Suppress voltage decay of lithium-rich materials by coating layers with different crystalline states

Li-rich oxides are considered as the most commercial potential cathode materials due to the high theo-retical specific discharge capacity.Here,ZrO2 in different...     

Synthesis of copolymer-stabilized silver nanoparticles for coating materials

Silver ions being less toxic than silver nanoparticles, a more safe material can be obtained to be used as antimicrobial coating. This can be achieved by using thiol chemistry and covalently attach the silver nanoparticles in the coating. Our aim is to produce a coating having antimicrobial properties of silver ions but with the silver nanoparticles firmly attached in the coating. Here, we present a way to produce silver nanoparticles that can be used as a component in a coating or as such to produce an antimicrobial coating. The silver nanoparticles presented here are stabilized by a copolymer (poly(butyl acrylate–methyl methacrylate)) that is soft and has well-known good film-producing properties. The reversible addition-fragmentation chain transfer radical polymerization technique used to prepare the polymers provides conveniently a thiol group for effective binding of the silver nanoparticles to the polymers and thus to the coating.     

Modification of new polymer materials based on aminostyrene by irradiation

The ultra-violet (UV) irradiation induced modification of the mechanical and optical properties of several polymer composites containing 4-aminostyrene and glycidyl methacrylate and their dependences on radiation dose, structure and ageing have been investigated. The nano- and microindentation techniques were used for determination of the mechanical parameters of as-grown and irradiated materials. The light-induced structural changes result in an increase of the hardness and elastic modulus of the polymer layers up to five and three times, respectively. It is also shown that the influence of polymer structure is significant. The conditions for improvement, degradation and stabilization of physical properties by UV irradiation were established. Load and depth sensing indentation has proved to be a powerful tool for an accurate estimation of mechanical properties of cross-linking polymer compositions. Variable-energy positron annihilation spectroscopy (slow-positron beam technique) was developed to measure defect depth profiles in the near-surface region. The increase of S-parameter with the increase of nano-hardness and elastic modulus has been determined for these materials.     

Characteristics of interfacial layers of polymer composite materials

Design diagrams are given based on which engineering models are developed allowing one to calculate the characteristics of interfacial layers of polymer composite materials are given. Theoretical and experimental investigations of interfacial layer thicknesses are comparatively evaluated.     

Formation of composite membranes containing hydrophobic polymer layers by electron-beam sputter deposition

The chemical structure and the contact and morphological properties of composite membranes prepared by electron-beam sputter deposition of a polytetrafluoroethylene layer on the surface of track-etched polypropylene membrane have been studied. It has been found that the application of such layers results in bilayer composite membranes with both the layers having hydrophobic properties. It has been shown that an increase in the thickness of the deposited polytetrafluoroethylene layer leads to development of its roughness, resulting in the formation of a polymer with superhydrophobic properties on the surface of the initial membrane.     

Permeability of polymer materials to compounds containing radionuclides

The permeability of rubber and PE gloves, PE bags and strippable PVC paint to HTO, Na¹²⁵I, H₂ ³⁵SO₄, H₃ ³²PO₄,¹⁴¹CeCl₃,⁸⁹SrCl₂, and,¹³⁷CsCl in aqueous solution was tested. All materials were permeable to HTO and Na¹²⁵I. Whereas rubber gloves were permeable the other materials were impermeable to H₂ ³⁵SO₄. The remaining radioactive compounds showed no penetration. The diffusion coefficients of the penetrating compounds were calculated on the basis of Fick's First Law for the respective materials. The permeability to Na¹²⁵I and HTO decreases in the order rubber, PVC paint, and PE. Penetration increases in the order H₂ ³⁵SO₄, Na¹²⁵I, and HTO.     

Sonochemical coating of paper by microbiocidal silver nanoparticles

Colloidal silver has gained wide acceptance as an antimicrobial agent, and various substrates coated with nanosilver such as fabrics, plastics, and metal have been shown to develop antimicrobial properties. Here, a simple method to develop coating of colloidal silver on paper using ultrasonic radiation is presented, and the coatings are characterized using X-ray diffraction (XRD), high resolution scanning electron microscope (HRSEM), and thermogravimetry (TGA) measurements. Depending on the variables such as precursor concentrations and ultrasonication time, uniform coatings ranging from 90 to 150 nm in thickness have been achieved. Focused ion beam (FIB) cross section imaging measurements revealed that silver nanoparticles penetrated the paper surface to a depth of more than 1 μm, resulting in highly stable coatings. The coated paper demonstrated antibacterial activity against E. coli and S. aureus, suggesting its potential application as a food packing material for longer shelf life.     

