Evaluation of catalytic efficiency of a triple-site phase transfer catalyst and the kinetics of dichlorocarbene addition to 5-vinyl-2-norbornene

A new triple-site phase transfer catalyst viz., 1,3,5-tris(ethylmethyleneammonium bromide)-2,4,6-trimethyl benzene (TEMABTB) was prepared by the quaternization of 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene using triethylamine and its catalytic efficiency was ascertained by following the kinetics of dichlorocarbene addition of 5-vinyl-2-norbornene. Comparative catalytic activity of various onium salts (single-, di- and tri-site) have been investigated in detail. Based on the kinetic results obtained, a plausible mechanism has been proposed.     

Investigations on surface modified dendrimers: enzymatic hydrolysis and uptake into MCF-7 breast cancer cells

A series of G(0) and G(1) generation 1,3,5-tris(3-aminopropyl)benzene dendrimers surface modified with the amino acids phenylalanine (Phe), methionine (Met), aspartic acid (Asp), and diaminopropionic acid (Dap) was investigated with regard to their stability against enzymatic hydrolysis with the model enzymes papain, chymotrypsin, trypsin, and pepsin. Additionally, the cytosol of MCF-7 cells was used to get an insight into the possible degradation in intracellular medium. The cytosol, chymotrypsin, and papain had similar activities on the tested dendrimers and efficiently cleaved methionine and phenylalanine from the surface of the dendrimers. The cellular uptake of the dendrimers into the MCF-7 cells depended on the surface modification (Phe>Met unmodified>Dap=Asp) and the generations (G(0)>G(1)).     

Influence of vinyl-terminated hyperbranched polyester on performance of films obtained by UV-initiated thiol–ene click reaction of A<Subscript>2</Subscript> + B<Subscript>3</Subscript> system

UV curing technology has become an efficient method to fabricate films with desirable properties, although it is susceptible to oxygen inhibition, resulting in low conversion of double bonds and poor mechanical performance. Thiol–ene click reaction can overcome the shortcomings of common UV curing techniques. In this paper, the vinyl-terminated hyperbranched polyester (VTDP) was incorporated into the curing system of di-ene (A₂) and trithiol (B₃). Trithiols, including 1,3,5-tris(2-hydroxyethyl)isocyanurate tris(3-mercaptopropionate) (THMP) and trimethylolpropane tris(3-mercaptopropionate) (TMMP), were synthesized by an esterification between 3-mercaptopropionic acid and 1,3,5-tris(2-hydroxyethyl) isocyanurate, and tri(hydroxymethyl)propane, respectively. The UV-initiated thiol–ene click reaction between 1,4-butanediol diacrylate (BDDA) and trithiols (TMMP and THMP) was researched by adjusting different VTDP content. FTIR spectral analysis showed that the thiol–ene reactions proceeded smoothly and the conversion degree of acrylic groups was higher than that of thiol groups. The pencil hardness and abrasion resistance of the cured film increased first and then decreased with the increase in VTDP content, but both their flexibility and adhesion had little change. Their glass transition temperatures increased slightly with the increase in VTDP content. THMP has better positive effect than TMMP on the pencil hardness, abrasion resistance and thermal performance of the cured film.     

Antioxidants and stabilizers. L. Transformation of the 1,3,5-tris(4-hydroxy-3,5-di-tert-butylbenzyl)cyanuric acid into alkylperoxycyclohexadienones,their properties and effects on the oxidation of tetralin and polypropylene

The transformation of 1,3,5-tris(4-hydroxy-3,5-di-tert-butylbenzyl)cyanuric acid (I), designed as an antioxidant for polyolefins, during its reaction with tert-butylperoxyls was studied. In tert-butyl alcohol two oxidation products, II and III, are formed, while in benzene the reaction proceeds faster with formation of cyclohexadienone III. The structures of the oxidation products were confirmed, their thermal properties were measured (by DTA) and the effect on the oxidation of tetralin and isotactic polypropylene was determined. The oxidative transformation makes trisphenol I lose its antioxidative property. The different behaviour of trisphenol I and another important phenolic antioxidant, namely, 1,3,5-trimethyl-2,4,6-tris(4-hydroxy-3,5-di-tert-butylbenzyl)benzene (IV) under the conditions of inhibited oxidation of polyolefins is discussed.     

