End‐functionalization of syndiotactic polystyrene by vinylsilane inducing selective chain transfer reactions

Structurally well‐defined end‐functionalized syndiotactic polystyrene (sPS) can be prepared by conducting a simultaneous selective chain transfer reaction during the syndiospecific polymerization of styrene in the presence of vinylsilanes. The production of vinylsilane end‐capped sPS involves a unique selective chain transfer pathway via the incorporation of a terminal vinylsilane unit at the polymer chain end by 2,1‐insertion. This unusual insertion pattern situates the bulky silyl functional group at a closer β‐position from the active catalyst center, thus deactivating the propagating chain by a steric jam between the vinylsilane end group and the active catalyst. Subsequently, chain releasing by hydrogen addition (in the presence of H₂) or by β‐elimination (in the absence of H₂) can take place, which leads to the production of end‐functionalized sPS with precise controls of stereoregularity and of the location of functionality. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1690–1698, 2010     

Synthesis and characterization of cationic latex particles bearing sulfhydryl groups and their use in the immobilization of Fab antibody fragments (1)

Emulsion copolymerization of styrene and a cationic monomer vinylbenzyl-isothiouronium chloride (VBIC) with initiation by 2,2 azobis(2-amidinopropane)-dihydrochloride (V-50) gave monodisperse latex particles. After post-stabilization with cationic or non-ionic surfactants, the colloids were diluted in basic buffers with concomitant deprotection of the sulfhydryl groups. Therefore, coupling reactions on the latex beads were possible. Coupling conditions were determined with Ellman's reagent.¹⁴C iodoacetamide and anti C-reactive protein antibody Fab fragments were immobilized and finally, the immunological activity of the sensitized latex was assessed.     

Amberlite XAD-2键合双硫腙螯合树脂现场预富集测定水中痕量铅

以Amberlite XAD-2树脂与双硫腙通过N N基键合的形式合成了一种新型螯合树脂(XAD-H2DZ),采用IR和TGA技术对其特性进行了表征,并将其应用于微柱现场在线采样(MFS)新技术中,实现了环境水样中痕量铅的在线原位预富集和实验室中流动注射-火焰原子吸收(FI-FAAS)系统的联机测定。当采样体积为10和50 mL时,其富集因子分别为78和384倍;检出限(3σ)分别为0.32和0.079μg/L;相对标准偏差(n=7)分别为2.0%和1.9%。对环境水样标准物质(GBW 08608)、海水中微量元素标准物质(GBW(E)080040)和实际样品(大连老虎滩区域海水以及南湖水)中铅进行分析,均获得了满意的结果。     

功能化多壁碳纳米管填充的凝胶电解质在染料敏化太阳能电池的应用

纯聚偏氟乙烯-六氟丙烯共聚物(PVDF-HFP)基凝胶电解质常常受制于低离子电导率,阻碍了其在染料敏化太阳电池(dye-sensitized solar cells,DSSCs)中的应用。 而利用纳米填充可提高凝胶电解质离子电导率及凝胶电解质DSSCs的性能。 本文使用功能化的多壁碳纳米管(f-MWCNT)作为PVDF-HFP凝胶电解质的纳米填充物,通过改变f-MWCNT的质量分数来研究其对电解质的离子电导率和离子扩散的影响,进而研究其对DSSCs的转化效率和长期稳定性的增强作用。 研究发现:质量分数0.5%的f-MWCNT明显提高了PVDF-HFP凝胶电解质的离子电导率和离子扩散系数。 并且,该凝胶电解质基DSSCs的光转换效率可达5.28%,相比于未填充的PVDF-HFP凝胶电解质基DSSCs(4.01%),其效率提高了31.7%。 42 d后,该电池依然可以保持最初转化效率的86.5%。 实验结果证实了f-MWCNT在纳米填充方面的巨大潜能,为采用纳米填充物提高凝胶电解质DSSCs的性能提供参考。     

Functional tuning of nucleic acids by chemical modifications: tailored oligonucleotides as drugs,devices, and diagnostics

Chemical modifications of nucleic acids present vast opportunities for extending the functions and properties of these biomolecules. In general, efforts invested in this direction pertain to the introduction of reactive functional groups for further derivatizations of oligonucleotides with numerous reporter groups and for equipping nucleic acids with catalytic chemical moieties. This review deals with representative chemical modifications in the nucleobases, sugars, and the phosphate ester backbone and their application from novel catalytic RNA selection to nucleic acid-based biosensors.     

