Thermosetting bismaleimide resins generating covalent and multiple hydrogen bonds

Prepolymerizations of 4,4′‐bismaleimidodiphenylmethane (BMI), diallyl isocyanurate (DAIC), and melamine (ML) at 160–170°C and subsequent compression molding at 200–280°C yielded cured BMI/DAIC/ML resins with feed molar ratios of 4/1/1, 3/1/1, and 2/1/1 (BMI‐DAIC‐ML411, 311, and 211). Similarly, cured BMI/DAIC 1/1 and BMI/ML 3/1 resins (BMI‐DAIC11 and BMI‐ML31) were prepared. The FT‐IR analysis revealed that the maleimide and allyl groups were almost consumed for all the cured resins, and the hydrogen bonding interaction became stronger with decreasing BMI contents for BMI‐DAIC‐MLs. Based on the cured structures elucidated from the FT‐IR result, the numbers of multiple hydrogen bonds and cross‐linking covalent bonds (N_MHB and N_CB), and total cross‐linking bond energy (E_TB) were evaluated to be 0, 7.92, and 618 for BMI‐DAIC‐ML411, 0.71, 7.81, and 627 for BMI‐DAIC‐ML311, and 0.95 mol kg^?1, 7.61 mol kg^?1, and 617 kcal kg^?1 for BMI‐DAIC‐ML211, respectively. A higher order of glass transition and 5% weight loss temperatures for BMI‐DAIC‐MLs was 411 > 311 > 211 in accordance with a higher order of N_CB. BMI‐DAIC‐MLs displayed a weak tan δ peak at 70–150°C due to dissociation of the hydrogen bonds. The flexural strength and modulus of BMI‐DAIC‐ML311 were higher than those of BMI‐DAIC‐ML411 in accordance with the difference of E_TB. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43121.     

Textile‐surface interfacial asymmetric polymerization

This research demonstrated that polymerization of aniline on cellulose produces chiroptically active composites. Polymerization of aniline in the presence of cotton fibers consisting of chiral cellulose are performed to prepare a polyaniline (PANI)/cotton composite. The polymerization is conducted at the cotton interface. The resultant PANI/cotton composite shows chiroptical activity elucidated with diffuse reflectance circular dichroism. In this reaction, textile‐surface interfacial asymmetric polymerization is performed with imprinting of chiral structure from the cotton as a natural chiroptically active polymer to the PANI. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41118.     

β‐Cyclodextrin modified cationic acrylamide polymers for flocculating waste drilling fluids

In this article, the P(AM/A‐β‐CD/DMDAAC) is used as flocculant. The synthesis and characterization of the cationic polyacrylamide flocculant modified by β‐cyclodextrin have been studied in the early article. This article stresses its excellent flocculated performance and mechanism. In the flocculated process, the bridging flocculation played a dominant role. Through the flocculation experiments, it can be seen that the flocculating rate of the P(AM/A‐β‐CD/DMDAAC) on four solutions can go up to 93.4%, 89.7%, 85.1%, and 96.7%, respectively. As can be seen from experiment data, the flocculated property of P(AM/A‐β‐CD/DMDAAC) is superior to polyacrylamide and poly (dimethyl diallyl ammonium chloride). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40197.     

Enantioselective Titanium‐Catalyzed Cyanation Reactions of Carbonyl Compounds

This review surveys the recent developments in enantioselective titanium‐catalyzed cyanation reactions of carbonyl compounds, covering the literature since the beginning of 2008. It well demonstrates that this reaction constitutes an important tool in organic synthesis, still attracting a considerable interest due to the potential use of enantiopure cyanohydrins as natural products and useful synthetic intermediates in the synthesis of biologically active molecules. Abbreviations: Ac: acetyl; Ar: aryl; BINOL: 1,1′‐bi‐2‐naphthol; BINOLAM: bis(diethylaminomethyl)‐1,1‘‐binaphthol; Bn: benzyl; Cy: cyclohexyl; DFT: density functional theory; DMAP: 4‐(dimethylamino)pyridine; ee: enantiomeric excess; Naph: naphthyl; r.t.: room temperature; salen: 1,2‐bis(salicylidenamino)ethane; TADDOL: α,α,α′,α′‐tetraphenyl‐2,2‐dimethyl‐1,3‐dioxolane‐4,5‐dimethanol; TEA: trimethylamine; THF: tetrahydrofuran; TMS: trimethylsilyl; Tol: tolyl.