不同胺取代三嗪衍生物对高密度聚乙烯阻燃性能的影响

以三聚氯氰、甲胺和二甲胺水溶液为原料,合成了2,4,6-三甲胺基-1,3,5-均三嗪(TMM)和2,4,6-三二甲胺基-1,3,5-均三嗪(HMM),并用FT-IR和DSC对其进行了表征。研究了用多聚磷酸胺(APP)和季戊四醇(PER)作为酸源和炭源,分别用三聚氰胺(MEL)、TMM和HMM作为气源的膨胀型阻燃剂对高密度聚乙烯(HDPE)力学性能和阻燃性能的影响。结果表明:含TMM的HDPE复合材料的阻燃性能和力学性能都优于含MEL或HMM的HDPE复合材料。     

新型含三嗪结构氧杂膦菲阻燃剂的合成

以三聚氯氰、对羟基苯甲醛和9,10-二氢-9-氧杂-10-膦菲-10-氧化物(DOPO)为主要原料,经两步反应合成了一种新型含三嗪结构氧杂膦菲阻燃剂PN-FR。第一步反应以三聚氯氰、对羟基苯甲醛为原料,二氯甲烷和水为混合溶剂,相转移催化剂作用下回流反应2 h,得2,4,6-三(4-醛基苯氧基)-1,3,5-三嗪(ZJT),收率98.8%;第二步在n(DOPO)∶n(ZJT)∶n(催化剂)=3.2∶1∶0.8,66℃回流反应3 h条件下得目标产物PN-FR,收率95.8%。用FTIR、EA、1HNMR、LC/MS、TG和DSC对中间体和产物作了结构表征和热性能分析。将该阻燃剂初步应用于环氧树脂绝缘层压板的阻燃,当阻燃剂质量分数为15%时,绝缘层压板氧指数达到36.2,通过UL-94 V-0级测试。该文研究工作的新颖性,已为四川省科学技术信息研究所2006年10月26日出具的第A0601512号《科技查新报告》所证实。     

苯氧基二氯均三嗪改性纤维素的合成与水解

以三聚氯氰(TCT)、苯酚为原料,合成2,4-二氯-6-苯氧基-1,3,5-三嗪衍生物(PHCT);通过红外光谱和质谱表征其结构。用PHCT对纤维进行修饰,并将修饰后的微晶纤维素在8%(wt)H2SO4中、130℃下水解5 h,研究PHCT用量对纤维素水解性能和结晶结构的影响;实验结果表明,经PHCT改性的纤维素水解后的还原糖得率提高了,当PHCT相对摩尔含量(以葡萄糖环计)为16.67%时,纤维素水解成还原糖得率最大为23.54%;通过分析广角X射线衍射图发现,PHCT改性使微晶纤维素的结晶结构发生变化,无定形区增加,结晶指数下降,晶粒尺寸减小。     

Electrochemical and spectral properties of meta-linked 1,3,5-tris(aryl)benzenes and 2,4,6-tris(aryl)-1-phenoles, and their polymers

We present electrochemical and spectral properties of symmetric monomers 1,3,5-tris(aryl)benzenes and 2,4,6-tris(aryl)-1-phenols and their polymers. These compounds contain thienyl, furyl or EDOT moieties attached to central benzene or phenol ring at the meta-position, synthesized by a Stille cross-coupling procedure. All monomers are electroactive and undergo electropolymerization creating thin films on an electrode surface. Polymers with meta-linkages were obtained by electrochemical oxidation. Detailed cyclic voltammetry and in situ UV-vis spectroelectrochemistry show that polymers with hydroxy groups exhibit higher conductivity and better stability than with benzene core. Interesting and different behavior occurs for 2,4,6-tris(2-thienyl)-1-phenol, for which the characteristic, sharp, redox peak is observed.     

