水介质中ATRP法制备PDMAEMA及其温敏性

在30℃下以溴化亚铜-溴化铜混合物为催化剂,五甲基二乙烯三胺(PMDETA)为配体,在水介质中利用原子转移自由基聚合法(ATRP)合成聚合度达到300的聚甲基丙烯酸N,N-二甲基氨基乙酯(PDMAEMA)。核磁共振结果显示,聚合反应符合一级反应动力学描述。利用紫外可见分光光度计(UV-Vis)表征该聚合物的温敏性,结果表明,随着PDMAEMA聚合物链长的增加,其最低临界溶解温度(LCST)可降低至31.4℃。     

Photoinduced Specific Acylation of Phenolic Hydroxy Groups with Aldehydes

A convenient method is reported to specifically acylate phenolic hydroxyl groups through a radical pathway. When a mixture of an aldehyde and a phenol in ethyl acetate is irradiated with blue light in the presence of iridium and nickel bromide catalysts at ambient temperature, phenoxyl and acyl radicals are transiently generated in situ and cross‐couple to furnish an ester. Aliphatic hydroxy groups remain untouched under the reaction conditions.     

Synthesis and Crystal Structure of Complex [Pb(qina)2(DMSO)]·H2O

A novel complex [Pb(qina)2(DMSO)]·H2O was synthesized, of which qina- is the quinaldic acid radical and DMSO the dimethyl sulfoxide. Elemental analysis, IR spectra, and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure. This complex belongs to monoclinic system, space group P121/n1, with a = 7.1553(17), b = 17.543(2), c = 17.306(2)(A),β = 91.671(4)°, C22H20N2O6PbS, Mr = 647.65, Z = 4, V= 2171.5(6)(A)3, Dc= 1.981g/cm3,μ = 7.908 mm-1, F(000) = 1248, -9≤h≤6, -23≤k≤ 19, -22≤l≤22, R= 0.0221 and wR =0.0488. Weak coordinate bond is formed between oxygen atom in DMSO and Pb(Ⅱ ). There are also weak interactions, such as π-π interaction, hydrogen bonds and so on, among the complex molecules.     

接枝改性PVDF基含氟聚合物

聚偏氟乙烯(PVDF基)含氟聚合物由于其独特的性能受到了广泛的关注.将功能化链段引入PVDF基含氟聚合物可以进一步提升其性能并拓展其应用领域.相较于物理共混法和直接共聚改性法,通过接枝改性法将功能化单体引入含氟聚合物的侧链具有更显著的优势,可便捷、高效地得到组成精确,结构可控的接枝共聚物.本文综述了通过活性自由基聚合(...     

流动注射邻菲啰啉化学发光体系测定羟自由基

利用Vitc-CuSO4-H2O2产生的羟自由基,建立流动注射邻菲口罗啉化学发光体系测定羟自由基的产生及物质对羟自由基的清除能力。体系中各种物质浓度的最佳组合是:邻菲口罗啉1.0×10-3mol/L(pH 8.2硼砂-硼酸缓冲液配制、内含CTMAB浓度为5.0×10-3mol/L)、Cu2+1.5×10-3mol/L、H2O2体积分数0.6%、抗坏血酸1.5×10-3mol/L。硫脲清除羟自由基的量效关系Y=25.0009ln(x)+65.3120,r=0.9988,IC50=0.542 mmol/L。龙井茶水提液对羟自由基具有较强的清除作用。     

Fe3+-H2O2-Rh6G化学发光体系测定水中的邻苯二酚

酚类化合物对于人体及其他生物的毒性较大,邻苯二酚作为一种重要的有机化工原料和中间体,在农业、染料、香料、橡胶、医药、感光材料等领域具有广泛的应用。因此监测废水中邻苯二酚的含量是控制水环境质量的一个重要指标。目前测定邻苯二酚的方法主要有光度法[1,2],原子吸收法[     

除草剂2-甲基-4-氯苯氧乙酸(MCPA)与OH自由基的气相化学反应

采用长光程气体池结合傅里叶变换红外光谱仪测得了除草剂2-甲基|4|氯苯氧乙酸(MCPA)与·OH自由基在23 ℃时的反应速率常数为2.67×10-11  cm3/(s*mol), 以此估算了在大气中·OH自由基浓度为 7×105  mol/cm3时, MCPA与·OH自由基反应导致的大气寿命为14.9 h. 结果表明, 在大气环境中MCPA较容易降解, 不会通过大气输送对环境造成广泛和持久性污染.      

线型高聚物分子量分布函数的另一种推导方法

针对自由基聚合歧化终止和偶合终止两类机理生成的线型高聚物,应用统计物理的基本原理,对其分子量分布重新进行了理论推导,其方法简洁清晰,无须任何附加假定,导出FlorySchulz分布.结果有助于从另一方面理解FlorySchulz分布的物理学基础.     

MICELLIZATION STUDIES OF DODECYL BENZENESULFONIC ACID AND ITS INTERACTION WITH POLYVINYLPYRROLIDONE

Dodecyl benzenesulfonic acid (DBSA) surfactant was used in the present study to find the effect of concentration on its electrical conductance in solution from 293-323K above and below the critical micelle concentration (CMC). The micellization parameters i.e. degree of counter ion binding (β), aggregation number (n) and number of counter ion micelle(m) were measured. The interaction of DBSA with polyvinylpyrrolidone (PVP) was also studied at 293K throughconductance and surface tension measure ments. A number of important parameters i.e. critical aggregation concentration (CAC), Gibb‘s free energy (△G) and binding ratio (R) were determined and the effect of NaCl on the CAC and polymer saturation point (PSP) was also investigated.     

NARROW-DISPERSED CROSSLINKED CORE-SHELL POLYMER MICROSPHERES PREPARED BY SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION＊

Grafting of polystyrene with narrowly dispersed polymer microspheres through surface-initiated atom transfer radical polymerization (ATRP) was investigated. Polydivinylbenzene (PDVB) microspheres were prepared by dispersion polymerization with poly(N-vinyl pyrrolidone) (PVP) as stabilizer. The surfaces of PDVB microspheres were chloromethylated by chloromethyl methyl ether in the presence of zinc chloride as catalyst to form chloromethylbenzene initiating core sites for subsequent ATRP grafting of styrene using CuCl/bpy as catalytic system. Polystyrene was found to be grafted not only from the particle surfaces but also from within a thin shell layer, resulting in the formation of particles size increased from 2.38-2.58μm, which can further grow to 2.93μm during secondary grafting polymerization of styrene. This demonstrates that grafting polymerization proceeds through a typical ATRP procedure with living nature. All of the prepared microspheres have narrow particle size distribution with coefficient of variation around 10%.