硅橡胶新硫化体系的研究

本文介绍一种硅橡胶新硫化体系,即利用Diels-Alder反应使聚硅氧烷进行交联。所用生胶为含乙烯基的高分子量聚甲基硅氧烷,所用交联剂(硫化剂),即双烯体,系含有环戊二烯基的有机硅化合物。所得弹性体的物理机械性能达到高强度硅橡胶水平。     

冠醚-聚硅氧烷的研究现状与展望

本文叙述了冠醚-聚硅氧烷,即含有冠醚基团的聚硅氧烷.硅胶或二氧化硅表面接枝冠醚的合成与应用的研究现状与展望.     

几种β-二酮化合物互变异构体的光谱性质研究

合成了5种不同结构的β-二酮化合物,采用电喷雾质谱、紫外光谱、红外光谱和核磁共振法对其结构进行表征,并讨论了它们的酮式-烯醇式互变异构现象.结果表明,β-二酮分子内酮式-烯醇式的互变异构平衡明显受取代基影响,它们的酮式-烯醇式互变异构体含量完全不同.在固态和CDCl3溶液中,其中2种β-二酮化合物(a1,a2)中主要以烯醇形式存在,仅含有少量的酮式结构;而2种α-取代β-二酮(b1,b2)由于烯醇异构体的空间位阻效应,不能以分子内氢键形成烯醇六元环,全部以酮式结构形式存在;另外,由于强吸电子基团-CF3的作用,使得β-二酮(c)全部以烯醇形式存在.     

环二硅氨烷化学的研究 Ⅰ.主链含环二硅氨烷硅橡胶的合成和性能

本文叙述了在主链中含有环二硅氨烷的线型聚硅氧烷的合成,所得到的聚合体无论在聚合或贮存时都不会发生交联,这个结果完全不同于文献曾经报导的类似结构的聚合体的实验结果。 由聚合体 (?)得到的橡皮具有很好的力学性能和好的水解稳定性,其耐热性接近于卡硼烷硅橡胶。在350℃的热空气下老化24小时,仍能保持伸长率100％和抗拉强度80公斤/厘米~2。     

新型6,6-取代芳基富烯的合成

以取代的芳基酮为原料, 合成了一系列6,6-取代芳基富烯, 这些富烯都经过了核磁共振、元素分析、质谱和红外光谱的鉴定. 芳基酮上的取代基决定了合成中所用碱的类型. 对于含吸电子取代的酮, 采用乙醇钠作为碱可以达到很高的产率, 而对于含烷基等推电子取代的酮, 用环戊二烯基钠直接反应是一种比较好的合成方法.     

二茂镁的原位合成及其与羰基化合物的反应

研究了通过萘锂还原法制得的活性镁与环戊二烯原位合成环戊二烯基镁(Cp~2Mg)的方法。Cp~2Mg的存在是由它与醛酮反应生成富烯得到证实。此法产率高, 方法简单, 条件温和。     

二茂铁基β-二酮及其Cu(Ⅱ)、Ni(Ⅱ)配合物的燃速催化性质

合成了含有苯基的二茂铁β-二酮,并对其结构进行了表征.在核磁共振氢谱中,苯环上含有拉电子的硝基时,β-二酮烯醇式含量几乎是100%,而含有给电子的甲氧基时,其烯醇异构体含量下降到84%.当将其与Cu(II)或Ni(II)配位后,在紫外吸收光谱中,300 nm以下归属于Fe(d)-π*和芳基π-π*的跃迁向长波方向移动5~17 nm.热重-差示扫描量热法(TG-DSC)实验表明,添加二茂铁基β-二酮或它们的Cu(II)或Ni(II)配合物于高氯酸铵(AP)中,不仅在一定程度上抑制了AP高温热降解阶段的升华,而且可使AP的热降解温度提前,以Cu(II)配合物提前得更为显著,含有甲氧基的Cu(II)配合物可使AP的热降解温度提前87℃.因此相对于二茂铁β-二酮配体及Ni(II)配合物,Cu(II)配合物是更好的燃速催化剂.     

聚氯乙烯的热可逆共价交联

利用环戊二烯 (CPD)在常温下自动二聚形成双环戊二烯 (DCPD)、在高温下DCPD又可解聚成CDD的热可逆Diels Alder反应 ,合成了DCPD二羧酸衍生物 ,并将其引作聚氯乙烯 (PVC)的共价交联 ,研究了交联剂种类和用量对交联程度、力学性能和流动特性的影响及交联产物的热可逆转化行为 ,制得了力学性能和耐热性均有所提高的热可逆共价交联PVC     

