Stress-Strain Behavior of Shape Memory Polymers by 1WE Method: Application to Tecoflex®

Thermomechanical cycles including programming, cooling, unloading and heating to trigger the 1WE were examined for a shape memory polymer (SMP), Tecoflex® (TFX EG-72D). Cycles were performed at 60°C with 50% and 225% strains and the recovery time of 10 min. Strains evolving with time were estimated during the thermomechanical treatments for the total 44 cycles using 50% strains and the total 50 cycles using 225% strains. Recovery ratios for 50% strains and 225% were also estimated. It turns out that programming, cooling, unloading and heating to trigger the 1WE causes an increase of irreversible strain and is associated with a corresponding decrease of the intensity of the 1WE in particular during the first thermomechanical cycles. In parallel scanning electron microscopic study using secondary electron imaging shows a very slight wavy surface structure evolved during cycling.     

A New Method to Synthesize the P,N-Heteromultifunctional Ligands

The nature of the highly polar P-N bond in phosphinimine makes a ligand of this kind become versatile in both coordination and organometallic chemistry.[1,2] Usually this kind of phosphinimine phosphine P,N-heterodifunctional ligands is prepared by the Staudinger reaction of azides with organophophine. Now a more mild and efficient method is provided. The product of Mannich reaction of 2-aminopyridine reacted with Ph2PCl in the presence of Et3N, giving the phosphinimine compound 1 in more than 90% yield.     

Uniformly Sized Molecularly Imprinted Polymers: Their Applications to Chiral Separation and Bioanalysis

Molecularrecognition playsanimportantroleinbiologicalandchemicalprocesses .Sincemolecu larimprintingtechniquescanaffordcomplementarybindingsitesforatargetmolecule ,themolecularlyimprintedpolymer (MIP)forthetargetmoleculehasbeenusedforitsspecificrecognitio…     

From Disymmetric Molecules to Chiral Polymers: A New Twist for Supramolecular Synthesis?

A new branch of crystal engineering appears to have borne fruit: A noncovalently bonded network consisting of the complex illustrated as a stick model on the right is converted directly into a coordination polymer with a similar molecular architecture. The implications of the new work extend beyond the boundaries of coordination chemistry since the same strategy should work equally well in organic and organometallic systems.     

Barrier Properties OF Inorganic-Organic Polymers: Influence of Starting Compounds,Curing Conditions and Storage-Scaling-Up to Industrial Application—

With a new kind of barrier coating material, namely inorganic-organic polymers, it is possible to obtain high-barrier properties for oxygen, water vapor, and flavor permeation. These hybrid polymers can be synthesized by the sol-gel technique. Network forming reactions and degrees of condensation in the coating sols as well as in the cured coating materials were characterized using ²⁹Si, ¹³C-NMR and FT-Raman spectroscopy. The oxygen barrier properties of the hybrid polymers were found to be strongly influenced by the inorganic and also by the organic network density. In order to scale-up the excellent laboratory results to pilot plant and production dimensions additional efforts were necessary. For optimization of the barrier coating compositions the influence of the starting compounds on the resulting barrier properties had to be investigated. A constant quality of the coating sols during the industrial processing had to be guaranteed so as to obtain reproducible barrier properties. The influence of storage conditions on chemical reactions in the coating sols, indicated by changes of viscosity, was investigated. Since the curing times of the laboratory system were not transferable to the high speed of the production roll coating process more effective curing methods had to be found. The influence of the storage time of the cured coating materials on the oxygen barrier properties was investigated. Even by storing at ambient temperature further improvement of the oxygen barrier properties was obtained. Only by optimizing all of the above mentioned parameters can the excellent barrier properties result in marketable products.     

A Facile Method for Monoesterification of α, ω-Dicarboxylic Acids: Application to the Synthesis of Traumatic Acid,A Prostaglandin Synthon

During the past decade, methyl 7-(5-oxocyclopentenyl)heptanoate (6) has been frequently used as a key intermediate in prostaglandin synthesis.¹ Although keto ester 6 can be readily obtained by treatment of traumatic acid (5) with polyphosphoric acid followed by esterification with methanolic hydrochloric acid,² this approach is not attractive for large-scale synthesis due to the expense of the latter natural product (5). Recently Salomon and Reuter have reported¹ an alternate route to synthon 6 based on a starting material derived from aleuritic acid, a major component of shellac.     

