Heterofunctional RAFT‐derived PNIPAM via cascade trithiocarbonate removal and thiol‐yne coupling click reaction

An efficient one‐pot process to functionalize the α‐ and ω‐positions of RAFT‐derived poly(N‐isopropylacrylamide) (PNIPAM) by two inherently different mechanistic pathways is reported. The method relies on the RAFT polymerization of NIPAM using a new alkyne‐based RAFT agent, namely 2‐cyano‐5‐oxo‐5‐(prop‐2‐yn‐1‐ylamino)pentan‐2‐yl dodecyltrithiocarbonate (COPYDC) and the combination of thiol‐yne click chemistry and thiocarbonylthio chain‐end removal reactions. COPYDC was prepared in good yield and used as an efficient chain transfer agent during the RAFT polymerization of NIPAM. Well‐defined polymers with controlled molar masses ( = 7500–14,700 g.mol^?1) and narrow dispersities (? = 1.18–1.26) are thus obtained. Cascade thiol‐yne click reaction at the alkyne α‐chain end and trithiocarbonate removal at the ω‐chain end are successfully achieved using benzyl mercaptan and excess AIBN. The reported method provides a facile and mild route to heterofunctional telechelic RAFT polymers with predictable molar masses and low dispersities. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3597–3606     

第二结构导向剂诱导形成的二维有机模板稀土硫酸盐

水热条件下合成了具有超大孔道和层状结构的有机模板稀土硫酸盐。超大孔道的稀土硫酸盐（1）的分子式为[（CH₃）₂NH₂]₉[Pr₅（SO₄）₁₂]·2H₂O,它展现出有趣的交叉二十元环孔道结构。层状的稀土硫酸盐的分子式为[H₃O]₃[（CH₃）₂NH₂]₃[Ln₂（SO₄）₆]（Ln=Pr,2;Nd,3）,它可以被看作是由双链和八元环结合而成。这3种化合物的合成揭示了大的有机胺（三聚氰胺）可能用作为第二结构导向剂,阻止形成高维数的无机骨架,从而诱导了二维层状结构稀土硫酸盐晶体的生长。对化合物1和3的磁性进行了研究,测试的温度范围在2~300 K。     

环氧氯丙烷修饰的对位和间位芳纶涂覆剂研究

制备了具有环氧丙基侧链的对位芳纶(PPTA-ECH)和间位芳纶(PMIA-ECH),并将其用做对位芳纶(PPTA)织物/环氧树脂复合材料中PPTA织物的涂覆剂。采用场发射扫描电子显微镜(FE-SEM)及XPS等方法对PPTA织物表面的PPTA-ECH涂层结构进行了表征。考察了PPTA-ECH和PMIA-ECH涂覆的PPTA织物/环氧树脂复合材料的层间剪切强度和面内剪切强度,并与未经涂覆的PPTA织物复合材料的性能作比较。结果表明,PPTA-ECH和PMIA-ECH可显著改善PPTA织物和环氧树脂之间的界面性能。涂覆了PPTA-ECH及PMIA-ECH的PPTA织物/环氧树脂复合材料的层间剪切强度(ILSS)比未经涂覆的复合材料分别提高了26.20%和14.76%,面内剪切强度(ISS)分别提高了26.98%和11.86%。由于PPTA-ECH对PPTA纤维具有更强的亲和能力,因此PPTA-ECH在层间剪切强度和面内剪切强度方面的增强效果均优于PMIA-ECH。对PPTA-ECH在PPTA纤维表面铺展与吸附及对复合材料的增强机理也进行了初步探讨。作为新型涂覆剂,PPTA-ECH在对位芳纶复合材料的开发应用方面具有潜在的应用前景。     

Porphyrin–BODIPY-based hybrid model compounds for artificial photosynthetic reaction centers

In this review, we report the synthesis and photophysical studies of porphyrin–4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) compounds linked either with different covalent bonds or with axial coordination to metalloporphyrin. BODIPY moiety significantly increases the light absorption capability of porphyrins by efficient BODIPY to porphyrin excitation energy transfer. The type of linkage between the two chromophores significantly affects the energy transfer efficiency. The most efficient energy transfer was proved for compounds linked via a cyanuric chloride bridge (∼99% quenching). Therefore, this type of bond seems to be more appropriate choice in constructing porphyrin–BODIPY assemblies for light harvesting applications. Moreover, the functionalization of the conjugates with fullerenes appears to be interesting electron transfer dynamics in the excited state.     