Curing characteristics of carboxyl functionalized glucose resin and epoxy resin

The curing characteristics of carboxylic functionalized glucose resin (glucose maleic acid ester vinyl resin: GMAEV) and epoxy resin have been studied using DSC and FTIR methods. Exothermic reactions attributed to esterification and etherification reactions of the hydroxyl and carboxyl functionalities of GMAEV with the epoxy groups were identified. Exothermic reactions showed very different patterns according to the degree of carboxyl group substituent of GMAEV. The results showed that esterification reaction occurs in the early stage of cure and then etherification followed after completion of the esterification. A cured matrix containing epoxy resin and 50 wt.% of GMAEV was prepared and characterized. The cured matrix showed thermal stability up to 300 °C. The average glass transition temperature and storage modulus of the matrix were as high as 95 °C and 2700 MPa, respectively. The cured matrix of epoxy resin and GMAEV with higher degree of carboxyl group was found to have a lower density due to the formation of bulky groups in the crosslinks.     

硅烷功能化碳点荧光探针检测槲皮素

以柠檬酸为碳源,硅烷偶联剂为表面包覆剂,一步水热法合成了高效发光硅烷功能化碳点。所得碳点在360 nm激发后在450 nm处有强荧光发射峰,荧光量子产率最高可达69.2%。基于槲皮素对该碳点荧光的猝灭作用,建立了一种以硅烷碳点为荧光探针的简便、灵敏检测槲皮素的分析方法。考察了作用时间、pH值、碳点用量对槲皮素检测的影响,并探讨了荧光猝灭机制。在优化实验条件下,该方法对槲皮素的检测线性范围为1.0～40.0μmol/L,相关系数(r)为0.996 7,检出限为3.8 nmol/L。该方法应用于实际样品中槲皮素的测定,结果满意。     

Crystal structure of 25,27-bis[(2-cyanophenyl)methoxy] calix[4]arene

The crystal structure of 25,27-bis[(2-cyanophenyl)methoxy] calix[4]arene (C₄₄H₃₄N₂O₄) was determined by X-ray crystallographic analysis. It possesses space group R , with a = b = 35.993(8) Å, c = 13.842(3) Å, = = 90°, = 120°, and D _calc = 1.260 mg/cm³ for Z = 18. Crystal data indicate that Compound 1 exists in a pinched-cone conformation with intramolecular hydrogen bonds.     

End‐functionalization of polystyrene by malto‐oligosaccharide generating aggregation‐tunable polymeric reverse micelle

This article describes that glucose, maltose, maltotriose, maltotetraose, maltopentaose, and maltohexaose ( a , b , c , d , e , and f , respectively) were introduced into the initiating chain‐end of polystyrene (PSt) through the 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO)‐mediated radical polymerization. A series of glycoconjuaged TEMPO‐adducts, 1a–f , was synthesized and used as the initiators for the polymerization of styrene (St) for 6 h at 120 °C to afford the end‐functionalized PSt's with the acetyl saccharides, 2a–f , in the yields of 37–43%. For 2a–f obtained by the polymerizations using the [St]/[ 1 ] of 125, 250, and 500, the number‐average molecular weights determined by size exclusion chromatography (SEC), M_n,SEC's, were 4800–6300, 8800–10,600, and 18,400–25,200, respectively, which fairly agreed with the predicted values. The end‐functionalized PSt's with saccharides, 3a–f , which were obtained from the deacetylation of 2a–f using sodium methoxide in dry THF, formed the polymeric reverse micelles consisting of a saccharide‐core and a PSt‐shell in chloroform and toluene. The static laser light scattering (SLS) measurements provided the average molar mass of the aggregates in toluene, M_w,SLS's, which ranged from 7.50 × 10⁴ to 1.77 × 10⁵ for 3a , from 1.90 × 10⁵ to 4.93 × 10⁵ for 3b , from 4.41 × 10⁵ to 7.21 × 10⁵ for 3c , from 5.85 × 10⁵ to 8.51 × 10⁵ for 3d , from 7.55 × 10⁵ to 8.53 × 10⁵ for 3e , and from 8.54 × 10⁵ to 9.26 × 10⁵ for 3f . The aggregation numbers, N_agg's, which were calculated from the M_w,SLS's, were from 7 to 24 for 3a , from 20 to 37 for 3b , from 34 to 89 for 3c , from 39 to 116 for 3d , from 41 to 145 for 3e , and from 31 to 146 for 3f . It was confirmed that the aggregation property, such as the M_w,SLS or N_agg values, was strongly related to the polymerization degrees of St (DP's) or the number of the glucose residues (n's) for 3a–f . © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4864–4879, 2006