Fabrication of interdigitated micropatterns of self-assembled polymer nanofilms containing cell-adhesive materials

Micropatterns of different biomaterials with micro- and nanoscale features and defined spatial arrangement on a single substrate are useful tools for studying cellular-level interactions, and recent reports have highlighted the strong influence of scaffold compliance in determining cell behavior. In this paper, a simple yet versatile and precise patterning technique for the fabrication of interdigitated micropatterns of nanocomposite multilayer coatings on a single substrate is demonstrated through a combination of lithography and layer-by-layer (LbL) assembly processes, termed polymer surface micromachining (PSM). The first nanofilm pattern is constructed using lithography, followed by LbL multilayer assembly and lift-off, and the process is repeated with optical alignment to obtain interdigitated patterns on the same substrate. Thus, the method is analogous to surface micromachining, except that the deposition materials are polymers and biological materials that are used to produce multilayer nanocomposite structures. A key feature of the multilayers is the capability to tune properties such as stiffness by appropriate selection of materials, deposition conditions, and postdeposition treatments. Two- and four-component systems on glass coverslips are presented to demonstrate the versatility of the approach to construct precisely defined, homogeneous nanofilm patterns. In addition, an example of a complex system used as a testbed for in vitro cell adhesion and growth is provided: micropatterns of poly(sodium 4-styrenesulfonate)/poly-L-lysine hydrobromide (PSS/PLL) and secreted phospholipase A(2)/poly(ethyleneimine) (sPLA(2)/PEI) multilayers. The interdigitated square nanofilm array patterns were obtained on a single coverslip with poly(diallyldimethylammonium chloride) (PDDA) as a cell-repellent background. Cell culture experiments show that cortical neurons respond and bind specifically to the sPLA(2) micropatterns in competition with PLL micropatterns. The fabrication and the initial biological results on the nanofilm micropatterns support the usefulness of this technique for use in studies aimed at elucidating important biological structure-function relationships, but the applicability of the fabrication method is much broader and may impact electronics, photonics, and chemical microsystems.     

Modification of diamond single crystals by chromium ion implantation with sacrificial layers

Single-crystal diamond surfaces were implanted with chromium ions. Ion energies chosen were 120 and 180 keV. Ion doses of 1x10(17) cm(-2) were applied at a substrate temperature of 750 degrees C. Reduced lattice damage could be obtained by deposition of a titanium sacrificial layer with a thickness of 10 and 50 nm before implantation. Depth profiles of the elemental binding states were taken by photoelectron spectroscopy. The effect of the sacrificial layer thickness on diamond lattice damage was investigated by infrared spectroscopy.     

Controlling ion motion in polymer light-emitting diodes containing conjugated polyelectrolyte electron injection layers

The properties and function of an anionic conjugated polyelectrolyte (CPE)-containing ion-conducting polyethylene oxide pendant (PF(PEO)CO(2)Na) as electron injection layers (EILs) in polymer light-emitting diodes (PLEDs) are investigated. A primary goal was to design a CPE structure that would enable acceleration of the device temporal response through facilitation of ion motion. Pristine PLEDs containing PF(PEO)CO(2)Na exhibit luminance response times on the order of tenths of seconds. This delay is attributed to the formation of ordered structures within the CPE film, as observed by atomic force microscopy. Complementary evidence is provided by electron transport measurements. The ordered structures are believed to slow ion migration within the CPE EIL and hence result in a longer temporal response time. It is possible to accelerate the response by a combination of thermal and voltage treatments that "lock" ions within the interfaces adjacent to PF(PEO)CO(2)Na. PLED devices with luminance response times of microseconds, a 10(5) fold enhancement, can therefore be achieved. Faster luminance response time opens up the application of PLEDs with CPE layers in display technologies.     

PMMA colloid particles armored by clay layers with PDMAEMA polymer brushes

Poly[2‐(dimethylamino) ethyl methacrylate] (PDMAEMA) brushes on the surfaces of clay layers were prepared by in situ free‐radical polymerization. Poly (methyl methacrylate) (PMMA) colloid particles stabilized and initiated by clay layers with PDMAEMA polymer brushes were prepared by Pickering emulsion polymerization. Transmission electron microscopy was used to characterize the structure and morphology of the colloid particles. The X‐ray diffraction (XRD) results indicated that the intercalated structures of the clay layers were almost destroyed in Pickering emulsion polymerization, and clay layers with exfoliated structures were created. The surface of the colloid particles was analyzed by using X‐ray photoelectron spectroscopy (XPS). The XPS results provide direct evidence that the clay layers with PDMAEMA chains cover the PMMA colloid particles. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 2632–2639, 2008     

Modification of styrene polymer with organosilicon groups

The homopolymer of 4‐chloromethylstyrene (P1) and its copolymers with styrene (in various mole ratios) were synthesized by bulk and solution free radical polymerizations, respectively, at 70 ± 1°C using α,α′‐azobis(isobutyronitrile) as an initiator. Lithiation of these soluble polymers in THF at −78°C was done and reacted with electrophiles such as tert‐BuMe₂Si, Et₃Si, and Me₃SiCH₂ in the presence of 4,4′‐di‐tert‐butylbiphenyl (DTBB) as a catalyst to produce modified polystyrene. In the other way, trimethylsilylmethyl lithium substitute as a nucleophile was covalently linked to the homopolymer and copolymer. The polymers were characterized by IR, ¹H NMR, ¹³C NMR, differential scanning calorimetry (DSC), and gel permeation chromatography. DSC showed that incorporation of silyl substitute in the side chains of homopolymer and copolymers increases the rigidity of the polymers and, subsequently, their glass transition temperature. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:414–420, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20314     

Synthesis, structure and luminescent property of a 2D polymer containing silver ions

Silver(I) complex with 4,5-dicarboxyimidazole (H₃dcbi) has been synthesized by hydrothermal method and proven to be a novel 2D coordination polymer [Ag(H₂dcbi)]_n (1), which crystallized in monoclinic crystal system and space group of P2(1)/c. Each Ag(I) ion is coordinated to three O atoms and one N atom, which completes the trigonal pyramidal geometry of Ag(I) ion. Solid-state fluorescent emission spectra of 1 were investigated.     

