Synthesis of fluorine-containing organosilicon copolymers and their use for the preparation of stable hydrophobic coatings based on the epoxy binder

A series of novel fluorine-containing organosilicon copolymers was synthesized in an excess of acetic acid. The efficiency of their use as hydrophobic agents for epoxy film-forming materials was shown.     

Benzoxazine siloxanes as modifiers of epoxy resins for coatings

Coatings based on epoxy resin ED-20 modified with organosilicon 1,3-benzoxazines at a concentration of 1–10 wt % have been prepared and studied. According to the DSC data, the curing temperature of the modified compositions falls in the range of 130–150°C. It has been shown that the use of benzoxazine siloxanes as modifying additives significantly improves the adhesion and anticorrosive properties of epoxy coatings.     

Shelf-Life Studies on B-Stage Novolac Epoxy Glass Mica Tapes

Activation energy for the curing process of epoxy glass mica tape has been experimentally determined from differential scanning calorimetric measurements and found to be 20 kcal/ mol. Thermochemical calculation shows that the rate controlling step is the dissociation of the C-O bond in the epoxide leading to ring opening and its subsequent reaction with amine hardener. Shelf life has been determined from the measurement of the enthalpy loss corresponding to the curing during the aging process. The kinetics of the aging process also yields an activation energy of 20 kcal/mol which corresponds to the slow curing of the epoxy resin.     

有机硅改性丙烯酸环氧单酯光-热混杂固化体系的表面性能

以有机硅改性丙烯酸环氧单酯为树脂配制了一系列紫外光-热混杂固化体系.通过FTIR表征了光-热固化过程双键和环氧特征吸收峰的变化.研究了不同的稀释剂对光固化和光-热混杂固化膜的凝胶率、吸水率、表面水接触角等性能的影响,并用能谱仪(EDS)测试了固化膜表面硅元素的含量.结果表明:光固化膜的凝胶率低于86.5%,而光-热混杂固化膜的凝胶率在97.0%左右.与丙烯酸环氧单酯光-热固化体系相比,有机硅改性丙烯酸环氧单酯光-热固化膜的表面水接触角有显著提高,由62.53°提高到99.27°,EDS测试也表明有机硅有富集于固化膜表面的特性.     

Electrical and positron annihilation study on epoxy and epoxy acrylate composites

Epoxy acrylate resin was prepared by endcapping the acrylic acid to epoxy resin backbone in the presence of triphenyl phosphene as catalyst. The structure was elucidated by IR and NMR spectroscopy. Epoxy and epoxy acrylate composites were prepared by mixing different concentrations of mica, magnesium hydroxide and calcium silicate with each epoxy/hardener and epoxy acrylate/styrene mixtures, respectively. The permittivity ε′, dielectric loss ε′′ and loss tangent tan δ were measured for these composites in the frequency range (10²-10⁶ Hz) and at 30 °C. The data obtained were analyzed into two absorption regions related to Maxwell-Wagner effect and to some local molecular motions rather than the main chain motion. The higher values of ε′ and the lower values of tan δ given for the composites containing the epoxy acrylate resin indicate some improvement in the dielectric properties when compared with those containing the epoxy resin. The effect of filler type and filler content on the positron annihilation lifetime and its intensity as well as S-parameter for epoxy and epoxy acrylate composites were also studied. The high values of S-parameter noticed by with increasing filler content indicates some increase in free electrons which lead to an increase in electrical conductivity. The highest value of hardness was obtained in the case of calcium silicate followed by mica and magnesium hydroxide.     

