Amphiphilic block copolymer self‐assemblies of poly(NVP)‐b‐poly(MDO‐co‐vinyl esters): Tunable dimensions and functionalities

Functional, degradable polymers were synthesized via the copolymerization of vinyl acetate (VAc) and 2‐methylene‐1,3‐dioxepane (MDO) using a macro‐xanthate CTA, poly(N‐vinylpyrrolidone), resulting in the formation of amphiphilic block copolymers of poly(NVP)‐b‐poly(MDO‐co‐VAc). The behavior of the block copolymers in water was investigated and resulted in the formation of self‐assembled nanoparticles containing a hydrophobic core and a hydrophilic corona. The size of the resultant nanoparticles was able to be tuned with variation of the hydrophilic and hydrophobic segments of the core and corona by changing the incorporation of the macro‐CTA as well as the monomer composition in the copolymers, as observed by Dynamic Light Scattering, Static Light Scattering, and Transmission Electron Microscopy analyses. The concept was further applied to a VAc derivative monomer, vinyl bromobutanoate, to incorporate further functionalities such as fluorescent dithiomaleimide groups throughout the polymer backbone using azidation and “click” chemistry as postpolymerization tools to create fluorescently labeled nanoparticles. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2699–2710     

Phenylsulfonic Acid Functionalized Mesoporous Silica Catalyzed Transetherification of Alcohols with Dimethoxymethane

Phenylsulfonic acid functionalized mesoporous silica was synthesized by condensation of tetraethylorthosilicate with phenyltrimethoxysilane, and then sulfonation using 30% fuming sulfuric acid. The material was characterized using FT‐IR, DSC, XPS, TEM and N2 adsorption/desorption measurements. DSC revealed that sulfonic acid group of the catalyst was decomposed at 354.8°C, indicating that the catalyst exhibited high thermal stability. XPS showed that there existed three kinds of different silicon species on surface of the catalyst. The catalytic performance of the catalyst was evaluated using transetherification of alcohols with dimethoxymethane. It was found that among primary alcohols, the selectivities of the two long‐chain alcohols for n‐dedocanol and n‐tetradecyl alcohol were higher than 97.0% at the conversions of 43.6% and 65.3%, respectively, while the selectivities of the short‐chain alcohols except for n‐hexanol were less than 90.0% at the conversions of over 80.0%. Due to steric barrier, the secondary alcohols such as iso‐butanol and cyclohexanol afforded conversions of 79.4% and 60.5%, and the selectivities of the two alcohols were more than 90.0%. The sequence in conversion of the substituted phenols is as follows: p‐nitrophenol>p‐fluorophenol≥p‐bromophenol>p‐cresol>m‐cresol.     

固体超强酸催化剂SO_4~(2-)/TiO_2-WO_3的制备及其催化性能研究

制备了固体超强酸催化剂SO2 -4/TiO2 WO3 ,并以丁酸丁酯的合成作为探针反应 ,系统考察了WO3 的含量、硫酸浸渍浓度、焙烧温度等制备条件对SO2 -4/TiO2 WO3 催化活性的影响 .实验表明 :制备催化剂的适宜条件为m(H2 WO4) =12 5 % ,硫酸浸渍浓度为 1 0mol·L-1,焙烧温度为 5 80℃ ,活化时间 3h .利用优化条件下制备的催化剂SO2 -4/TiO2 WO3 催化合成缩醛 (酮 ) ,在醛 /酮与二元醇 (乙二醇 ,1,2 丙二醇 )的投料摩尔比为 1∶1 5 ,催化剂的用量占反应物总投料质量的 0 5 % ,反应时间为 1h条件下 ,2 甲基 2 乙氧羰甲基 1,3 二氧环戊烷的收率为 78 7% ,2 ,4 二甲基 2 乙氧羰甲基 1,3 二氧环戊烷的收率为 83 0 % ,环己酮 -乙二醇缩酮的收率为 85 9% ,环己酮 1,2 丙二醇缩酮的收率为 84 6% ,丁酮 -乙二醇缩酮的收率为70 7% ,丁酮 1,2 丙二醇缩酮的收率为 88 3 % ,2 丙基 1,3 二氧环戊烷的收率为 80 6% ,4 甲基 2 丙基 1,3 二氧环戊烷的收率为 79 6% ,2 异丙基 1,3 二氧环戊烷的收率为 64 2 % ,4 甲基 2 异丙基 1,3 二氧环戊烷的收率为 83 3 % ,2 苯基 1,3 二氧环戊烷的收率为 75 3 % ,4 甲基 2 苯基 1,3 二氧环戊烷的收率为 95 1% .     

Comparison of reactivities of 1- and 4-oxotetrahydrocarbazoles in reactions with nucleophilic and electrophilic reagents

The half-wave potentials of polarographic reduction of the carbonyl group in unsubstituted and N-methyl- and N-phenylsulfonyl-substituted 1- and 4-oxotetrahydrocarbazoles and their reactivities in reactions with nucleophilic (NaBH₄, malonodinitrile, and cyanoacetamide) and electrophilic (DMF dimethyl acetal) reagents were compared. 4-Oxotetrahydrocarbazoles are much less reactive than 1-oxotetrahydrocarbazoles. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1832–1836, August, 2005.     