含氮杂茂配体的类茂配合物NpCpTiCl_2催化乙烯聚合研究

茂金属催化烯烃聚合时不仅须大量甲基铝氧烷(MAO)作助催化剂,而且其稳定性较差,结构修饰困难,这都一定程度上限制了茂金属催化剂的发展.近几年来,将非环戊二烯类配体与IVB 族金属作用形成的配合物应用于催化烯烃聚合的研究大量出现[1],其中非环戊二烯配体有脒化物[2,3]、酰胺基[4,5]、NFDA3唑啉[6]、卟啉[7 ]、烷氧基[8]、芳氧基[9～11]、和β-二酮[12,13]、8-羟基喹啉[14～16]等.这些非茂配合物均可催化乙烯或丙烯聚合,但活性都较低.我们曾制备了含配位原子为氧或氮的非环戊二烯基配体的半茂配合物,即茂金属中一个环戊二烯基配体被非环戊二烯基配体取代,使金属中心与一个茂和一个非茂配体配位而形成的桥连或非桥连型的配合物[17,18].这类配合物不仅稳定性好,而且消耗的助催化剂量较少,活性高,对所得聚合物的结构有一定的控制作用.桥连型半茂配合物以“限制几何构型”催化剂为代表[16,19～20 ],非桥连型半茂配合物的报道较少,如CpTi(OiPr)Me2和CpTi(OAr)X2 [21 ,22].我们选择氮杂茂类配体为非环戊二烯阴离子配体,氮杂茂环以一价阴离子的形式与金属中心钛配位,与另一个环戊二烯阴离子形成类茂型配合物.这种类茂配合物易于制备, 稳定性好,而且消耗的助催化剂量较小.     

PMBP缩磺胺席夫碱及其铜配合物的合成与抑菌活性

4-酰基吡唑啉酮类化合物是一类重要的有机配体.其所具有的酮式和烯醇式异构体并存且含有多个配位原子的特性使得该类化合物在与金属离子配位时存在多种配位方式,从而形成单核、同双核、异双核和多核等金属配合物[1-5].     

Polysiloxane zwitterionomers and related model compounds. I. Synthesis

Polymers containing zwitterions were prepared by reacting γ-propanesultone with polydimethylsiloxane-co-(4,7-diazaheptylmethylsiloxane), which generated substituted di(ammonium-3-propane-sulfonate) groups pendant from the siloxane chain. Their concentration in the polymers varied from 0.5 to 10 mole %. Two model compounds were also prepared in order to (1) characterize the reaction leading to the formation of these zwitterions and (2) characterize the ionic forces in solutions (tetrahydrofuran and benzene were used as solvents). The degree of aggregation of these model compounds was higher in tetrahydrofuran and increased in both solutions with the concentration. No rearrangements of siloxane bonds were observed in the presence of these zwitterions or γ-propanesultone.     

Dual column capillary gas chromatographic system for the in situ analysis of volatile organic compounds on a cometary nucleus

Two Wall Coated Open Tubular capillary columns, coated with poly(cyanopropylphenyl-dimethyl)siloxane and poly(diphenyl-dimethyl)siloxane stationary phases, have been selected for use in the COmetary SAmpling and Composition space experiment for the separation and identification of the wide range of volatile organic compounds which could be present in cometary nuclei. This article presents the main characteristics of the tandem column system for the analysis of solutes of cometary interest within the constraints of space instrumental operating conditions. The high efficiency of the columns is demonstrated and the influence of the operating conditions on their separation properties are investigated. The studied columns exhibit complementary retention pattern: their use in a dual column system makes it possible to achieve the separation and the identification of the compounds of interest. Finally, the good analytical behavior of the columns when analyzing samples which include large amounts of water, the main presumed volatile in comets, is demonstrated. The presented results thus show the suitability of the selected tandem columns system for the desired analyses, and their performance on adaptation to in-situ cometary chemical investigation.     

Alkylpyrrolidiniumtrialkoxysilyl iodides as organic iodide sources for dye-sensitised solar cells

Two new alkylpyrrolidiniumtriethoxysilyl iodides have been developed as iodide sources for DSSCs; the compound with an undecyl spacer between the siloxane and the pyrrolidinium moieties furnished higher open circuit voltages than the propyl analogue and higher efficiencies at low light intensity.     

Modifications of poly(methyl-3-propylthiol)siloxane to give stationary phases for open tubular supercritical fluid chromatography

Summary Poly(methyl-3-propylthiol)siloxane has been evaluated for use as stationary phase in open tubular columns for gas and supercritical fluid chromatography. Immobilization of the stationary phase was achieved by crosslinking with 2,4,6-trichloro-1,3,5-triazine. The poly(methyl-3-propylthiol)siloxane stationary phase film was in situ oxidized to the disulphide and sulphonic acid forms and both have been evaluated for use in supercritical fluid chromatography. Good selectivity towards polar polycyclic aromatic compounds has been shown. All the modified forms of the stationary phase were loaded with silver ions and were evaluated with regard to ligand exchange chromatography using supercritical fluid carbon dioxide as a mobile phase. The utility of the stationary phase, having sulphonic acid groups loaded with silver ions, has been demonstrated by separation of fatty acid methyl esters according to their unsaturation.Dedicated to Professor Leslie S. Ettre on the occasion of his 70th birthday.     

