Highly oriented tunable wrinkling in polymer bilayer films confined with a soft mold induced by water vapor

The authors report the formation of highly oriented wrinkling on the surface of the bilayer [polystyrene (PS)/poly(vinyl pyrrolidone) (PVP)] confined by a polydimethylsiloxane (PDMS) mold in a water vapor environment. When PVP is subjected to water vapor, the polymer loses its mechanical rigidity and changes to a viscous state, which leads to a dramatic change in Young's modulus. This change generates the amount of strain in the bilayer to induce the wrinkling. With a shape-controlled mold, they can get the ordered wrinkles perfectly perpendicular or leaned 45 S to the channel orientation of the mold because the orientation of the resultant force changes with the process of water diffusion which drives the surface to form the wrinkling. Additionally, they can get much smaller wrinkles than the stripe spacing of PDMS mold about one order. The wrinkle period changes with the power index of about 0.5 for various values of the multiplication product of the film thicknesses of the two layers, namely, lambda similar to (h(PS)h(PVP))(1/2).

catena-Poly[[[di-mu-acetato-kappa O-4 : O '-bis[(acetato-kappa O-2,O ')manganese(II)]]-di-mu-4,4 '-bipyridine-kappa N-4 : N '] monohydrate

The title compound, {[Mn-2(CH3CO2)(4)(C10H8N2)(2)](H2O)-H-.}(n), is a one-dimensional coordination polymer with a ladder-like structure. Two Mn-II atoms, each coordinated by a chelating acetate ligand, are bridged by two bidentate acetate ligands to form a centrosymmetric [Mn-2(CH3CO2)(4)] unit. Two 4,4'-bipyridine ligands link the [Mn-2(CH3CO2)(4)] units through Mn-N bonds to generate a molecular ladder. The water O atom lies on a crystallographic twofold rotation axis.

Synthesis and characterization of hyperbranched poly(ester-amide)s based on gallic acid and DL-2-aminobutyric acid

A novel AB(3)-type monomer was prepared from gallic acid and DL-2-aminobutyric acid, and used for the synthesis of the biocompatible hyperbranched poly(ester-amide)s by self-polycondensation. The polymers were characterized via FTIR and NMR spectroscopy and thermal analysis, and the average degree of branching of the polymers was estimated to be 0.75. The polymers with abundant acetyl end groups were found to be amorphous with lower intrinsic viscosity, better thermal stability and excellent solubility.

The influence of core-shell structured modifiers on the toughness of poly (vinyl chloride)

The core-shell structured grafted copolymer particles of polybutadiene grafted polymethyl methacrylate (PB-g-PMMA, MB) were prepared by emulsion polymerization. The MB particles were used to modify poly (vinyl chloride) (PVC) by melt blending. The mechanical properties of the PVC blends were investigated. The micro-morphology of the PVC blends was observed by scanning electron microscopy (SEM). The results indicated that the samples with the best impact strength could be obtained when the core-shell weight ratio of PB to PMMA is lower than 93:7, the mechanical properties correlated well with SEM morphologies, the addition of modifier with the ratio core to shell of 93:7 could reduce the domain size of the dispersed phase. Furthermore, the compatibility and properties of the blends were greatly enhanced and improved. The modifier particles could be well dispersed in the PVC matrix.

Synthesis and characterization of hyperbranched poly(ester-amide)s from commercially available dicarboxylic acids and multihydroxyl primary amines

A new method for syntheses of hyperbranched poly(ester-amide)s from commercially available A(2) and CBx type monomers has been developed on the basis of a series of model reactions. The aliphatic and semiaromatic hyperbranched poly(ester-amide)s with multihydroxyl end groups are prepared by in situ thermal polycondensation of intermediates obtained from dicarboxylic acids (A(2)) and multihydroxyl primary amines (CBx) in N,N-dimethylformamide. Analyses of FTIR, H-1 NMR, and C-13 NMR spectra revealed the structures of the polymers obtained. The MALDI-TOF MS of the polymers indicated that cyclization side reactions occurred during polymerization. The hyperbranched poly(ester-amide) s contain configurational isomers observed by C-13 and DEPT C-13 NMR spectroscopy. The DBs of the polymers were determined to be 0.38-0.62 by H-1 NMR or quantitive C-13 NMR and DEPT 135 spectra. These polymers exhibit moderate molecular weights, with broad distributions determined by size exclusion chromatography ( SEC), and possess excellent solubility in a variety of solvents such as N, N- dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, and ethanol, and display glass-transition temperatures (T(g)s) between -2.3 and 53.2 degrees C, determined by DSC measurements.