Interaction of surfactant with antistatic polymer thin layers

Thin layers made from three kinds of hydrophilic polymer were coated onto poly(ethylene terephthalate)(PET) fibers to study the interaction of an anionic surfactant, sodiumn-dodecyl benzenesulfonate, with the polymer layers. The coated layers include a) poly(vinyl alcohol) (PVA) crosslinked with glutaraldehyde [nonionic], b) crosslinked, sulfated PVA [anionic], and c) polyethyleneimine crosslinked with poly(ethyleneglycol diglycidylether) [cationic]. All of these coatings were found to reduce the electrostatic charging of the PET cloths, indicating that they were effectively coated with the hydrophilic polymers. The PET cloth coated with the thin layers was immersed in the aqueous solution of surfactant at 40°C for different durations and the electrostatic voltage as well as the weight change were determined after drying. When the cloth coated with the nonionic or the anionic layer was brought into contact with the surfactant, neither the electrostatic voltage nor the weight of PET changed. On the contrary, immersion in the surfactant solution brought about an increase in both the electrostatic voltage and the weight for the PET coated with the cationic layer. This suggested that the surfactant molecules were bound to the cationic layer, in contrast to the nonionic and the anionic layer. It was concluded that the binding was due to ion complexing between the cationic groups in the polymeric layer and the sulfate groups in the surfactant molecules.     

Patterned colloid assembly by grafted photochromic polymer layers

Quartz surfaces and colloidal silica particles were derivatized with a poly(methyl methacrylate) copolymer containing spirobenzopyran (SP) photochromic molecules in the pendant groups at a concentration of 20 mol %. Two-photon near-IR excitation (approximately 780 nm) was then used to create chemically distinct patterns on the modified surfaces through a photochromic process of SP transformation to the zwitterionic merocyanine (MC) isomer. The derivatized colloids were approximately 10 times more likely to adsorb onto the photoswitched, MC regions. Surface coverage and adsorption kinetics have been compared to the mean-field model of irreversible monolayer adsorption.     

Optical coherence tomography image analysis of polymer surface layers in sound-absorbing fibrous composite materials

The material surface layer affecting sound absorption was identified by optical coherence tomography (OCT) image analysis. To characterise this layer, a special algorithm was developed to distinguish the polymer surface layer in thermoplastic composite materials, define its structure and thickness, and specify differences in these properties. The composite materials were obtained by thermal pressing of multilayer systems comprising viscose/polylactide and polylactide nonwoven fabrics, yielding thin polymer surface layers on the order of several hundred micrometres. The results of the measured sound absorption coefficient were analysed together with the OCT results. The use of OCT for the study of materials with specific acoustic characteristics was successfully demonstrated.     

Creation of novel polymer materials by processing with inclusion compounds

The processing of polymer materials from their inclusion compounds (ICs) formed with urea (U) and cyclodextrin (CD) hosts is described. Several examples are presented and serve to demonstrate the fabrication of unique polymer‐polymer composites and blends, including intimate blends of normally incompatible polymers, and the delivery of additives to polymers by means of embedding polymer‐ or additive‐U and CD‐ ICs into carrier polymer films and fibers, followed by coalescence of the IC guest, or by coalescence of two polymers or a polymer and an additive from their common CD‐IC crystals.     

Steric repulsion by adsorbed polymer layers studied with total internal reflection microscopy

Total internal reflection microscopy (TIRM) was applied to measure the interaction potential between charge-stabilized polystyrene latex spheres and a glass wall in dependence on the concentration of additional poly(ethylene oxide). The influence of the polymer can be described by steric repulsion between polymer layers, which are physically adsorbed onto the surfaces of the polystyrene sphere and the glass wall. The expected attractive contribution to the potential due to polymer depletion was not observed. An increase of the polymer bulk concentration is shown to strengthen the steric repulsion. At the highest polymer concentrations studied, it is possible to accurately describe the experimental data for the steric contribution to the total interaction potential with the Alexander-de Gennes model for brush repulsion.     

Chemical deposition coating onto anodized aluminum plate from anionic polymer emulsion containing sodium citrate

The chemical deposition coating from an anionic acrylic copolymer emulsion containing sodium citrate onto anodized aluminum plates was repeated. In the absence of sodium citrate, the coating thickness decreased with the number of repeated use of the emulsion bath. However, in the presence of sodium citrate or potassium sodium tartrate, it was maintained to be constant. The reason for attainment of the desirable results was discussed.Part CXL of the series Studies on Suspension and Emulsion