Preparation of cinchonine molecularly imprinted photonic crystal film and its specific recognition and optical responsive properties

The cinchonine molecularly imprinted photonic polymer (MIPP) film was prepared by using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross linker, benzoyl peroxide and N,N‐dimethylaniline as initiation system by a combination of colloidal crystal template method and molecular imprinting technique. The structure and morphology of the polymer film were characterized by infrared spectra and scanning electronic microscope. The results exhibit that a highly ordered three‐dimensionally interconnected macroporous array with typical face‐centered cubic (fcc) structure was formed in the MIPP film. The binding experiments showed that the special, hierarchical porous structure enabled this polymer to possess rapid adsorption kinetics, improved binding capacity, and specificity to analytes. The Bragg diffractive measurements showed that the MIPP film has good specific responsiveness for the template molecules. The Bragg diffraction peaks shifted from 527 to 503 nm with the concentration of the cinchonine varying from 0 to 10^?3 mol/L, whereas there were no obvious peaks shifts for its structural analogues. This may be ascribed that the changes in the lattice constants and the average refractive indices of MIPP film caused by the special adsorption of template molecules toward recognition sites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43191.     

Low‐cost,environmentally friendly route to produce glass fiber‐reinforced polymer composites with microfibrillated cellulose interphase

In this article, an easy, effective, and eco‐friendly method to improve the mechanical performance of glass fiber‐reinforced polymer composites is proposed, which involves the coating of unsized glass fiber fabric layers by simple immersion in an aqueous suspension containing sugarcane bagasse microfibrillated cellulose (MFC), followed by vacuum‐assisted liquid resin infusion as the processing method. From atomic force microscopy, a 250 nm MFC‐rich interphase was found, revealing its ability to build micro‐ and nanobridges acting as bulk epoxy matrix and GF linker. The interlaminar shear strength, quasi‐static tensile, and flexural tests, as well as the morphological and fractographic inspection of test coupons containing the secondary substructure, broadly supported the assumption of the efficient role on the interfacial level of this nano reinforcement by enhancing the load transference and distribution from the polymer matrix to the main reinforcing fiber system compared to baseline unsized fiber‐reinforced epoxy laminates. This finding permits this class of composite materials to be considered as having great potential to achieve products with excellent performance/cost ratios. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44183.     

改性Y型分子筛上苯与多乙基苯的液相烷基转移

为获得高性能的液相烷基转移反应催化剂,采用不同的方法对Y型分子筛进行改性处理。采用N_2吸附-脱附、程序升温脱附(NH_3-TPD)和吡啶吸附红外(Py-IR)等手段对样品进行了表征,并在连续微型固定床反应器中考察了改性Y型分子筛上苯和多乙基苯烷基转移反应的催化性能。结果表明,催化剂的烷基转移反应性能与Y型分子筛的孔道和B酸量有密切的关系。通过铵离子交换和酸处理改性均可以提高催化剂的B酸量、比表面积、孔容和孔径;水蒸汽处理会降低酸量;铵离子交换和酸处理复合改性的Y型分子筛催化性能最好。适宜的反应条件为:反应温度180~240℃,反应压力2.5~4.0 MPa,总物料重量空速3~5 h~(-1),苯与二乙苯的质量比2~4,在该条件下二乙苯转化率大于65%,乙基选择性大于98%。该催化剂性能稳定,1 000h运行后活性仍没有下降。     

丙烯酰胺在聚乙二醇水溶液中可逆加成-断裂链转移聚合

结合双水相聚合和可逆加成-断裂链转移(RAFT)聚合,提出在聚乙二醇(PEG)水溶液中进行丙烯酰胺(AM)的RAFT双水相聚合,考察反应条件对聚合反应速率和产物分子量及分布的影响。结果表明:高引发剂浓度、单体浓度和聚合温度可以提高初始聚合速率和最终转化率,PEG和RAFT试剂浓度的增加会导致聚合速率减慢和最终转化率降低;峰值聚合速率随引发剂浓度、单体浓度和聚合温度的增加而增大,同时峰值聚合速率对应的时间提前;RAFT试剂浓度增加会推迟峰值聚合速率对应的时间,但可制得分子量分布较窄的产物;PEG浓度的增加会导致产物的分子量分布变宽。     

