New fluorous bipyridine ligands for copper‐catalyzed atom transfer radical polymerization of methyl methacrylate in the thermomorphic mode

The atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) is often carried out under homogeneous conditions, so the residual metal catalyst in the polymer often influences the quality of the polymer and causes environmental pollution in the long run. Novel CuBr/4,4′‐bis(R_fCH₂OCH₂)‐2,2′‐bpy complexes (R_f = n‐C₉F₁₉, n‐C₁₀F₂₁, or n‐C₁₁F₂₃; 2,2′‐bpy = 2,2′‐bipyridine) are insoluble in toluene at room temperature yet readily dissolve in toluene at elevated temperatures to form homogeneous phases for use as catalysts in the ATRP reaction, and the Cu complexes precipitate again upon cooling. The CuBr/4,4′‐bis(n‐C₉F₁₉CH₂OCH₂)‐2,2′‐bpy system produced the best results (e.g., polydispersity index by gel permeation chromatography = 1.26–1.41), in that the residual Cu content in the polymer was as low as 19.3 ppm when the ATRP of MMA was carried out in the thermomorphic mode. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Comparative study of three lignin fractions isolated from mild ball‐milled Tamarix austromogoliac and Caragana sepium

Six lignin fractions from mild ball‐milled Tamarix austromogoliac (TA) and Caragana sepium (CS) were sequentially isolated with 80% dioxane containing 0.05M HCl at 75°C for 4 h, 50% aqueous ethanol containing 1M triethylamine at 70°C for 4 h, and 8% aqueous NaOH at 45°C for 3 h. The results showed that the successive treatments made it possible to isolate lignin from wood with a high yield and purity, in which 89.4 and 90.6% of the original lignin from TA and CS were released, respectively. The lignin fractions isolated with the three‐step method were analyzed with Fourier transform infrared, ¹H‐ and ¹³C‐NMR, alkaline nitrobenzene oxidation, and gel permeation chromatography. It was found that the three lignin fractions isolated from TA were rich in syringyl units, and the molar ratio of the relatively total moles of vanillin, vanillic acid, and acetovanillin to the relatively total moles of syringaldehyde, syringic acid, and acetosyringone decreased from 1: 2.6 to 1 : 3.2 to 1: 3.6 in the lignin preparations, whereas this ratio in the corresponding lignin fractions isolated from CS was found to be 1.4 : 1, 1.1 : 1, and 1 : 1.4, respectively. More importantly, the results revealed that the sequential extractions of the mild ball‐milled TA and CS with 80% acidic dioxane, 50% alkaline ethanol, and 8% aqueous NaOH under the conditions used did not significantly cleave the β–O‐4 and α–O‐4 linkages in lignin macromolecules. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of the cosurfactant 1‐butanol and feed composition on nanoparticle properties produced by microemulsion copolymerization of styrene and methyl methacrylate

The concentration of the cosurfactant 1‐butanol (BuOH) determined the polymer weight and size for a series of poly(styrene‐co‐methyl methacrylate)s (P(St‐co‐MMA)) synthesized by the free‐radical (o/w) microemulsion technique. A factorial design established the levels of the experimental conditions for the polymerization i.e., concentration of the surfactant, sodium dodecyl sulfate (SDS); concentration of the cosurfactant, BuOH; temperature and ratio of the styrene (St) to methyl methacrylate (MMA). An increase in the weight‐average molecular weight (M_w) and number‐average molecular weight (M_n) was observed in the P(St‐co‐MMA) series with an increase in BuOH concentration from 1 to 5 wt %. These effects could arise from the micellar aggregation induced by interfacial BuOH. The unique micellar conditions could be exploited to synthesize copolymers of varying molecular weight and size. Additionally, the composition of the copolymers was virtually templates of the feed composition. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

用LC/APCI/MS方法检测粉尘中的炸药成分

采用高选择性和灵敏度的LC(液相色谱)/APCI(大气压化学电离源)/MS(质谱)方法定量分析粉尘样品中的HMX、RDX、PETN、CE、NQ和TNT。采用ASE萃取,GPC净化浓缩作为前处理方法,在粉尘中分别添加所测炸药组分,用丙酮作为ASE萃取溶剂,乙酸乙酯和环己烷(体积比为1∶1)作为GPC净化时的流动相并抛弃杂质500s,收集1 520s。在LC/MS分析时,通过在流动相中添加1mmol/L甲酸与样品形成[M+HCOO]-的甲酸加合离子。结果表明,HMX、RDX、PETN、CE、NQ、TNT的方法检测限分别为0.78,1.44,1.69,0.77,1.06,1.72ng/mL,回收率为49.0%～88.4%,相对标准偏差为3.5%～10.3%。该方法可以用来系统排查及定量分析爆炸残留物及环境样品中的NQ、RDX、PETN、CE、HMX、TNT成分。     

凝胶渗透色谱(GPC)表征聚丙烯相对分子量及其分布的方法研究

本文研究了一种凝胶渗透色谱表征聚丙烯树脂相对分子质量及其分布的方法,并将本方法的重复性、准确度与ASTM标准进行了对比,与文献方法进行对比.结果表明,本方法表征聚丙烯树脂相对分子质量及分布重复性好,准确度高.     