Reactive Dye Removal Using Inorganic–Organic Composite Material: Kinetics,Mechanism, and Optimization

An inorganic–organic composite material (MCPAM) consisting of magnesium chloride and polyacrylamide, was applied to remove reactive dye (Cibacron Red FN-R) from aqueous solution through coagulation–flocculation process. MCPAM with the ratio of 90% MgCl₂/10% PAM was the best ratio in removing reactive dye. Kinetics of reactive dye removal was investigated using pseudo-kinetics model and it fits pseudo-second-order reaction model. The mechanism of reactive dye removal was investigated through physicochemical properties of supernatant, flocs, and sludge. The change of conductivity and pH denotes the interactions between reactive dye and MCPAM. The chemical structure, settling, and microstructure of sludge indicate the formation of sludge during coagulation–flocculation process. The settled sludge volume and sludge volume index (SVI) that of MCPAM was lower than that of MgCl₂. The flocs formed using MCPAM was also relatively compact and larger in size compared to that of MgCl₂. The reactive dye removal was optimized through central composite design whereby color removal (%) and chemical oxygen demand (COD) reduction (%) were optimized by five operating factors, namely, concentration of dye, pH, dosage of MCPAM, agitation speed, and agitation time. The optimal values reported for color removal (%) and COD reduction (%) were of 97–98% and 60–81%, respectively.     

A Sensitive LC�CMS�CMS Method for Simultaneous Quantification of Two Structural Isomers, Hyperoside and Isoquercitrin: Application to Pharmacokinetic Studies

We report the development and validation of a rapid, specific, and sensitive liquid chromatographic?Ctandem mass spectrometric (LC?CMS?CMS) method for analysis and pharmacokinetic study, in rats, of hyperoside and isoquercitrin, two bioactive structural isomers present in the leaves of Apocynum venetum L. After simple deproteinization by addition of acetonitrile, the analytes were separated on a C₁₈ column. Detection was by tandem mass spectrometry in multiple reaction monitoring mode. The method was linear over the concentration range 3.9?C195 ng mL^?1 for both hyperoside and isoquercitrin. Intra-day and inter-day precision for both hyperoside and isoquercitrin were <13.1%, and relative errors were all within 7.1% at all QC levels. The method was used to study the pharmacokinetic performance of the compounds after oral administration of an extract of Apocynum venetum L. leaves to rats.     

Isoregic Thienylene‐Phenylene Polymers: The Effects of Structural Variation and Application to Photovoltaic Devices

Isoregic conjugated polymers composed of thiophene and dialkoxybenzene units were designed to harvest incident light in the mid‐visible energy range (band gap of 2.1 eV). Poly(1,4‐bis(2‐thienyl)‐2,5‐diheptoxybenzene) (PBTB(OC₇H₁₅)₂) and poly(1,4‐bis(2‐thienyl)‐2,5‐didodecyloxybenzene) (PBTB(OC₁₂H₂₅)₂) have shown significant photovoltaic performance as an electron donor when used in tandem with the electron acceptor [6, 6]‐phenyl C₆₁‐butyric acid methyl ester (PCBM) in bulk hetero‐junction photovoltaic devices. Photovoltaic devices incorporating PBTB(OC₇H₁₅)₂ and PCBM have shown AM1.5 efficiencies of ～0.6% with a short circuit current density of 2.5 mA/cm², an open circuit voltage of 0.74 V, and a fill factor of 0.32. Incident Photon‐to‐Current Efficiency (IPCE) of the device was found to be ca. 16% at 410 nm. In order to examine the relationship between the molecular structure of the polymers and their electronic energy levels, and to correlate this with photovoltaic performance, optoelectronic and electrochemical results are discussed in relation to the I‐V characteristics of the devices. Additionally, a computer‐aided simulation is used to gain further insight into the effect of polymer structure on the energetic relationships in the bulk heterojunction devices.     

Two Interpenetrated and Polycatenated Zn(Ⅱ) Coordination Polymers: Syntheses,Structures and Luminescent Properties

Two fascinating Zn(II)entangled coordination polymers,[Zn(eoba)(bbi)]_n·nH_2O(1)and[Zn(boba)(bbi)_(1/2)]_n(2),(bbi=1,1?-(1,4-butanediyl)-bis(imidazole),H_2eoba=4,4?-(ethane-1,2-diyldioxy)-dibenzoic acid,H_2boba=4,4?-(butane-1,4-diyldioxy)-dibenzoic acid),were obtained by hydrothermal technology and characterized by elemental analysis,infrared spectrum,thermogravimetric analysis and single-crystal X-ray diffraction.1 is a rare 2D→3D example with a 3-fold parallel interpenetration and polycatenaned architecture.2 features a scarce2D→2D example with a 3-fold parallel interpenetrating network which possesses polyrotaxane and polycatenane characters.Moreover,the luminescent properties of 1 and 2 have been discussed.     

Preparation and Properties of Elastomer Composites Containing “Graphene”-Based Fillers: A Review

Elastomers are materials showing exceptional elasticity and are used for numerous applications. However, their low stiffness as well as their insulating behavior can be limiting so the incorporation of graphene-based materials can help and improve drastically their properties. With high Young's modulus, high electrical and thermal conductivities, graphene and graphene-like fillers seem ideal fillers to effectively tune elastomers properties. With low graphene-like loadings, most elasticity properties of elastomers could be preserved while increasing or adding new properties to the composites to enable new applications. Herein, we focus on the effects of “graphene” incorporation into elastomers and we will highlight the key parameters to effectively monitor the changes.     

