Nanodiamond tethered epoxy/polyurethane interpenetrating network nanocomposite: Physical properties and thermoresponsive shape-memory behavior

In this study, a novel blend of polyurethane and diglycidyl 1,2-cyclohexanedicarboxylate epoxy was prepared and reinforced with various content of functional nanodiamond (0.1–5 wt%). According to morphological analysis, diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond nanocomposite revealed beaded-twine network structure due to entrapment of nanodiamond aggregates into epoxy/polyurethane interpenetrating networks. Exclusive self-assembled nanodiamond-tethered interpenetrating network was due to physical inter-linking of nanodiamond with blend components. There was a 47% rise in tensile strength and an 80% increase in Young’s modulus of diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond 5 nanocomposite relative to neat polymer. The original shape of diglycidyl 1,2-cyclohexanedicarboxylate/polyurethane/nanodiamond 5 was 95% recovered using heat-induced shape-memory effect.     

Compatibilizing effect of functionalized polystyrene blends: a study of morphology,thermal, and mechanical properties

Polystyrene (PS), being an amorphous polymer is immiscible with other polymers. To engender miscible blends, PS has been functionalized with an active amino‐functional group on the molecular chains of PS to yield amino‐substituted polystyrene (APS), which serves as a reactive compatibilizer. The compatibilization effect of amino functionalized polystyrene on the rubber toughening was explored and results were compared in terms of morphology, thermal, and mechanical properties of PS/SEBS‐g‐MA versus APS/SEBS‐g‐MA blends. In addition, the effect of rubber content on the blend morphology and mechanical properties were investigated. An appreciable change in the thermal stability of APS blends in comparison with PS blend has been probed. A marked correlation has been observed between phase morphology and thermal stability. Use of APS produced the compatibilized blends which render improved blend morphology, enhanced thermal and mechanical properties. Optimal thermal, morphological and mechanical profiles were depicted by 20‐wt% APS blend. Copyright © 2008 John Wiley & Sons, Ltd.     

Reactions of rhenium and manganese carbonyl complexes with 1,8-bis(diphenylphosphino)naphthalene: Ligand chelation, C-H and C-P bond-cleavage reactions

Reaction of [Re₂(CO)₈(MeCN)₂] with 1,8-bis(diphenylphosphino)naphthalene (dppn) afforded three mono-rhenium complexes fac-[Re(CO)₃(κ¹:η¹-PPh₂C₁₀H₆)(PPh₂H)] (1), fac-[Re(CO)₃{κ¹:κ¹:η¹-(O)PPh₂C₁₀H₆(O)PPh(C₆H₄)}] (2) and fac-[ReCl(CO)₃(κ²-PPh₂C₁₀H₆PPh₂)] (3). Compounds 1-3 are formed by Re-Re bond cleavage and P-C and C-H bond activation of the dppn ligand. Each of these three complexes have three CO groups arranged in facial fashion. Compound 1 contains a chelating cyclometalated diphenylnaphthylphosphine ligand and a terminally coordinated PPh₂H ligand. Compound 2 consists of an orthometalated dppn-dioxide ligand coordinated in a κ¹:κ¹:η¹-fashion via both the oxygen atoms and ortho-carbon atom of one of the phenyl rings. Compound 3 consists of an unchanged chelating dppn ligand and a terminal Cl ligand. Treatment of [Mn₂(CO)₈(MeCN)₂] with a slight excess of dppn in refluxing toluene at 72 °C, gave the previously reported [Mn₂(CO)₈(μ-PPh₂)₂] (4), formed by cleavage of C-P bonds, and the new compound fac-[MnCl(CO)₃(κ²-PPh₂C₁₀H₆PPh₂)] (5), which has an unaltered chelating dppn and a terminal Cl ligand. In sharp contrast, reaction of [Mn₂(CO)₈(MeCN)₂] with slight excess of dppn at room temperature yielded the dimanganese [Mn₂(CO)₉{κ¹-PPh₂(C₁₀H₇)}] (6) in which the diphenylnaphthylphosphine ligand, formed by facile cleavage of one of the P-C bonds, is axially coordinated to one Mn atom. Compound 6 was also obtained from the reaction of [Mn₂(CO)₉(MeCN)] with dppn at room temperature. The XRD structures of complexes 1-3, 5, 6 are reported.     