1,3,5-三(3,3,4,4,5,5,6,6,6-九氟己基)-1,3,5-三甲基环三硅氧烷的合成

标题化合物是一种合成共氟硅材料的重要单体。以全氟丁基乙烯和甲基二氯硅烷为原料,经硅氢加成反应合成了氟烃基甲基二氯硅烷,再经水解反应制得其水解产物,最后在CsOH催化下,经裂解反应制备了目标化合物。产物经~1HNMR、~(13)CNMR、~(19)FNMR及IR确认结构。     

1,3,5-三（4-二苯胺基苯乙炔基）-2,4,6-三（4-腈基苯乙炔基）苯的合成及表征

利用微波反应合成了一种新型二阶非线性光学化合物1,3,5-三（4-二苯胺基苯乙炔基）-2,4,6-三（4-腈基苯乙炔基）苯,通过红外、核磁共振、元素分析等手段对产物结构进行了表征。紫外可见光的吸收光谱的研究表明,该产物有希望成为1064 nm激光的倍频材料。     

2-噁唑啉化合物的合成及其在聚合物中的应用

综述了近年来2-噁唑啉化合物在合成领域的研究进展,主要介绍了β-氨基醇与羧酸或羧酸酯反应,酰胺环化反应,以腈类化合物为原料反应等合成方法。总结了2-噁唑啉化合物在聚合物改性方面的应用进展,并预测了2-噁唑啉化合物的合成与应用发展趋势。     

Recombination zone study of phosphorescent organic light-emitting diodes with triplet mixed host emitting structure

Recombination zone of green phosphorescent organic light-emitting diodes (PHOLEDs) with triplet mixed host was studied using red sensing layer. Recombination zone of triplet mixed host device with 4,4′,4″-tris(N-carbazolyl)triphenylamine and 1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene as hosts was rather dispersed compared with that of single host device with recombination zone near charge transport layer. The recombination zone was shifted to hole transport side at high driving voltage.     

Synthesis of the Ladder Polymers by the Reaction of Catalytic Dehydrocondensation

Abstract

The heterofunctional condensation of cis-1,3.5,7-tetrahydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane with dimethylchlorosilane has been studied.

It was established that when the reaction proceeds under mild conditions tetraphenylcyclotetrasiloxane incompletely substituted with dimethylsiloxy groups is obtained, i.e., 1,3,5-tris(dimethylsiloxy)-7-hydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane, while under certain conditions 1,3,5,7-tetrakis(dimethylsiloxy)-1,3,5,7-tetraphenylcyclotetrasiloxane is formed.

The catalytic dehydrocondensation of 1,3,5-tris(dimethylsiloxy)-7-hydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane both in a dilute and concentrated solutions in the presence of platinochlorohydric acid as a catalyst has been studied. It was shown that the reaction proceeds both by the mechanism of intramolecular cyclization with formation of a bicyclic compound and intermolecularly with formation of a tricyclic compound.

The catalytic dehydrocondensation of 1,3,5,7-tetrakis-(hydriddimethylsiloxy)-1,3,5,7-tetraphenylcyclotetrasiloxane with cis-1,3,5,7-tetrahydroxy-1,3,5,7-tetraphenylcyclotetrasiloxane and with oligotetrols (m = 5, 10) was also studied. The reaction order, activation energies and dehydrocondensation rate constants were found.

It was established that with an increase in the length (m) of the oligotetrols the degree of catalytic dehydrocondensation is reduced. It was shown that if the platinochlorohydric acid catalyst is replaced by anhydrous powdered caustic potassium a different configuration of the cyclotetrasiloxane skeleton is realized in polymers.     