A Review of: “Natural and Synthetic Polymers by Henry L Bolker Marcel Dekker,Inc., New York, 1974”

Grafting to fibers has been studied extensively since the early 1950s as a technique for modifying their properties. Extensive reviews are available on this general subject [l-41. Although the main emphasis has been with textile fibers, considerable work has also been carried out with paper-making fibers and on paper itself [l,5].     

A Novel and Facile Method to Synthesize (R)‐ and (S)‐2‐methylpiperazine

Abstract

A concise and efficient synthesis of (R)‐ and (S)‐2‐methylpiperazine in only five steps from (D)‐ and (L)‐alanine is described. The key step is reaction of benzylamine with a bifunctional molecule to build a six‐membered ring.     

A Sensitive LC–ESI–MS–MS Method for the Determination of Huperzine A in Human Plasma: Method and Clinical Applications

A sensitive and specific liquid chromatography–electrospray ionization–tandem mass spectrometry method has been developed and validated for the quantification of huperzine A in human plasma. After the addition of trimetazidine, the internal standard (IS) and sodium hydroxide, plasma samples were extracted using 5 mL ethyl acetate. The compounds were separated on an Agilent Zorbax SB C₁₈ column (100 mm × 2.1 mm ID, dp 3.5 μm) using an elution system of 10 mM ammonium acetate solution–methanol–formic acid (18:82:0.1, v/v) as the mobile phase. The quantification of target compounds was obtained by using multiple reaction monitoring (MRM) transitions: m/z 243.1, 210.1 and 267.2, 166.0 were measured in positive mode for huperzine A and IS. Linearity was established for the range of concentrations 0.01–4.0 ng mL^?1 with a coefficient of correlation (r) of 0.9991. The lower limit of quantification (LLOQ) was identifiable and reproducible at 0.01 ng mL^?1. The method has been successfully applied to study the pharmacokinetics of huperzine A in healthy male Chinese volunteers.     

Regioselective Sequential Additions of Nucleophiles and Electrophiles to Perfluoroalkylfullerenes: Which Cage C Atoms Are the Most Reactive and Why?

The sequential addition of CN^? or CH₃^? and electrophiles to three perfluoroalkylfullerenes (PFAFs), C_s‐C₇₀(CF₃)₈, C₁‐C₇₀(CF₃)₁₀, and C_s‐p‐C₆₀(CF₃)₂, was carried out to determine the most reactive individual fullerene C atoms (as opposed to the most reactive C?C bonds, which has previously been studied). Each PFAF reacted with CH₃^? or CN^? to generate metastable PFAF(CN)^? or PFAF(CH₃)₂^2? species with high regioselectivity (i.e., one or two predominant isomers). They were treated with electrophiles E⁺ to generate PFAF(CN)(E) or PFAF(CH₃)₂(E)₂ derivatives, also with high regioselectivity (E⁺=CN⁺, CH₃⁺, or H⁺). All of the predominant products, characterized by mass spectrometry and ¹⁹F NMR spectroscopy, are new compounds. Some could be purified by HPLC to give single isomers. Two of them, C₇₀(CF₃)₈(CN)₂ and C₇₀(CF₃)₁₀(CH₃)₂(CN)₂, were characterized by single‐crystal X‐ray diffraction. DFT calculations were used to propose whether a particular reaction is under kinetic or thermodynamic control.     

Small-Molecule Modulation of Soft-Matter Frank–Kasper Phases: A Method for Adding Function to Form

Incorporation of small amounts of α-tocopherol (vitamin E) in blends with the cellobiose–triazole-linked atactic poly(4-methyl-1-pentene) (CB-aPMP) sugar–polyolefin conjugate can be used to exert external control over thermotropic phase behavior and provide access to non-canonical soft matter Frank–Kasper A15 and σ phases. These results establish a paradigm that can be used for the further design and development of scalable quantities of soft matter FK phases of increased structural complexity and functional capability.     

Properties in Reactive Structure Materials: ZrW2 and HfW2 – High Melting Temperatures,Densities, Hardness,and Exothermic Ignition Energies

ZrW₂ and HfW₂ were prepared by melting the constituent elements in an arc-furnace. By cooling through perictectic phase lines above approximately 2000 °C, samples of the nominal 1:2 composition were obtained as products consisting of two phases, of which approximately 95 % adopts the MgCu₂ type structure and 5 % the W structure. In ZrW₂ and in HfW₂, the MgCu₂ type structure enables efficient topological compact spacefilling of the smaller W atoms into the cavities of the three-dimensional net constructed by the larger tetravalent metals Zr and Hf. Correspondingly, very dense and hard alloys are obtained which burn at a crash in air in a strong exothermic ignition reaction. These materials are non-toxic.