有机硅改性UV固化水性环氧树脂的研究

以环氧树脂E-51、甲基三乙氧基硅烷为原料,用接枝共聚的方法合成了有机硅改性水溶性UV固化环氧树脂,该方法有效地改善了环氧树脂的柔韧性、水溶解性,提高了成膜物的机械性能,其拉伸强度达到53.5 MPa,断裂伸长率为46.5%,耐冲击性大于50 kg/cm。通过红外光谱、热重分析表征产物的结构和性能,结果表明,有机硅已经成功接枝到环氧树脂的分子上。有机硅改性后环氧树脂在400℃的分解率由之前的60%降至40%。文章同时讨论了有机硅改性水性UV固化环氧树脂合成中反应温度、有机硅种类以及加入量等对UV固化水性环氧树脂成膜物的附着力、耐水性及耐碱性的影响,以此获得最佳反应条件:质量分数为14.4%的甲基三乙氧基硅烷与羧酸改性的环氧树脂在90℃下反应5～6 h。     

疏水蛋白在云母表面的吸附

采用分子动力学模拟方法研究了疏水蛋白(HFBI)在亲水云母表面的吸附过程.通过6组平行的分子动力学模拟得到了2种不同的稳定吸附结构,即通过N端和通过亲水的α螺旋与表面吸附,得到了5种吸附残基.进一步用自适应偏置力方法计算了所有吸附残基与表面的结合自由能.结果表明,残基Lys是吸附过程的关键残基,即当HFBI通过含有Lys残基的α螺旋与云母表面作用时,其吸附构象最稳定.静电作用是吸附过程的主要驱动力.在该吸附结构中,HFBI的疏水面暴露在溶液中,有效降低了云母表面的润湿性.     

Radical induced cationic frontal polymerization as a versatile tool for epoxy curing and composite production

Radical induced cationic frontal polymerization (RICFP) is an extremely powerful and elegant alternative curing technique that allows cationic bulk curing of epoxy resins with very little energy consumption, as well as curing in compartments that are not readily accessible. We recently introduced a bisphenol‐A diglycidylether (BADGE) based system that allows the bubble‐free photocuring of this widely used epoxy resin. In this article, we describe the high storage stability and possibilities to influence the curing speed via the initiator concentrations of different formulations. These properties allow the adjustment of the frontal polymerization to ones need. We also show that the (thermo)mechanical and electrical properties of frontal cured epoxy polymers compares favorably with those of state of the art material. Finally, different strategies to overcome the challenges on producing epoxy resin based mica composites via RICFP are presented. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3751–3759     

PM-IRRAS investigation of self-assembled monolayers grafted onto SiO2/Au substrates

Polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) was used to characterize self-assembled monolayers (SAMs). Novel ester-terminated organosilicon coupling agents possessing a trialkoxysilyl headgroup and a urea group in the linear alkyl chains (4) were synthesized and grafted onto SiO(2)/Au substrates (SiO(2) film of 200 ? thickness deposited on gold mirror). This composite substrate allowed the anchoring of SAMs and preserved the high reflectivity for infrared radiation. PM-IRRAS spectra with very high signal-to-noise ratios have been obtained in the mid-infrared spectral range allowing monitoring of the grafted SAMs. Quantitative analysis of the measured signal is described to compare PM-IRRAS and conventional IRRAS spectra. This quantitative analysis has been validated since the band intensities in the corrected PM-IRRAS and conventional IRRAS spectra are identical. Orientation information on the different functional groups has been obtained comparing the corrected PM-IRRAS spectrum with the one calculated using isotropic optical constants of ester-terminated organosilicon coupling agents 4. The carbonyls of the urea groups are preferentially parallel to the substrate surface favoring intermolecular hydrogen bonding and consequently a close packing of the molecules attached to the surface. By contrast, the alkyl chains present gauche defects and are poorly oriented.     

A novel insight into the inductive effect in silicon chemistry

A revision of quantitative literature data for the reactivity of organosilicon compounds in light of conceptions stemmed from organic chemistry has been carried out. It has been found that in structure-reactivity analysis for organosilicon compounds, differently of carbon compounds, the inductive effect of substituents, at least in nucleophilic displacement reactions at silicon, must be expressed by two terms involving that for electronegativity. A protocol for the correlation analysis in organosilicon chemistry is now available.     

Epoxy ketones as versatile building blocks in organic synthesis

The major advances made in the functionalisation of racemic and optically active epoxy ketones where one or several stereogenic centres are either preserved or modified are reviewed. Some relevant applications to the synthesis of natural products and biologically active compounds are also described.     