Structure–property–processing relationships in chemically modified LDPE and LDPE/LLDPE blend

The properties of low-density polyethylene (LDPE) and its blend with linear low-density polyethylene LDPE : LLDPE (75 : 25) modified with varying concentrations of dicumyl peroxide (DCP) were compared. Chemical modification was carried out in a Brabender plasticorder under set conditions of temperature, rotor speed, and time. The results are reported in terms of the type of polyethylene used, concentration of DCP, mixing torque, temperature and time on the processing, and mechanical and physical properties of the modified samples. Interpretation of the results is given in terms of gel contents which relate to the three-dimensional network structure of polyethylene. The modified blend forms a denser network structure and, hence, better product properties relative to that of modified LDPE, indicating the influence of LLDPE in increasing the rate and extent of crosslinking on blending with LDPE. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:789–797, 1998     

Organization of poly(2-ethyl-2-oxazoline)-block-poly(2-phenyl-2-oxazoline) copolymers in water solution

Diblock copolymers were prepared from 2-ethyl-2-oxazoline and 2-phenyl-2-oxazoline via living cationic polymerization using sequential addition of the monomers. Copolymer assemblies in aqueous solutions and on surface were studied with respect to changes in the hydrophilic-hydrophobic balance induced by increasing the length of the hydrophobic poly(2-phenyl-2-oxazoline) segment while the hydrophilic poly(2-ethyl-2-oxazoline) chain was kept constant with an average of 60 monomer units. The copolymer with a short segment of four 2-phenyl-2-oxazoline units assembled into highly hydrated aggregates that decreased twice in size after drying. Their structure was destroyed and network morphologies were formed upon spin-coating. The increase of the length of the hydrophobic segment resulted in aggregates that dissociated to micelle-sized particles when subjected to mechanical shear by spin-coating or filtering. These observations imply that the aggregates are multi-core structures originating from the assembly of primarily formed micelles. The copolymer self-assembly was evidenced by a combination of techniques: DLS, SLS, AFM and SEM.     

Mechanism of increasing the reducing sugar yield in cellulose hydrolysis via modification with 2,4-dianilino-6-chloro-s-triazine

Cellulose, one of the most abundant and useful natural resources from products of forests, has become increasingly important because of its conversion to bio-ethanol. Yet, the low yield of the conversion is the key problem that should be solved. Microcrystalline cellulose was chemically modified with 2,4-dianilino-6-chloro-1,3,5-triazine to increase the yield of hydrolysis of cellulose for high glucose generation. The modifier, 2,4-dianilino-6-chloro-1,3,5-triazine, was synthesized from 2,4,6-trichlorine-1,3,5-triazine and aniline, and the chemical structure of the modifier was determined by Fourier transform-infrared, nuclear magnetic resonance and mass spectrometry techniques. The structure of the modified microcrystalline cellulose was characterized by Fourier transform-infrared spectrometry and wide-angle X-ray diffraction techniques. The hydrolysis of the modified microcrystalline cellulose had been studied and the yield of the reducing sugar reached the highest when the relative molar percentage of 2,4-dianilino-6-chloro-1,3,5-triazine to the cellulose (based on the remained glucose unit) was about 30 %. The change of the crystalline structure of cellulose by chemical modification, which was suggested by wide-angle X-ray diffraction spectra, was propitious to the hydrolysis of cellulose. Furthermore, the yield of hydrolysis varied with the loading of the modifier which was due to the change of the crystalline structure of the modified cellulose. It might be a probable mechanism of yield improvement via modification that was verified by the calculated result of crystalline index and crystallite size.     

