Synthesis, properties, and gas permeation performance of cardo poly(arylene ether sulfone)s containing phthalimide side groups

Novel bisphenol monomers (1a-d) containing phthalimide groups were synthesized by the reaction of phenolphthalein with ammonia, methylamine, aniline, and 4-tert-butylanilne, respectively. A series of cardo poly (arylene ether sulfone)s was synthesized via aromatic nucleophilic substitution of 1a-d with dichlorodiphenylsulfone, and characterized in terms of thermal, mechanical and gas transport properties to H-2, O-2, N-2, and CO2. The polymers showed high glass transition temperature in the range 230-296 degrees C, good solubility in polar solvents as well as excellent thermal stability with 5% weight loss above 410 degrees C. The most permeable membrane studied showed permeability coefficients of 1.78 barrers to O-2 and 13.80 barrers to CO2, with ideal selectivity. factors of 4.24 for O-2/N-2 pair and 28.75 for CO2/CH4 pair. Furthermore, the structure-property relationship among these cardo poly(arylene ether sulfone)s had been discussed on solubility, thermal stability, mechanical, and gas permeation properties. The results indicated that introducing 4-tert-butylphenyl group improved the gas permeability of polymers evidently.

Synthesis and characterization of soluble poly(amideimide)s bearing triethylamine sulfonate groups as gas dehumidification membrane material

A series of soluble poly(amide-imide)s (PAIs) bearing triethylammonium sulfonate groups were synthesized directly using trimellitic anhydride chloride (TMAC) polycondensation with sulfonated diamine such as 2,2'-benzidinedisulfonic acid (BDSA), 4,4'-diaminodiphenyl ether-2,2'-disulfonic acid (ODADS), and nonsulfonated diamine 4,4-diaminodiphenyl methane in the presence of triethylamine. The resulting copolymers exhibited high molecular weights (high inherent viscosity), and a combination of desirable properties such as good solubility in dipolar aprotic solvents, film-forming capability, and good mechanical properties. Wide-angle X-ray diffraction revealed that the polymers were amorphous. These copolymers showed high permeability coefficients of water vapor because of the presence of the hydrophilic triethylammonium sulfonate groups. The water vapor permeability coefficients (P-w) and permselectivity coefficients of water vapor to nitrogen and methane [alpha(H2O/N-2) and (alpha(H2O/CH4)] Of the films increased with increasing the amount of the triethylammonium sulfonated groups.

Nonvolatile memory devices based on gold nanoparticle and poly (N-Vinylcarbazole) composite

A rewritable polymer memory device based on gold nanoparticle doped poly (N-vinylcarbazole) (PVK), which can be easily fabricated by simple spin coating, has been described. An electrical bistable phenomenon is observed in the current-voltage characteristics of this device, and it is found that the electrical bistability is repeatable by proper writing voltage and erasing voltage. The unique behavior of the devices provides an interesting approach such that doping nanoparticles in polymer can be used to realize high performance nanovolatile polymer memory devices.

Tuning the energy level and photophysical and electroluminescent properties of heavy metal complexes by controlling the ligation of the metal with the carbon of the carbazole unit

Four novel Ir-III and Pt-II complexes with cyclometalated ligands bearing a carbazole framework are prepared and characterized by elemental analysis, NMR spectroscopy, and mass spectrometry. Single-crystal X-ray diffraction studies of complexes 1, 3, and 4 reveal that the 3- or 2-position C atom of the carbazole unit coordinates to the metal center. The difference in the ligation position results in significant shifts in the emission spectra with the changes in wavelength being 84 nm for the Ir complexes and 63 nm for the Pt complexes. The electrochemical behavior and photophysical properties of the complexes are investigated, and correlate well with the results of density functional theory (DFT) calculations. Electroluminescent devices with a configuration of ITO/NPB/CBP:dopant/BCP/AlQ(3)/LiF/Al can attain very high efficiencies.

Preparation and physical properties of enhanced radiation induced crosslinking of ethylene-vinyl alcohol copolymer (EVOH)

Preparation and physical properties of ethylene-vinyl alcohol copolymer (EVOH) crosslinked by enhanced radiation have been studied through various methods. It was found that the most effective agent for irradiation-crosslinking was triallyl isocyanurate (TAIC) among four kinds of polyfunctional monomers. Gel content (65.6%) was formed for EVOH-44 (content of ethylene is 44 mol%) at 200 kGy with 5% TAIC, but for EVOH-32 (content of ethylene is 32 mol%), only 37.4% gel content was formed under the same conditions. This result showed that the more the content of ethylene units comprised in EVOH, the easier the chemical bonds could be formed between different molecular chains. Tensile strength and elastic modulus increased after crosslinking at high test temperature and elongation at break decreased at the same time. Hygroscopicity of EVOH showed noticeable decrease after enhancement radiation-crosslinking.