煤层气浓缩用碳分子筛的研制及性能研究

为评价分析碳分子筛(Carbon Molecular Sieves,CMS)产品性能,以酚醛树脂废料为主要原料,通过添加助剂,采用炭化/气相沉积一体化工艺,制备了专用于煤层气提浓的BM碳分子筛(记为BMCMS)。采用CO_2吸附法、加压热重法及四塔变压吸附法对BMCMS及商业碳分子筛(记为JCCMS)的孔隙结构、CH_4和N_2的吸附容量、速度以及对煤层气的实际分离性能等进行研究。结果表明,BMCMS碳分子筛的孔隙以0.85 nm以下微孔为主,主要分布在0.4~0.65 nm,其比例占整个孔隙的66%以上,高于JCCMS的65%;碳分子筛的孔隙直径为N_2分子的1.1~1.8倍时,该类孔隙适宜吸附N_2,而对CH_4的吸附具有阻碍作用;当用于PSA浓缩抽采煤层气时,可将煤层气中CH_4浓度提高25.6%,实际运行指标优于JCCMS。     

The role of conductive pathways in the conductivity and rheological behavior of poly(methyl methacrylate)–graphite composites

Up to now, research on the dynamic process of conductive network formation has tended to focus on composite particles with one‐dimensional geometry, such as carbon black and carbon nanotubes. However, studies on this subject based on fillers with two‐dimensional structure, such as graphite, are rare in the literature. In this work, the dynamic percolation and rheological properties of poly(methyl methacrylate) (PMMA)–graphite composites under an electric field were investigated. The activation energies of conductive network formation and polymer matrix mobility were calculated from the temperature dependence of the percolation time and the zero‐shear viscosity. It was found that the activation energy calculated from the zero‐shear viscosity was not influenced by the electric field in the concentration range investigated, but the electric field had an effect on the activation energy calculated from the percolation time. This finding emphasizes that the electrical and rheological properties have different physical origins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43810.     

Sweet potato amylose and amylopectin with narrower distribution of molar mass and chain length obtained by a repeated retrogradation–hydrolysis procedure

The wide molar mass distribution of native starch creates obstacles in investigating the physicochemical characteristics of starch, such as retrogradation, because samples thought to be the same are actually compounds containing many chains with different molar masses. In this paper, the sweet potato amylose and amylopectin isolated from retrograded starch were treated with the retrogradation–hydrolysis method three times, and their physicochemical changes in this process were determined by absorbance of the starch–iodine complex, light microscopy, and molar mass and chain length distributions. The results showed that repeated retrogradation and hydrolysis caused the molar mass distribution of sweet potato amylose and amylopectin to reduce from 4.2 × 10⁷–205 and 7971–223 to 6.0 × 10⁴–730 and 4533–211 g mol⁻¹, respectively. This retrogradation–hydrolysis cut the chain length distribution of sweet potato amylose from DP 9–35 to DP 3–13, but that of amylopectin remained unchanged. The double helix in sweet potato amylopectin will not form if the percentage of chain length with DP ≥ 4 is less than 25%. Repeated retrogradation and hydrolysis was an appropriate method to obtain amylose or amylopectin with a narrower molar mass distribution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43849.     

Self-disproportionation of Enantiomers (SDE) of Chiral Nonracemic Amides via Achiral Chromatography

This article is based on a review of literature devoted to the phenomenon of SDE via achiral chromatography since the appearance of the seminal work of Professor Emanuel Gil-Av. The discussed examples of chromatographic studies are related to amides derived from chiral amines and α- and β-amino acids. We discuss the observed SDE magnitude as a function of a compound's structure, and composition of eluent and stationary phases, providing some mechanistic considerations. Particular emphasis is given to the aspect of SDE via achiral chromatography as an emerging unconventional enantiomeric purification technique.     

Molecular dynamics simulations of molecularly imprinted polymer approaches to the preparation of selective materials to remove norfloxacin

A novel molecularly imprinted polymer (MIP) designed by molecular dynamics (MD) simulations was successfully prepared with norfloxacin as a template molecule, methyl acrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a crosslinker. According to the theoretical prediction and experimental preparation methods, three kinds of molecular imprinting materials were designed and synthesized with MD simulations and molecular imprinting technology. The best ratio of the template to the functional monomer to the crosslinker was 1:8:40 in these studies. The experimental results illustrate that the MD simulations were credible in compounding the components of the MIPs. The structure of the prepared polymers were characterized with various methods. To analyze the adsorption performances, many kinds of static adsorption tests, including kinetic, isotherm, and selectivity tests, were used. The results indicate that the novel adsorbents conformed to the pseudo–second‐order kinetic equation and followed the Langmuir isotherm model. The adsorption amounts of MIP2 at a ratio of 1:8:40 were about 29.35 mg/g at 298 K_. The selective adsorption and reusable performance of norfloxacin were excellent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42817.