基于Aldol缩合反应的碳碳双键共价有机框架材料的设计合成

具有C₃对称性的三甲基三嗪（TMT）分别与2,4,6-三(4-醛基苯基)-1,3,5-三嗪（TFPT）、均三苯甲醛（TFB）和四氟对苯二甲醛（TFBA）在酸或者碱催化条件下发生Aldol缩合反应,成功构建出3种新型的碳碳双键桥联的共价有机框架材料（TMT-TFPT-COF、TMT-TFB-COF、TMT-TFBA-COF）。本研究通过Material Studio、ZEO⁺⁺等软件对材料进行结构的精确解析,并结合粉末X射线衍射（PXRD）、傅里叶红外光谱（FTIR）等表征手段确定了材料的结构、连接方式及其荧光特性。结果表明,这3种较高结晶度的新型共价有机框架材料均为二维层层堆积结构,其中碱催化条件下合成的TMT-TFPT-COF、TMT-TFB-COF材料呈现出良好的荧光性质,此类荧光COFs材料在光催化、化学传感器等方面具有很好的应用潜力。     

Shear rheology and melt compounding of compatibilized‐polypropylene nanocomposites: Effect of compatibilizer molecular weight

Direct melt compounding was used to prepare nanocomposites of organophilic montmorillonite (o‐mmt) clay dispersed in maleated polypropylenes (PPgMA) as well as nanocomposites of organoclay and polypropylene (PP) modified with various grades of PPgMA compatibilizers. The thermal effect on the rheology and melt compounding was first investigated with a plasticorder. The shear viscosities and the melt flow indices (MFI) of the PPgMA compatibilizers were sensitive to the blending temperature, which had to be varied with the compatibilizer grade to achieve desirable level of torque for extensive exfoliation of organoclay in the plasticorder. However, for low molecular weight oligomer, the clay dispersion was poor because of low shear viscosity and thermal instability. Next, the PPgMA‐modified PP/organoclay nanocomposites were prepared on a corotating twin‐screw extruder. The nanoscale dimensions of the dispersed clay platelets led to significantly increased linear viscoelastic properties, which were qualitatively correlated with the state of exfoliation in the nanocomposites. The relative viscosity (relative to the silicate‐free matrix) curves revealed a systematic trend with the extent of clay exfoliation. Furthermore, the degree of clay dispersion was found to increase with the loading of compatibilizers; however, high loading of compatibilizer compromised the final moduli of the nanocomposites. POLYM. ENG. SCI. 46:289–302, 2006. © 2006 Society of Plastics Engineers     

双端乙烯基氟硅油的研制

以1,3,5-三甲基-1,3,5-三(3,3,3-三氟丙基)环三硅氧烷为原料、四甲基二乙烯基二硅氧烷为封端剂、硫酸为催化剂制得双端乙烯基氟硅油,研究了反应时间、催化剂用量、反应温度对产物黏度和挥发分质量分数的影响;采用红外光谱和核磁共振波谱表征了产物结构.结果表明,产物为双端乙烯基氟硅油.较佳的制备条件为反应时间1 h...     

氟硅防指纹透明涂层的构建及性能

以三氟丙基甲基环三硅氧烷(D3F)、四甲基四乙烯基环四硅氧烷(D4vi)、六甲基二硅氧烷(MM)和三甲氧基氢硅烷(TMS)为原料,经开环聚合,硅氢加成反应制得了烷氧基改性含氟聚硅氧烷(FVT);FVT与正硅酸乙酯(TEOS)、全氟辛基三甲氧基硅烷(POTS)进行分步水解缩聚,得到了一种纳米改性氟硅树脂(FVT-SiO_2),并以FVT-SiO_2为成膜物质,制备了防指纹透明涂层。用FTIR、SEM、XPS对产物的结构、形貌及性能进行了测试与表征,讨论了分步水解反应条件对涂层接触角的影响。结果表明:待FVT与TEOS先反应2h,再加入POTS进行分步反应,可得到平均粒径约150 nm,分散均匀的球状FVT-SiO_2。且当w(FVT-SiO_2)=2%、浸涂层数为3层时,得到的涂层透明性良好、附着力强且疏水疏油性最佳,其水和油的接触角分别达到138.5°、109°。