Electrogenerated chemiluminescence biosensor based on Ru(bpy)(3)(2+) and dehydrogenase immobilized in sol-gel/chitosan/poly(sodium 4-styrene sulfonate) composite material

A new electrogenerated chemiluminescence biosensor was fabricated by immobilizing ECL reagent Ru(bPY)(3)(2+) and alcohol dehydrogenase in sol-gel/chitosan/poly(sodium 4-styrene sulfonate) (PSS) organically modified composite material. The component PSS was used to immobilize ECL reagent Ru(bpy)(3)(2+) by ion-exchange, while the addition of chitosan was to prevent the cracking of conventional sol-gel-derived glasses and provide biocompatible microenvironment for alcohol dehydrogenase. Such biosensor combined enzymatic selectivity with the sensitivity of ECL detection for quantification of enzyme substrate and it was much simpler than previous double-layer design. The detection limit was 9.3 x 10(-6) M for alcohol (S/N = 3) with a linear range from 2.79 x 10(-5) to 5.78 x 10(-2) M. With ECL detection, the biosensor exhibited wide linear range, high sensitivity and good stability.

Hydrazide-functionalized hollow porous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) spheres for immobilization of enzyme

Hollow porous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate)(HEMA-co-EDMA) spheres were prepared by emulsifier-free emulsion polymerization, swelling, seed emulsion polymerization and extraction. Then the spheres activated with 2,4,6-trichloro-1,3,5-triazine were functioned with adipohydrazide (AH). After periodate oxidation of its carbohydrate moieties, horseradish peroxidase was immobilized on the hydrazide-functionalized hollow porous poly(HEMA-co-EDMA) spheres. The amount of immobilized enzyme was up to 43.4 mu g of enzyme/g of support. Moreover, the immobilized horseradish peroxidase exhibited high activity and good stability.

Poly[di-mu(3)-chloro-mu(2)-trans-1,2-di-4-pyridylethylene-dicopper(I)]: a two-dimensional organic-inorganic hybrid constructed from linear CuCl clusters and bridging ligands

The structure of the title compound, [Cu2Cl2(C12H10N2)](n), contains infinite CuCl staircase-like chains, which lie about inversion centres. The trans-1,2-di-4-pyrid-ylethyl-ene mol-ecules also lie about inversion centres and connect the CuCl chains through Cu-N coordination bonds into a two-dimensional organic-inorganic hybrid network. The planar sheets are stacked along the c axis and associated through weak C-H center dot center dot center dot Cl inter-actions. The results show a reliable structural motif with controllable separation of the CuCl chains by variation of the length of the ligand.

catena-Poly[[[di-mu-acetato-kappa O-4 : O '-bis[(acetato-kappa O-2,O ')manganese(II)]]-di-mu-4,4 '-bipyridine-kappa N-4 : N '] monohydrate]

The title compound, {[Mn-2(CH3CO2)(4)(C10H8N2)(2)](H2O)-H-.}(n), is a one-dimensional coordination polymer with a ladder-like structure. Two Mn-II atoms, each coordinated by a chelating acetate ligand, are bridged by two bidentate acetate ligands to form a centrosymmetric [Mn-2(CH3CO2)(4)] unit. Two 4,4'-bipyridine ligands link the [Mn-2(CH3CO2)(4)] units through Mn-N bonds to generate a molecular ladder. The water O atom lies on a crystallographic twofold rotation axis.

catena-Poly[[[2-(2-furyl)-1H-imidazo[4,5-f][1,10]phenanthroline]zinc(II)]-mu-benzene-1,2-dicarboxylato]

In the title compound, [Zn(C8H4O4)(C17H10N4O)](n), the Zn-II atom is five-coordinated by two N atoms from the phenanthro-line-derived ligand and three O atoms from one bidentate and one monodentate benzene-1,2-dicarboxylate (1,2-BDC) dianions in a distorted trigonal-bipyramidal geometry. The Zn-II atoms are bridged by the 1,2-BDC ligands to form a single-chain structure. Neighboring chains interact through pi-pi interactions, leading to a two-dimensional network.

Layer-by-layer multilayer films self-assembled from a rare-earth-containing poly-oxometalate Na-9[Eu(W5O18)(2)] and poly (allylamine hydrochloride) and their photoluminescent properties

Ultrathin multilayer films of a rare-earth-containing polyoxometalate Na-9[Eu(W5O18)(2)] (EW) and Poly (allyamine hydrochloride) (PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solutions. The fabrication process of the EW/PAH multilayer films was followed by UV-vis spectroscopy and ellipsometry, which show that the deposition process is linear and highly reproducible from layer to layer. An average EW/PAH bilayer thickness of ca. 2.1 nm was determine,by ellipsometry. In addition, the scanning electron microscopy (SEM) image of the EW/PAH film indicates that the film sufface is relatively uniform and smooth. The photoluminescent properties of these films were also investigated by fluoresence spectroscopy.