Evidence for chiral organometallic intermerdiates in stereospecific phosphine exchange reactions

Trivalent phosphorus ligand groups have been bonded to a wide range of organic polymers, including polyvinyl chloride, polystyrene, polybutadiene and polyvinyl alcohol. The ligand-polymers complex with a variety of transition metal compounds, and the complexes obtained have been shown to catalyse hydrocarbon reactions such as the hydrogenation of 1-hexene and cyclohexene, the hydroformylation of 1-hexene and the cyclodimerisation of butadiene to 4-vinylcyclohexene and 1,5-cyclooctadiene. Macroreticular high surface area cross-linked polystyrene is the most satisfactory organic polymer support.Rhodium complexes of acetylacetone ligand-polymers have also been prepared.     

Hybrid Porous Materials with High Surface Area Derived from Bromophenylethenyl‐Functionalized Cubic Siloxane‐Based Building Units

Sonogashira cross‐coupling of bromophenylethenyl‐terminated cubic, double four‐ring, siloxane cages with di‐/triethynyl compounds results in microporous poly(ethynylene aryleneethenylene silsesquioxane) networks, simply termed as polyorganosiloxane networks (PSNs). In comparison with porous organic polymers reported previously, these PSNs show relatively high surface area and comparable thermal stability. Their apparent BET specific surface areas vary in the range of 850–1040 m² g^?1 depending on the length and the connectable sites of the ethynyl compounds. Analyses of pore size distribution revealed bimodal micropores with relatively narrow distribution. The degree of cross‐linking affects the degree of cleavage of the siloxane bonds, and this suggests that partial cleavage of the siloxane cages is mainly a result of cage distortion. Hydrogen adsorption was performed to evaluate potential of the PSNs as hydrogen storage media. Uptakes of up to 1.19 wt % at 77 K and 760 Torr and initial isosteric heats of adsorption as high as 8.0 kJ mol^?1 were observed. These materials have been obtained by a combination of structural, synthetic organic, and materials chemistry, which can exploited to synthesize porous hybrid materials with specifically designed structures and functions.     

New poly(amide-imide) siloxane copolymers by polycondensation

Some new poly(amide-imide) siloxane copolymers have been synthesized by solution polycondensation of some aromatic diamines with siloxanic diacids having preformed imide rings. Two polycondensation techniques were used: polycondensation of aromatic diamines with diacid chlorides and direct polycondensation of aromatic diamines with diacids in the presence of organic phosphites, following the Yamazaki-Higashi phosphorylation technique. In all cases the reactions were carried out using equimolecular amounts of the two monomers, in polar aprotic solvents and inert atmosphere.The obtained compounds were characterized by elemental C, H and Si analysis, solubility tests, IR and ¹H-NMR spectrometry. Thermogravimetric curves were also recorded. All data agree with the proposed structures.     

Structure–property co‐relationship of fluorinated poly(imide‐siloxane)s

Eight poly(imide‐siloxane)s co‐polymers have been prepared by one pot solution imidization method. The polymers are synthesized by the reaction of bisphenol‐A‐dianhydride (BPADA) with fluorinated diamine 4,4′‐bis(3″‐trifluoromethyl‐p‐aminobiphenyl ether) biphenyl, and aminopropyl‐terminated polydimethylsiloxane (APPS). The polymers are synthesized by varying the siloxane loading to 5, 10, 15, 20, 25, 30, 35, and 40 wt%, respectively. Thermal, mechanical, rheological, and dielectric properties of these polymers have been evaluated with respect to siloxane loading. The polymers showed glass transition temperature of 107–203°C and tensile strength at break of 24–75 MPa depending on siloxane loading. The elongation break of the polymers ranges from 24 to 144% depending on siloxane loading. The amounts of char residue in the polymers have been correlated with incorporated siloxane in the polymer by NMR techniques. The polymers showed very low water absorption and dielectric constant as low as 2.43 when the siloxane loading is 40 wt%. Copyright © 2008 John Wiley & Sons, Ltd.     

Preliminary communication Bi-mesogenic organosiloxane liquid crystal materials exhibiting antiferroelectric phases

The first antiferroelectric low molar mass organosiloxane liquid crystal materials are presented. The molecules are bi-mesogens consisting of two chiral mesogenic units attached, via methylene spacers, symmetrically to a siloxane group. Three series of compounds with different laterally substituted halogens on the phenyl ring nearest to the chiral centre have been studied. For siloxane groups containing three silicon atoms all of the materials exhibit antiferroelectric phases over a 60 C temperature range. The tilt angle in the SmC* A is, within experimental uncertainties, independent of temperature and close to 45 degrees for the three series with a spontaneous polarization greater than 110nC cm -2.     

Analysis of siloxane pyrolysis products by cryo-GC/FT-IR and GC/MS

On line measurements of infrared and mass spectra of siloxane pyrolysis products separated by gas chromatography are described. The FT-IR absorbance spectra have been recorded from the eluates trapped as small spots on a moving window held at 77 K. Three of the main compounds separated were selected for FT-IR identification performed by comparing the spectra with GC/MS data and by spectral searching using a library of compounds measured under the same conditions.Dedicated to our most honourable teacher Professor Dr. H. Kriegsmann on the occasion of his 70th birthday