Synthesis and properties of polymeric materials prepared by anionic polymerization of epoxy oligomers

The kinetics of anionic polymerization of epoxy oligomers of different functionalities in the presence of imidazoles was studied. Polymers based on the chosen systems, exhibiting high elastic and deformation characteristics at compression in a wide temperature range, and also resistance to heat and water, were synthesized. The epoxy compounds exhibit high adhesion to aluminum, preserved at elevated temperatures (150°C).     

Thermal stability and flammability of silicone polymer composites

Silicone polymer composites filled with mica, glass frit, ferric oxide and/or a combination of these were developed as part of a ceramifiable polymer range for electrical power cables and other high temperature applications. This paper reports on the thermal stability of polymer composites as determined by thermogravimetric techniques, thermal conductivity and heat release rate as measured by cone calorimetry. The effects of fillers on thermal stability and flammability of silicone polymer are investigated. Of the fillers studied, mica and ferric oxide were found to have a stabilising effect on the thermal stability of silicone polymer. Additionally, mica and ferric oxide were found to lower heat release rates during combustion, but only mica was found to increase time to ignition.     

具有生物活性的有机硅化合物研究近况

生物有机硅化合物的研究进展迅速,而且越来越受到人们的重视。实际上,它是有机硅化学的一个新的分支。本文对有机硅化合物的毒理学、有机硅药物化学以及有机硅农药作了简要的论述。     

多级孔TS-1用于油酸甲酯高效绿色环氧化

当今时代,资源短缺、环境污染等问题日益严峻,生物质资源化学转化利用成为各国研究重点,以生物质资源代替化石资源、以生物基材料代替石化材料,为发展绿色经济、循环经济奠定了基础.植物油资源由于其广泛的可获得性、固有的生物可降解性、低成本及突出的环境效益受到广泛关注.其中,环氧化的植物油作为可再生原材料应用于生产热塑材料的增塑剂和稳定剂、生物润滑油、涂料、粘合剂、化妆品及各种聚合物材料 (聚酯、聚氨酯、聚酰胺等).目前,工业上生产环氧化植物油通常采用 Prilezhaev 过程,即在无机强酸如 H2SO4,HCl,HNO3等的催化作用下,过氧化氢与甲酸或乙酸作用原位生成过氧甲酸或过氧乙酸作为环氧化试剂用于环氧化反应.但就该反应过程而言,强酸的存在会带来一系列问题:(1) 强酸的存在容易引发一系列副反应,如环氧环开环生成二醇、二聚物等; (2) 产物分离问题,反应完毕后产物需经碱洗、水洗和减压蒸馏才能得到最后产品,工艺过程复杂且可能造成环境污染,不符合绿色化学理念; (3) 强酸存在引起的设备腐蚀问题.因而开发新型高效的催化技术降低生产成本,解决生产过程中的污染问题,实现植物油的绿色高效利用,是我们当前迫切要解决的问题.寻找安全无污染且具有高效催化性能的非均相催化剂也迫在眉睫.因此,各过渡金属如 MoIV,WVI,NbV和 TiIV复合物催化剂得到广泛研究.其中,钛硅分子筛 TS-1 由于其良好的稳定性及优异的环氧化催化性能受到关注,然而其狭窄的孔道尺寸使得它在大分子反应物参与的反应中受到显著的扩散限制,因而需合成含有介孔及大孔的多级孔 TS-1 用于植物油环氧化反应中.本课题组多年从事钛硅分子筛的制备及催化氧化研究工作.本文以聚季铵盐-6 作为介孔模板剂合成了多级孔TS-1(HTS-1),将其作为催化剂,油酸甲酯作为模型化合物,H2O2作为氧化剂,系统研究了反应条件 (H2O2与双键摩尔比、氧化剂浓度与用量、反应温度与时间) 对油酸甲酯环氧化反应的影响.采用响应曲面分析法 (RSM) 优化反应条件,获取环氧化油酸甲酯的最大收率,并对各因素对油酸甲酯环氧化影响的显著性及各因素之间的交互作用进行探究.结果发现,H2O2与双键摩尔比及催化剂用量对油酸甲酯环氧化的影响较大,在优化的反应条件下环氧化产物的收率可高达 94.9%.而HTS-1 表现出的优异催化性能主要归结于其良好的疏水性能和高活性且可供大分子接触反应的钛物种.     