A Review Featuring Fabrication,Properties and Applications of Carbon Nanotubes (CNTs) Reinforced Polymer and Epoxy Nanocomposites

Carbon nanotubes (CNTs) have long been recognized as the stiffest and strongest man-made material known to date.In addition,their high electrical conductivity has roused interest in the areas of electrical appliances and communication related applications.However,due to their miniature size,the excellent properties of these nanostructures can only be exploited if they are homogeneously embedded into light-weight matrices as those offered by a whole series of engineering polymers.In order to enhance their chemical affinity to engineering polymer matrices,chemical modification of the graphitic sidewalls and tips is necessary.The mechanical and electrical properties to date of a whole range of nanocomposites of various carbon nanotube contents are also reviewed in this attempt to facilitate progress in this emerging area.Recently,carbonaceous nano-fillers such as graphene and carbon nanotubes (CNTs) play a promising role due to their better structural and functional properties and broad range of applications in every field.Since CNTs usually form stabilized bundles due to van der Waals interactions,they are extremely difficult to disperse and align in a polymer matrix.The biggest issues in the preparation of CNTs reinforced composites reside in efficient dispersion of CNTs into a polymer matrix,the assessment of the dispersion,and the alignment and control of the CNTs in the matrix.An overview of various CNT functionalization methods is given.In particular,CNT functionalization using click chemistry and the preparation of CNT composites employing hyperbranched polymers are stressed as potential techniques to achieve good CNT dispersion.In addition,discussions on mechanical,thermal,electrical,electrochemical and applications ofpolymer/CNT composites are also included.     

Complexation with diol host compounds. Part 36: inclusion compounds of 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol with benzene, toluene and mesitylene

The title compound 1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol (H) forms inclusion compounds with benzene, toluene and mesitylene. H·C₆H₆ (1) and H·C₇H₈ (2) crystallize in the triclinic space group P(-1) with unit cell dimensions for 1: a = 13.001(3) ?, b = 15.284(3) ?, c = 16.744(3) ?, α = 99.26(3)°, β = 74.78(3)°, γ = 64.96(3)°, Z = 4 and for 2: a = 12.922(3) ?, b = 15.159(3) ?, c = 16.562(3) ?, α = 68.12(3)°, β = 73.99(3)°, γ = 66.00(3)°, Z = 4. The hydroxyl groups of adjacent host molecules are involved in hydrogen bonding. H·C₉H₁₂ (3) exhibits a different packing arrangement with weak hydrogen bonding between the hydroxyl hydrogen of the host and the phenyl ring of the guest. The crystal system of compound 3 is monoclinic with space group C2/c, a = 23.750(5) ?, b = 8.4746(17) ?, c = 17.760(4) ?, α = 90°, β = 123.40(3)°, γ = 90°, Z = 4. The thermal behaviour of these compounds has also been studied.     

Higher order B-spline differential quadrature rule to approximate generalized Rosenau-RLW equation

In this article, B-spline-based collocation method is employed to approximate the usual and modified Rosenau-RLW nonlinear equations. The weighted extended B-spline (WEB-spline) is used as the modified form of B-spline as the usual B-splines fail to obey the Dirichlet boundary conditions. The WEB method is more general method that allows to discretize the domain into finite number of elements not necessarily start from the boundary points of the domain. Our method omits the linearization process of the nonlinear partial differential equation (PDE). Different cases are discussed by setting the parameter p=2,3,4, and 6 that appears in Rosenau-RLW equations. The error estimation is calculated, which gives good agreement of the exact solution.     

A dialkynoyl analogue of DOPE improves gene transfer of lower-charged, cationic lipoplexes

Positively-charged gene delivery agents, such as cationic liposomes, typically prepared by mixing a cationic lipid and a neutral lipid in a 1 : 1 molar ratio, exhibit a fundamental flaw: on the one hand, the charge encourages cell uptake; on the other hand, the charge leads to aggregation in vivo with anionic serum components. We herein report a more phase-stable analogue of the zwitterionic and fusogenic lipid DOPE that allows for the reduction of the cationic lipid component of the liposome from 50 to 9 mol% with almost no apparent loss in transfection activity. This reduction in charge may induce important in vivo stability whilst still imparting high cell uptake and transgene expression.