     

电化学手性识别材料的研究与应用

手性是指物质分子互成镜像但无法重合的性质,手性对映体在生物体内因不同的手性识别而呈现截然不同的作用,所以手性识别在生命科学、医药、食品及材料等领域均具有十分重要的科学意义.手性电化学传感器由于具有制备简单、检测快速和响应灵敏等优点而引起广泛的关注.手性识别材料是构建手性电化学传感器的基础,因此有关手性识别材料的研究在手...     

Supramolecular Architectures of Nucleic Acid/Peptide Hybrids

Supramolecular architectures that are built artificially from biomolecules, such as nucleic acids or peptides, with structural hierarchical orders ranging from the molecular to nano-scales have attracted increased attention in molecular science research fields. The engineering of nanostructures with such biomolecule-based supramolecular architectures could offer an opportunity for the development of biocompatible supramolecular (nano)materials. In this review, we highlighted a variety of supramolecular architectures that were assembled from both nucleic acids and peptides through the non-covalent interactions between them or the covalently conjugated molecular hybrids between them.     

Supramolecular Poly(cyclotriphosphazene) Functionalized Graphene Oxide/Polypropylene Composites with Simultaneously Improved Thermal Stability,Flame Retardancy,and Viscoelastic Properties

A novel crosslinkable supramolecular poly(cyclotriphosphazene) functionalized graphene oxide (FGO) is synthesized and melt‐processed with polypropylene (PP), which results in a PP composite with simultaneously improved flame retardancy, smoke‐suppression, and thermal and viscoelastic properties. The cone‐calorimetry test results reveal that the peak heat‐release rate and total heat release of the composite (2 wt% FGO) are reduced by 39.7% and 29.9%, respectively, compared to those of the neat PP. Meanwhile, the total smoke released and total smoke production of PP are significantly (42.7% and 34.9%, respectively) reduced after composite formation with 2 wt% FGO. Similarly, the PP/FGO composite shows an improved maximum weight loss temperature of 392.4 °C, compared to that of neat PP (361.4 °C). Thermogravimetric Fourier‐transform infrared spectroscopy (TG‐FTIR) analysis further confirms that the composite reduces the evolution of the flammable components and toxic gases, especially CO gas, indicating that the FGO significantly decreases the fire hazards of the PP. The thermomechanical and melt‐rheological analyses reveal that the composite has higher mechanical stiffness and viscoelastic properties than the neat polymer. In summary, FGO is shown to have potential as an advanced additive to obtain PP composites with multifunctional properties; however, higher FGO loading would be needed to improve UL‐94 rating from V‐2 to V‐0.     

Diporphyrin tweezer for multichannel spectroscopic analysis of enantiomeric excess

Chiral 1,1’-binaphthyl-linked diporphyrin ‘tweezers’ (R)-1/(S)-1 and the corresponding zinc(II) complexes (R)-2/(S)-2 were prepared as chiral host molecules, and their utility for chiral analyses (especially enantiomeric excess (ee) determinations) were evaluated. Tris(1-n-dodecyl)porphyrins were used for the first time as the interacting units. Host capabilities of the diporphyrin tweezers were investigated by titrations with (R,R)- and (S,S)-cyclohexane-1,2-diamine (CHDA). The host molecules could be used as multichannel probes of ee by using UV-vis, circular dichroism (CD), fluorescence emission and ¹H nuclear magnetic resonance (¹H-NMR) methods. Chiral configurations could also be differentiated using CD or ¹H-NMR spectroscopy. All three optical techniques give good resolution of ee with reasonable sensitivity considering the low concentrations used (ca. 10⁻⁶ mol·L⁻¹). The ee determination of CHDA enantiomers using NMR spectroscopy is also possible because of the reasonably well separated resonances in the case of (R,R)- and (S,S)-CHDA. Non-metallated (R)-1/(S)-1 hosts could not be used to detect chiral information in a strongly acidic chiral guest. This work demonstrates the utility of 1,1’-binapthyl-linked chiral hosts for chiral analysis of ditopically interacting enantiomers.     

一维链状钴配合物的合成、结构及热稳定性

在水热法条件下,以N,N-二甲基甲酰胺（DMF）和水（VDMF∶VH2O=2∶1）为溶剂,基于1,2,4,5-苯四甲酸（H4BTA）、咪唑（Im）和氯化钴（CoCl2.6H2O）合成了一维链状配合物[Co（Im）2（H4BTA）0.5]n（1）。晶体结构分析表明：该配合物属于三斜晶系,P1空间群,在不对称结构单元中一个钴原子与两个咪唑中的两个氮原子、H4BTA中的一个氧原子配位。同时,配合物（1）通过分子间和一维链间氢键作用形成三维超分子。