Seed‐Assisted Synthesis of MWW‐Type Zeolite with Organic Structure‐Directing Agent‐Free Na‐Aluminosilicate Gel System

The seed‐assisted synthesis of zeolites without using organic structure‐directing agents (OSDAs) has enabled alternative routes to the simple, environmentally friendly and low‐cost production of industrially important zeolites. In this study, the successful seed‐assisted synthesis of MCM‐22 (MWW‐type) zeolite with an OSDA‐free gel is reported for the first time. MWW‐type zeolites are obtained by the addition of as‐synthesized MCM‐22 seeds prepared with hexamethyleneimine (HMI) into OSDA‐free Na‐aluminosilicate gels. Based on the results of XRD, ICP‐AES, NMR, N₂ physisorption and NH₃‐TPD, the product exhibited different features compared to those of the seeds. The H‐form product can serve as a catalyst in Friedel–Crafts alkylation reaction of anisole with 1‐phenylethanol, and its catalytic activity is comparable to the seeds. Furthermore, XRD, FE‐SEM, TG‐DTA, CHN, FT‐IR and NMR analyses of products and intermediates provide insights into the role of seeds and occluded HMI, the crystallization process, and key factors for achieving seed‐assisted synthesis of MWW‐type zeolites with an OSDA‐free gel system. The present results provide a new perspective for the economical and environmentally friendly production of MWW‐type zeolites.     

高效液相色谱法同时测定纸质食品接触材料中11种荧光增白剂

建立了同时测定纸和纸板食品接触材料中11种荧光增白剂的高效液相色谱–荧光检测法。将粉碎好的纸质样品用40%乙腈水溶液超声提取,脱脂、浓缩后用高效液相色进行定性定量分析。在测定条件下,样品干扰低,11种荧光增白剂分离度大于1.0,在各自线性范围内,相关系数均大于0.999 9,11种荧光增白剂的检出限为0.12~0.24mg/kg,定量限为0.40~0.80 mg/kg,加标回收率为90.1%~99.3%,测定结果的相对标准偏差为0.3%~2.8%(n=6)。该法样品处理简便、快速,方法灵敏度高,重现性好,可用于纸质食品接触材料中荧光增白剂的检测。     

Smart hydrogel sensor for detection of organophosphorus chemical warfare nerve agents

A novel “turn-off” fluorescence, smart hydrogel sensor for detection of a nerve agent simulant has been developed and tested. The smart hydrogel chemosensor has demonstrated an extremely fast and select fluorescence quenching detection response to the Sarin simulant diethylchlorophosphate (DCP) in the aqueous and vapor phases. The fluorogenic sensor utilizes 6,7-dihydroxycoumarin embedded in an polyacrylamide hydrogel matrix as the fluorescent sensing material. The rapid fluorescence quenching of the smart hydrogel films could easily be observed with the naked eye using a hand-held UV light at λ = 365 nm which demonstrates their practical application in real-time on-site monitoring.     