某些新的氟代有机硅化合物的合成

本文用含硅氢键化合物与含双键的氟化合物的加成反应,制备了一系列未见报导的含氟有机硅化合物。在用氯丙烯与2,2,3,3-四氟丙醇制2,2,3,3-四氟丙基烯丙醚时,对方法进行了改进,提高了产率。本文还报道了含氟有机硅聚合物方面的工作。     

新型固定化方法－－环氧胺树脂及硅树脂生物包埋

在生物包埋技术的研究过程中，人们发现生物功能可以融合并保存于聚合物基 质中，继溶胶凝胶生物包埋法以后，目前以发展了许多非溶胶凝胶聚合物用于蛋白 质的固定化，此类聚合物包括环氧胺树脂，硅树脂，聚乙烯塑料和聚氨酯泡沫材料 等。迄今为止，人们已成功地将多种酶包埋其中，加上原有的溶胶凝胶包埋物。这 些生物复合体为生物物质的固定化及在生物传感器和生物催化剂中的应用提供了一 个强有力的工具，此外，作为具有生物活性且防污染的聚合物，它们还有望应用于 环境，食品以及医药行业，尽管尚处于发展阶段，但是这些生物复合体将为高效生 物固定化提供一种新的手段，将具体介绍其中最受关注的环氧胺树脂和硅树脂。     

Organosilicon polymers for lithographic applications

Organosilicon polymers have found many uses in the electronics industry in the last twenty-five years due to their low dielectric constant and water-repelling properties. These uses include insulators and encapsulating materials for electronic parts. More recently, siloxanes are being incorporated into polyimides for the purpose of increasing the water resistance, improving mechanical properties and preventing atomic oxygen attack of polyimides. Only in the last few years, some uses of organosilicon polymers in lithography have been reported. In this paper, a review of these uses will be presented and the requirements for organosilicon materials in lithography applications will be outlined.     

Heterophase polymerization of styrene in the presence of organosilicon compounds of various natures

The heterophase polymerization of styrene has been carried out in the presence of surfactants—organosilicon compounds with different solubilities in aqueous and styrene phases and surface activities at the interface. It has been demonstrated that the stability of polymer suspensions prepared with water-insoluble organosilicon compounds is much higher than that in the presence of organosilicon surfactants soluble in organic and aqueous phases. In the former case, suspensions with narrower particle-size distributions are produced. The stability of polymer microspheres prepared at various monomer-to-water volume ratios has been tested. An increase in the monomer concentration above 25 vol % leads to the loss of system stability.     

Epoxy and hydroxy functional polyolefin macromonomers

Methods for preparing saturated polyolefin oligomers with Si(SINGLE BOND)H, epoxy groups, and with dihydroxy groups have been developed. Anionic polymerization of butadiene, then termination of the chains with chlorodimethylsilane leads to controlled molecular weight oligomers with silane functionality, and wherein the microstructure can be tailored. Hydrogenation of these materials proceeds smoothly using colloidal nickel catalysts to yield the corresponding saturated materials, which are stable to conditions used for melt polyesterifications. Hydrosilation of allyl glycidyl ether with the Si(SINGLE BOND)H end groups produces epoxy functional oligomers, and subsequent hydrolysis of the epoxy rings yields oligomers with a dihydroxy group at one end. Melt copolymerization of the olefin macromers with 1,4-butanediol and 1,4-dimethylcyclohexanedicarboxylate in the presence of titanium isopropoxide affords poly(ester-g-olefin) graft copolymers. These copolymers are under study as model interfacial agents for polyester/polyolefin blends and as suspension agents for polyester particles in nonpolar media. © 1996 John Wiley & Sons, Inc.