SYNTHESIS OF BLOCK COPOLYMER FROM 5,6 -BENZO-2-METHYLENE-1,3-DIOXEPANE AND METHYL ACRYLATE VIA ATOM TRANSFER RADICAL POLYMERIZATION

Poly(methyl acrylate)-b-poly(5,6-benzo-2-methylene-1, 3-dioxepane) (PMA-b-PBMDO) was synthesized by two-step atom transfer radical polymerization (ATRP). Firstly, ATRP of methyl acrylate (MA) was realized using ethyl α-bromobutyrate (EBrB) as initiator in the presence of CuBr/2,2'-bipyridine. After isolation, poly(methyl acrylate) withterminal bromine (PMA-Br) was synthesized. Secondly, the resulting PMA-Br was used as a macromolecular initiator in theATRP of BMDO. The Structure of block copolymer was characterized by ~1H-NMR spectroscopy. Molecular weight andmolecular weight distribution were determined on a gel permeation chromatograph (GPC).     

Stereoselective routes to substituted β-amino carbonyl compounds via heterodiene [4π+2π] cycloadditions of auxiliary-based C2 symmetric ketene acetals

Heterodiene [4π+2π] cycloadditions of (S,S)-4,5-diaryl-2-methylene-1,3-dioxolanes 1 to a series of β-amido-α,β-unsaturated carbonyl compounds are diastereoselective (d.r.≥4:1). The products can be purified by trituration or crystallisation and hydrolysed with acid to generate the corresponding β-amido carbonyl compounds, the overall sequence effecting an auxiliary-based enantioselective conjugate addition of an acetate enolate, leading to β-aminoacid derivatives.     

The drawing behavior of Y-Ba-Cu-O sol from non-aqueous solution by a complexing process

A complexing process is developed to prepare Y-Ba-Cu-O superconducting fibers. The process is not identical to typical sol-gel processes; here the resulting gel network is built up by hydrogen bonding linkage among complexing species in non-aqueous solution. Cu acetate, [Cu(OAC)₂], Ba methoxyethoxide [Ba(ORE)₂] and Y acetate [Y(OAC)₃] are used as precursors for preparing homogeneous gels while -methacrylic acid (HOAA) and diethylenetriamine (DETA) as complexing agents, and methoxyethanol (REOH) as solvent. Fibers drawn from a sol obtained through reduced pressure present no or little deformation at 80°MoC via adjusting the amount of DETA and HOAA. Cu(OAC)₂, Ba(ORE)₂ and Y(OAC)₃ in the complexing process have been demonstrated to form gels without hydrolysis and condensation at ambient atmosphere. The relationships between the drawing behavior of sols and gel structure with different amounts of DETA and HOAA are suggested. The concentration region of drawing the gel fibers with no or little deformation heated at 80°MoC is also found.     

Synthesis and Characterization of Novel Organosoluble Methyl Substituted Poly(aryl Ether Ketone)s Containing Sulfone Linkage

Several new methyl substituted poly(aryl ether ketone)s containing sulfone linkage with inherent viscosities of 0.62–0.84 dL/g have been prepared from 4,4′‐bis(2‐methylphenoxy)diphenylsulfone and 4,4′‐bis(3‐methylphenoxy)diphenylsulfone with terephthaloyl chloride and isophthaloyl chloride by electrophilic Friedel‐Crafts acylation in the presence of DMF with anhydrous AlCl₃ as a catalyst in 1,2‐dichloroethane, respectively. These polymers having weight‐average molecular weight in the range of 71,000–49,000 are all amorphous and show high glass transition temperatures ranging from 167 °C to 191 °C, excellent thermal stability at temperatures over 400 °C in air or nitrogen, high char yields of 51–58% in nitrogen and good solubility in CHCl₃ and polar solvents such as DMF, DMSO and NMP at room temperature.     

Synthesis and properties of new soluble aromatic polyamides and polyimides on the basis of N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine

A new N‐phenylated amide (N‐phenylamide) unit containing aromatic diamine, N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine, was prepared by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 3‐nitrobenzoyl chloride, followed by catalytic reduction. Two series of organosoluble aromatic poly(N‐phenylamide‐imide)s and poly(N‐phenylamide‐amide)s with inherent viscosities of 0.58–0.82 and 0.56–1.21 dL/g were prepared by a conventional two‐stage method and the direct phosphorylation polycondensation, respectively, from the diamine with various aromatic dianhydrides and aromatic dicarboxylic acids. All polyimides and polyamides are amorphous and readily soluble in many organic solvents such as N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with high tensile strengths. These polyimides and polyamides had glass‐transition temperatures in the ranges of 230–258 and 196–229 °C, respectively. Decomposition temperatures of the polyimides for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2564–2574, 2002     

环状缩醛对某些含官能团烯烃的自由基加成反应

率的加成产物。这些产物通常是不易制备的,因而该反应在这一类酯的合成中将是有效的方法。结果和讨论我们应用的1和含官能团的烯烃2反应,结果列于表1。显然,在体系中存在着多个反应的竞争。要使得上述加成成为主要反应,首先要减少2的自聚和调聚反应,其次要使如下的链反应能够实现(见 p.176)。