Simple chromatographic detection modes for antitumor agent and its degradants

Degradation of active ingredients is common during the production, transportation, and storage of the pharmaceutical preparations. The resulted degradation products can affect the pharmaceuticals’ therapeutic effect. Also, they may have some toxic properties that make them have deleterious effects on patients. Nifuroxazide, antitumor, antimetastasis, and antidiarrheal agent, has been detected in pharmaceutical formulation by two sensitive, selective, and cheap methods. The first method was densitometric thin-layer chromatography technique. The compound was detected in the presence of its degradation products without any interference. Limits of quantification and detection values were 200 and 94.3?ng/band, respectively. The method was linear in the range 0.2–12?µg/band with mean recovery% ±relative standard deviation (RSD)%?=?99.97%?±?1.414. The second method was developed using simple high-performance liquid chromatography technique. The method was successfully able to separate the proposed compound from its degradation forms in the presence of pentoxiftylline as an internal standard without any interference in less than 5?min. The method also detected nifuroxazide degradation products down to 500?ng/mL. Both methods were statistically compared to a reported method with no significant difference in performance.     

Derivatization of organophosphorus nerve agent degradation products for gas chromatography with ICPMS and TOF-MS detection

Separation and detection of seven V-type (venomous) and G-type (German) organophosphorus nerve agent degradation products by gas chromatography with inductively coupled plasma mass spectrometry (GC–ICPMS) is described. The nonvolatile alkyl phosphonic acid degradation products of interest included ethyl methylphosphonic acid (EMPA, VX acid), isopropyl methylphosphonic acid (IMPA, GB acid), ethyl hydrogen dimethylamidophosphate sodium salt (EDPA, GA acid), isobutyl hydrogen methylphosphonate (IBMPA, RVX acid), as well as pinacolyl methylphosphonic acid (PMPA), methylphosphonic acid (MPA), and cyclohexyl methylphosphonic acid (CMPA, GF acid). N-(tert-Butyldimethylsilyl)-N-methyltrifluroacetamide with 1% TBDMSCl was utilized to form the volatile TBDMS derivatives of the nerve agent degradation products for separation by GC. Exact mass confirmation of the formation of six of the TBDMS derivatives was obtained by GC–time of flight mass spectrometry (TOF-MS). The method developed here allowed for the separation and detection of all seven TBDMS derivatives as well as phosphate in less than ten minutes. Detection limits for the developed method were less than 5 pg with retention times and peak area precisions of less than 0.01 and 6%, respectively. This method was successfully applied to river water and soil matrices. To date this is the first work describing the analysis of chemical warfare agent (CWA) degradation products by GC–ICPMS. Figure Illustrated here are six parent organophosphorus nerve agents corresponding to the degradation products analyzed by gas chromatography with ICPMS and ToF-MS detection. The authors would like to thank Daisy-Malloy Hamburg and Kevin M. Kubachka for creating this figure     

Effects of toughening propylene/ethylene graft copolymer on the crystallization behavior and mechanical properties of polypropylene random-copolymerized with a small amount of ethylene

Linear low-density polyethylene (LLDPE) was grafted onto the backbone chains of isotactic polypropylene (iPP) during reactive melt-extrusion to produce a novel toughening modifier, propylene/ethylene graft copolymer (PEGC), to improve the properties of iPP random(-copolymerized with a small amount of ethylene) (PPR). The crystallization behavior as well as the non-isothermal crystallization kinetics of the PEGC modified PPRs were investigated via differential scanning calorimetry (DSC), polarized optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). The fractured surface topography was characterized using scanning electron microscopy (SEM), and the mechanical properties through notched impact and tensile testing as well as dynamic mechanical thermal analysis (DMTA). The results show that, at a PEGC content of 8 wt%, notched impact strength of the PEGC modified PPR increased by 30.6% at low temperature (−25 °C). As regards crystalline morphology, the PEGC, as an effective heterogeneous nucleating agent, fostered nucleation of the PPR to elevate its crystallization temperature as well as rate of crystallization, thus refining the PPR (iPP) spherulites and improving the interfacial structure between iPP spherulites. The Jeziorny approach was unsatisfactory for simulation of the non-isothermal crystallization process of the PEGC modified PPRs; however, the Mo method described consistently the crystallization kinetics over the entire isothermal process.