缩水甘油醚(AGE),经氯铂酸催化硅氢加成反应将甲基丙烯酸六氟丁酯和烯丙基缩水甘油醚引入聚硅氧烷的侧链,合成了3种含氟量不同的含氟代烃侧基/环氧侧基聚硅氧烷(EFPS),用FTIR、1H-NMR和13C-NMR进行了结构表征,将这类聚硅氧烷与环氧树脂...     

Investigating the ageing behavior of polysiloxane nanocomposites by degradative thermal analysis

The ageing behavior of novel polysiloxane nanocomposite elastomers is reported. A series of model polysiloxane nanocomposites has been prepared incorporating the montmorillonite nanoclay Cloisite 6A. The nanoclay dispersion has been characterized with X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). TGA has been utilized to study the effects of ageing on the non-oxidative stability of the nanocomposite systems. The complex evolution of volatiles that occurs during ageing has been studied using Sub-Ambient Thermal Volatilization Analysis (SATVA). Results indicate that significant chemical changes take place within the nanocomposites upon ageing; acid catalyzed hydrolysis, chain backbiting and recombination reactions are re-structuring the polymer-filler network into a more thermodynamically stable form.     

用含苯甲酸甲氧基苯酯的聚硅氧烷组成均相电流变液及其智能阻尼特性的研究

在合成并表征含苯甲酸甲氧基苯酯的侧链液晶聚硅氧烷高分子的基础上,制备了均相电流变(ER)液及其智能阻尼器.测试了ER液及其智能阻尼器在室温下的性能.结果表明,用含苯甲酸甲氧基苯酯的侧链液晶聚硅氧烷能组成在室温下表现出较强ER活性的均相ER液,它在外加电场E=2.2kV/mm,剪切速率为300s-1时,剪切应力达到1550Pa;增加E和振动频率,均相ER液智能阻尼器的阻尼力均增加,阻尼效果提高.