Aromatic poly(ester imide)s and poly(amide imide)s having 1,1 '-binaphthyl-2,2 '-diyls in the main chain

Full Paper: Two new 1,1'-binaphthyl-2,2'-diyl-based dianhydrides, i.e., 2,2'-bis(3,4-dicarboxybenzamido)-1,1'-binaphthyl dianhydride (BNDADA) and 2,2'-bis(3,4-dicarboxybenzoyloxy)-1,1'-binaphthyl dianhydride (BNDEDA), were synthesized and polymerized with various aromatic diamines to afford polyimides through the traditional two-step method. The polyimides with inherent viscosities ranging from 0.27 to 0.70 dl . g(-1) showed excellent solubilities in polar solvents such as DMAc, DMSO and NMP etc., except of the poly(ester imide) prepared from BNDEDA and benzidine. Poly(ester imide)s based on BNDEDA can also be readily dissolved in weakly polar solvents such as THF, CH2Cl2 and CHCl3. The glass transition temperatures of these polyimides are in the range of 210-310 degrees C; the 5% weight loss temperatures are in the range of 390-465 degrees C in nitrogen and 384-447 degrees c in air. These polymers from light yellow, tough films that were transparent above 365 nm. The effects of different flexible units attached in the 2- and 2'-positions, i.e., amide, ester and ether, on the properties of the polyimides obtained are discussed.

Influence of intermolecular entanglements on the glass transition and structural relaxation behaviors of macromolecules. 2. Polystyrene and phenolphthalein poly(ether sulfone)

The effect of entanglements on the glass transition and structural relaxation behaviors has been studied for polystyrene (PS) and phenolphthalein poly(ether sulfone) (PES-C) samples by fast evaporation of the solution of concentrations varying from above the overlapping concentration to far below it, and compared to the results we have studied previously in PC. It has been found that for all the polymers we have studied, in the concentrated solution region, the T-g of the samples obtained from solution are independent of the change of concentration and are very close to that of normal bulk samples, whereas in the dilute solution region the T-g of the samples decrease with the logarithm of decreasing concentration. The critical concentrations that divide the two distinct regions for the three polymers are 0.9% g/mL for PC, 0.1% g/mL for PS, and 1% g/mL for PES-C. The decrease of T-g of the samples is interpreted by the decrease of intermolecular entanglements as the isolation of polymer chains, and the entanglement of polymer chains restrained the mobility of the segments. The structural relaxation behavior of the polymers is also found to be different from that of normal bulk samples. The enthalpies of single-chain samples are lower than that of the bulk ones, which correspond to the lower glass transition temperature; the peaks are lower and broader, and the relaxed enthalpy is much lower as compared to that of bulk samples. In the three polymers we have studied, the influence of change of entanglements on both the decrease in glass transition temperature and relaxed enthalpy is the most significant for PS and the least for PES-C. It is indicated that the interactions in the flexible polymers are weak; thus, the restraint of the entanglements on the mobility of the segments plays a more important role in the flexible polymers, and the change of entanglement in the flexible polymers has a more significant influence on the physical properties.

Voltammetric study of the sodium ion transfer across micro-water/1,2-dichloroethane interface facilitated by terminal-vinyl liquid crystal crown ether

Sodium ion transfer across micro-water/1,2-dichloroethane (DCE) interface facilitated by a novel ionophore, terminal-vinyl liquid crystal crown ether (LCCE) was studied by cyclic voltammetry. LCCEs have potential applications because of their physicochemical properties and the utilization of crown ethers as selective ionophoric units in other functionalized compounds are interesting. Host-guest-type behavior for such compounds in the liquid-crystalline state is studied. The experimental results suggest that the transfer of the sodium ion facilitated by LCCE was controlled by diffusion of LCCE from bulk solution of DCE to the interface. The diffusion coefficient of LCCE in DCE was calculated to be equal to (3.62 +/- 0.20) x 10(-6) cm(2)/s. Steady-state voltammograms are due to sodium ion transfer facilitated by the formation of 1: 1 metal (M)-LCCE complex at the interface and the mechanism tends to be transfer by interfacial complexation or dissociation (TIC or TID). The stability constant of the complex formed was determined to be log beta(o) = 5.5 in DCE phase. The influence of parameters such as concentration of sodium ion and concentration of LCCE on the sodium ion transfer was investigated.

Preparation of poly (styrene-co-4-vinyl pyridine) /silica nanoscale hybrids supported cyclopentadienyltitanium trichloride (CpTiCl3) catalyst and styrene polymerization

To obtain a novel support with practical value for metallocene catalyst (eta -C5H5)TiCl3 (CpTiCl3), poly (styrene-co-4-vinylpyridine) /SiO2 nanoscale hybrid material (SrP/SiO2) was firstly produced as support. After pretreatment by methylaluminoxane (MAO), the hybrid materials reacted with CpTiCl3. The results from SAXS, SEM and TEM indicated the morphology and structure of organic/inorganic hybrid materials, and the size of inorganic particle in hybrid was nanoscale. The results from IR and XPS showed that there were two possible cationic active species in the hybrid-supported catalyst, the polymerization results of styrene proved this possibility.