Study on the lifetime of M-intermediate of bacteriorhodopsin film chemically modified with CeO2 nanoparticles

The characteristics of intermediates of bacteriorhodopsin (bR) can be verified by chemical modification of its surroundings. CeO2 nanoparticles, which were obtained using water-in-oil (W/O) microemulsion and calcined at various temperatures, were used as chemical additive for the modification of bR. X-ray diffraction (XRD) shows that the mean particle sizes for the samples calcined at 500 and 800 degrees C are approximately 10 and 30 nm, respectively. We prepared CeO2 nanoparticle modified poly(vinyl alcohol) (bR-PVA) films with an optical density of about 1.5 at the ground state. It is observed that the lifetime of the Wintermediate for the modified films is prolonged compared with that of the unmodified ones, and the lifetime increases with decreasing particle size. A probable mechanism, which is likely to involve effective molecular interactions between the CeO2 nanoparticles and the bR molecules, is discussed. The hydroxyl groups, which might arise from the interaction between the nanoparticles and the surrounding water molecules, help to lower the ability of the Schiff base of uptaking protons in the Wintermediate. The results indicate that controlling the interactions between biomolecules and various nanomaterials would enlarge the functionality and the range of the application of nanoparticles.

Preparation of CeO2-ZrO2 ceramic fibers by electrospinning

Electrospinning was employed to fabricate polymer-ceramic composite fibers from solutions containing poly(vinyl pyrrolidone) (PVP), Ce(NO3)(3)(.)6H(2)O and ZrOCl2-8H(2)O. Upon firing the composite fibers at 1000 degrees C, Ce(0.67)Zr(0.33)O(2)fibers with diameters ranging from 0.4 to 2 mu m were synthesized. These fibers exhibit strong resistance to sintering. They still have specific surface area around 11.8 m(2)/g after being heated at 1000 degrees C for 6 h.

Electron-beam irradiation on poly(propylene carbonate) in the presence of polyfunctional monomers

Poly(propylene carbonate) (PPC) showed predominantly degradation under electron-beam irradiation, accompanied by deterioration of its mechanical performance due to sharp decrease of the molecular weight. Crosslinked PPC was prepared by addition of polyfunctional monomer (PFM) to enhance the mechanical performance of PPC. When 8 wt% of PFM like triallyl isocyanurate (TAIL) was added, crosslinked PPC with a gel fraction of 60.7% was prepared at 50 kGy irradiation dose, which showed a tensile strength at 20 degrees C of 45.5 MPa, whereas it was only 38.5 MPa for pure PPC. The onset degradation temperature (T-i) and glass transition temperature (T-g) of this crosslinked PPC was 246 degrees C and 45 degrees C, respectively, a significant increase related to pure PPC of 211 degrees C and 36 C. Therefore, thermal and mechanical performances of PPC could be improved via electron-beam irradiation in the presence of suitable PFM.

An investigation on the dispersion of montmorillonite (MMT) primary particles in PP matrix

A novel path of preparing PP/o-MMT nanocomposites, which pay attention to the breaking up of MMT original agglomerates and dispersing of its primary particles, rather than the intercalation or exfoliation degree of o-MMT, was reported. The method of predispersing the o-MMT particles into a polar poly(vinyl alcohol) (PVA) matrix and then melt blending the pre-treated PVA/o-MMT hybrids with PP was studied. 3-isopropenyl-alpha,alpha-dimethylbenzene-isocyanate (TMI) was used as a modifier of PVA to improve the compatibility between PVA and PP matrix. Pre-disperse o-MMT with TMI modified PVA was proved to be an effective way to get a composite with fine o-MMT particles dispersion. But the method, which is pre-dispersing o-MMT with non modified PVA and then using TMI to modify such PVA/o-MMT hybrid, would largely reduce the reaction degree between TMI and PVA because of the relatively lower reaction temperature. Although the latter method also can obtain finer dispersion composites than that with using PP-g-MAH as compatibilizer, the relatively higher degradation degree of PP matrix in this method will limit the use of this nanocomposite.

A novel approach to synthesis of functional CPVC and CPE or graft copolymers - in situ chlorinating graft

A new process of graft copolymerization of poly(vinyl chloride) (PVC) and polyethylene (PE) with other monomers was developed. The grafted chlorinated poly(vinyl chloride) (CPVC) and chlorinated polyethylene (CPE) were synthesized by in situ chlorinating graft copolymerization (ISCGC) and were characterized. Convincing evidence for grafting and the structure of graft copolymers was obtained using FT-IR, H-1-NMR, gel permeation chromatography (GPC), and the vulcanized curves. Their mechanical properties were also measured. The results show that the products have different molecular structure from those prepared by other conventional graft processes. Their graft chains are short, being highly branched and chlorinated. The graft copolymers have no crosslinking structure. The unique molecular structure will make the materials equipped with special properties.

