Volatile evolution from room temperature cured polysiloxane rubber induced by irradiation with He ions

A room temperature cured polysiloxane rubber (Rhodorsil RTV5370) has been irradiated using an accelerated beam of He²⁺ ions. Such an irradiation simulates the effects of large alpha radiation doses. A mass spectrometer linked directly to the sample chamber allowed the analysis of volatile species evolved as a result of exposure. The polydimethylsiloxane rubber showed high resistance to radiation damage when exposed to He²⁺ ions at doses up to 3.5 MGy. At higher doses, the cyclic hexamethylcyclotrisiloxane was evolved and is indicative of damage to the main chain. The cyclic octamethylcyclotetrasiloxane was only observed at very high doses (10 MGy and above) and is indicative of significant head-to-tail unzipping reactions. Methane, benzene and carbon dioxide were the three main gases evolved. The ratio of phenyl (2%) to methyl groups (93%) within RTV5370 rubber is very small but the amount of benzene evolved was found to be significant. The results suggest that the aromatic groups within the rubber appear to have a much greater susceptibility to radiation induced volatile evolution than other groups making up the polymer structure. In addition, the depletion of phenyl groups (from the reduction in evolution of benzene) from the irradiated zone corresponds to an increase in damage of the siloxane linkages (from the increased evolution of octamethylcyclotetrasiloxane) suggesting the aromatic groups offer a protective action from the incident radiation.     

The Preparation of the Carbosilane Dendrimers with Pentafluorophenyl Groups

Dendrimers as intriguing macromolecules possess potential in phase transfer catalysis, hosts-guest chemistry, controlled release drugs or might serve as recyclable extracting agents1,2,3. The fluorine-containing dendrimers can be used as low surface-energ…     

6-tert-Butyldimethylsilyl-2,3-dimethyl-α-, β-, and γ-cyclodextrins,dissolved in polysiloxanes,as chiral selectors for gas chromatography. Influence of selector concentration and polysiloxane matrix polarity on enantioselectivity

The enantioselectivity of three chiral selectors, 6-t-butyldimethyl-silyl-2,3-dimethyl-α-, β- and γ-cyclodextrin (TB-α-CD, TB-β-CD, TB-γ-CD), are compared and discussed for a range of chiral test compounds. TB-β-CD in particular offers high enantioselectivity for a variety of chiral compounds and has the special property of excellent solubility in different alkylpolysiloxanes, including the weakly polar variety, because of its weak self-association. To investigate the influence of the polarity of polysiloxane matrices this selector can be used at a wide range of concentrations in the most suitable polysiloxane matrices and at low separation temperatures without impairment of resolution by peak broadening and symmetry distortion.     

水性聚硅氧烷和聚乙烯醇复合物制备及其作为皮肤屏障材料的性能北大核心CSCD

皮肤作为人体最外层的器官,容易遭受损伤,构建能够为皮肤提供保护作用的屏障材料具有非常重要的意义。基于皮肤屏障材料性能要求,将亲水改性的聚硅氧烷(PSI)和聚乙烯醇(PVA)相结合,通过原位Ca2+离子交联构建了一种复合多功能的皮肤屏障材料PSI-PVA。研究表明,该材料具有较好的干态和湿态力学性能,以及较好的皮肤相容性、可清洗性、亲水性、透气性、可修饰性和生物相容性。当PVA质量分数为20%时,溶胀率可达149%;随着PVA用量的增加,材料的清洗容易程度提高;紫外吸收剂羟基苯甲酮修饰后,材料的紫外光(200~400 nm)透过率在20%以下,在材料的保护下,小鼠胚胎成纤维细胞(NIH 3T3)在UVB(311 nm)照射后具有较高的存活率(71%)。因此,PSI-PVA可以满足皮肤屏障材料多项性能需求,在皮肤保护和受损修复等领域具有较好的应用前景。     

Sphere-to-rod transition of short-chain PEO-b-PDMS-b-PEO in aqueous solution induced by copolymer concentration

A short-chain triblock copolymer EO9-DMS7-EO9 was synthesized by coupling reaction of allyl-terminated poly（ethylene oxide） and Si-H-terminated poly（dimethylsiloxane）. The structure and purity of synthesized copolymer was carefully characterized. Self-assembly behavior of EO9-DMST-EO9 triblock copolymer in water was investigated. And it was found that along with the increase of copolymer concentration, morphology of self-assembled aggregates transits from sphere to rod. A plausible understanding of the morphology transition for the investigated triblock copolymer was proposed.     

聚γ-氨丙基硅氧烷钯、钼双金属催化剂的合成、加氢活性及其XPS研究

本工作合成了四种不同N/Pd摩尔比的聚γ-氨丙基硅氧烷钯、钼双金属催化剂,它们的加氢活性与相应的钯、钼单金属催化剂的混合物相比差别不大,但是,由于钼的加入,提高了单金属钯催化剂的加氢活性。XPS分析表明,有一部分N与PdCl_2及MoCl_x发生络合,而且Pd-Cl键和Mo—Cl键依然存在,催化剂中Pd的价态为正2价,Mo的价态为正5或6价。     

含偶氮苯基侧基聚硅氧烷的合成及光致变色性

含偶氮苯基侧基聚硅氧烷的合成及光致变色性张其震，张静智，王艳（山东大学化学系济南２５０１００）（山东大学环境科学中心济南２５０１００）关键词聚硅氧烷，光致变色，光异构化，量子产率将光致变色性和液晶性化合物结合可得到新的多功能高分子材料，Ｒｉｎｇｅｄｏ...     

聚硅氧烷/丙烯酸酯核/壳复合胶乳的粒径分布与成核机理

通过种子乳液法合成出具有高有机硅含量核 壳结构的聚硅氧烷 丙烯酸酯复合粒子 .研究了聚合方法、乳化剂浓度、引发剂浓度、单体滴加速度等工艺条件对复合乳液粒径尺寸、分布与形态的影响 ,并对复合乳液的成核机理进行了探讨 .研究表明 ,乳化剂浓度对乳液粒子的粒径分布和形态、结构有显著影响 ,引发剂浓度增加将使粒子粒径减小 ;相对一次投料法 ,种子乳液法生成的粒子分布窄 ,具有明显核壳结构 ,通过壳层单体滴加速度可以控制粒子的粒径尺寸和分布 ;而壳层丙烯酸酯聚合物主要是在聚硅氧烷种子表面的“过渡层”聚合、富集而成 .     

有机在同聚物改性环氧树脂的方法与机理

综述了有机硅高聚物改性环氧树脂的各种改性方法、反应机理以及改性机理的研究进展。     

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

Based on the synthesis and characterization of side-chain liquid crystal polysiloxanes containing p-methoxyl phenyl benzolate, the homogeneous electrorheological (ER) liquid and its smart damper were fabricated. The properties of the homogeneous ER liquid and its smart damper were tested. The results indicated that the homogeneous ER liquid with significant ER effect at room temperature is obtained by mixing the side-chain liquid crystal polysiloxanes containing p-methoxyl phenyl benzolate and silicone oil. Its shear stress reached 1550Pa at electrical field strength (E) of 2.2 kV/mm and shear rate of 300 s-1. The damping forces of the smart damper based on the homogeneous ER liquid enhanced if E and oscillation frequency increased. Consequently, an effective way for semi-active control using the smart damper based on the homogeneous ER liquid was put forward to reduce the seismic responses of the structures.