对苯二酚-果糖树脂的合成与表征

在碱性条件下,使用果糖代替甲醛与对苯二酚反应,成功地制备出环境友好型的对苯二酚-果糖树脂。利用红外、GPC、TGA等对所合成的树脂进行了表征。同时使用响应面优化法优化了反应条件,最优反应条件为:催化剂用量3.99%、反应温度69.97℃、反应时间9.03h、n果糖:n对苯二酚=9.29:1。最优条件时的黏度为222.808mPa?s,拉伸强度15.71～23.61MPa。     

GPC法测定煤基、石油基聚丙烯分子量及分布

采用GPC法测定神宁化工生产的均聚聚丙烯牌号（1#）及国内市场上两个同类牌号（2#、3#）的分子量大小及其分布,结果表明1#样品分布最窄;三者在三氯苯溶液中,150℃时具有良好的溶解性,在溶液中的分布状态基本一致。与2#、3#相比,1#样品的分子量分布更窄,更适合用做拉丝料,保证丝带不断丝,稳定生产。     

再生剂对沥青相对分子质量和尺寸分布的作用

分析了3种再生剂对3种老化沥青的再生作用,以探究再生过程对沥青相对分子质量和分子尺寸分布的影响.首先,通过分子凝胶色谱（GPC）分析了沥青再生前后相对分子质量分布的变化;然后,通过动态剪切流变（DSR）仪获得沥青再生前后的主曲线,并计算得到相应的沥青松弛谱图（CRS）和分子尺寸分布的变化;最后,对沥青相对分子质量分布、沥青分子尺寸分布与沥青物理性质的关联进行了分析讨论.结果表明：再生剂对老化沥青大尺寸分子存在降解作用和稀释作用,且2种作用受老化沥青种类和再生剂种类的影响;沥青再生过程中,再生剂对沥青大尺寸分子的分散效果与沥青的宏观软化效果存在很强的正相关关系.     

凝胶渗透色谱-高效液相色谱串联质谱法测定 咸鱼中7种有机磷农药

目的 建立咸鱼中丙溴磷、毒死蜱、马拉硫磷、亚胺硫磷、三唑磷、敌百虫和乐果等七种有机磷农药的凝胶渗透色谱-高效液相色谱串联质谱测定法。方法 咸鱼样品经环己烷-乙酸乙酯(1:1, v/v)提取后,经凝胶渗透色谱仪净化,再使用Extend-C18色谱柱分离,采用电喷雾离子化源,以多反应监测（MRM）方式分析,正离子化模式进行检测。结果 七种有机磷农药在2.5～100 μg/kg线性范围内的相关系数良好,其检出限在0.05～0.20 μg/kg之间。该方法加标回收率为70.9%～116.6%,相对标准偏差为2.7%～13.8%（n=6)。结论 本方法具有提取效率高,净化效果好,准确灵敏和快速等优点,适用于咸鱼中有机磷农药残留检测,符合实际工作的需要。     

Synthesis and photovoltaic properties of an alternating phenylenevinylene copolymer with substituted-triphenylamine units along the backbone for bulk heterojunction and dye-sensitized solar cells

We have fabricated bulk heterojunction (BHJ) photovoltaic devices based on the as cast and thermally annealed P:[6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) blends and found that these devices gave power conversion efficiency (PCE) of about 1.15 and 1.60% respectively. P is a novel alternating phenylenevinylene copolymer which contains 2-cyano-3-(4-(diphenylamino)phenyl)acrylic acid units along the backbone and was synthesized by Heck coupling. This copolymer was soluble in common organic solvents and showed long-wavelength absorption maximum at 390-420 nm with optical band gap of 1.94 eV. The improvement of PCE after thermal annealing of the device based on the P:PCBM blend was attributed to the increase in hole mobility due to the enhanced crystallinity of P induced by thermal treatment. In addition, we have fabricated BHJ photovoltaic devices based on the as cast and thermally annealed PB:P:PCBM ternary blend. PB is a low band gap alternating phenylenevinylene copolymer with BF₂-azopyrrole complex units, which has been previously synthesized in our laboratory. We found that the device based on this ternary blend exhibited higher PCE (2.56%) as compared to either P:PCBM (1.15%) or PB:PCBM (1.57%) blend. This feature was associated with the well energy level alignment of P, PB and PCBM, the higher donor-acceptor interfaces for the exciton dissociation and the improved light harvesting property of the ternary blend. The further increase in the PCE with thermally annealed ternary blend (3.48%) has been correlated with the increase in the crystallinity of both P and PB. Finally, we used copolymer P as sensitizer for quasi solid state dye-sensitized solar cell and we achieved PCE of approximately 3.78%.