Electrostatic assembly of polyaniline and platinum-poly(amidoamine) dendrimers hybrid nanocomposite multilayer, and its electrocatalysis towards CO and O-2

The electrostatic layer-by-layer assembly method was successfully used in a multilayer buildup of polyaniline (PANT) and platinum nanocrystals encapsulated in the carboxyl-terminated poly(amidoamine) dendrimers (generation 4.5 G4.5COOH) (Pt-G4.5COOH NPs) on solid substrates. Multilayer growth was monitored by ultraviolet-visible (UV-vis) absorption spectroscopy. The AFM observation revealed a molecularly smooth (PANI/Pt-G4.5COOH NPs) multilayer film which is rougher and thicker than the multilayer of PANT and G4.5COOH (G4.5COOH/PANI)(m). The PANI/Pt-G4.5COOH NPs multilayers show a fast surface-confined electron-exchange process at the Au electrode in an acid solution, and remains stable, reversible and electroactive, even in neutral solution. Furthermore, the multilayers show a strong elect rocatalytic response towards CO oxidation and O-2 reduction, and the catalytic capability can be easily tuned by the control of multilayer thickness.

Surface morphology evolution of poly (styrene-block-4-vinylpyridine) (PS-b-P4VP)(H+) and poly(methyl methacrylate)-dibenzo-18-crown-6-poly(methyl methacrylate) (PMCMA) supramolecular film

Well-ordered nanostructured polymeric supramolecular thin films were fabricated from the supramolecular assembly of poly(styrene-block-4-vinylpyridine) (PS-b-P4VP)(H+) and poly(methyl methacrylate)-dibenzo-18-crown-6-poly(methyl methacrylate) (PMCMA). A depression Of cylindrical nanodomains was formed by the block of P4VP(H+) and PMCMA associates surrounded by PS. The repulsive force aroused from the incompatibility between the block of P4VP(H+) and PMCMA was varied through changing the molecule weight (M-w) of PMCMA, the volume fraction of the block of P4VP(H+), and annealing the film at high temperature. Increasing the repulsive force led to a change of overall morphology from ordered nanoporous to featureless structures. The effects of solvent nature and evaporation rate on the film morphology were also investigated. Further evolution of surface morphologies from nanoporous to featureless to nanoporous structures was observed upon exposure to carbon bisulfide vapors for different treatment periods. The wettability of the film surface was changed from hydrophilicity to hydrophobicity due to the changes of the film surface microscopic composition.

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).

Study of hydrogen-bonded blend of polylactide with biodegradable hyperbranched poly(ester amide)

Polylactide (PLA) was melt blended with a biodegradable hyperbranched poly(ester amide) (HBP) to enhance its flexibility and toughness without sacrificing comprehensive performance. The advantage of using HBP was due to its unique spherical shape, low melt viscosity, and abundant functional end groups together with its easy access. Rheological measurement showed that blending PLA with as little as 2.5% HBP resulted in a 40% reduction of melt viscosity. The glass transition temperature (T-g) of PLA in the blends decreased slightly with the increase of HBP content, indicating partial miscibility which resulted from intermolecular interactions via H-bonding. The H-bonding involving CO of PLA with OH and NH of HBP was evidenced by FTIR analysis for the first time. The HBP component, as a heterogeneous nucleating agent, accelerated the crystallization rate of PLA. Remarkably, with the increase of HBP content, the elongation at break of PLA blends dramatically increased without severe loss in tensile strength, even the tensile strength increased within 10% content of HBP. The stress-strain curves and the SEM photos of impact-fractured surface showed the material changed from brittle to ductile failure with the addition of HBP. Reasonable interfacial adhesion via H-bonding and finely dispersed particulate structure of HBP in PLA were proposed to be responsible for the improved mechanical properties.

Morphology of electrodeposited poly(3,4-ethylenedioxythiophene)/poly(4-styrene sulfonate) films

Poly(4-styrene sulfonate)-doped poly(3,4-ethylenedioxythiophene) (PEDOT/PSS) films with ring-, arrow-, and bubble-like microstructures have been electrochemically generated simply by a one-step cyclic voltammetry in an aqueous media. Influences of applied potentials and surfactant/dopant-PSS on morphology of the resulting film were investigated, and a gas bubble template mechanism has been proposed. The result confirmed a well-doping of PSS in the PEDOT film. Electrochemical property and conductivity of the micro-structured PEDOT/PSS film were investigated further. Similar preparation with potential applications in fabrication of microdevices and micro-sensors can be extended to other micro-structured conducting polymers.