Studies on the preparation and properties of conductive polymers. III. Metallized polymer films by retroplating out

A novel method to prepare polymer metallized films was found by using polymer metal chelate films treated with wetted metal plates (or metal powders). The polymer metal chelate films were prepared by metal salts mixed with the polymers containing a functional group, such as poly(vinyl alcohol) (PVA), polyamide, polyacrylamide (PAAm), and polyurethane (PU). This novel method is called the retroplating-out method. Polymer metallized films exhibited low surface resistivity around 10^?1 Ω/cm² by using this novel method. The surfaces of these films were shown to be metallized by means of X-ray analysis. The conduction mechanism was verified reasonably well by using scanning electron microscope (SEM) and UV-visible absorption data.     

Single-ion conduction in UV-crosslinked films of poly(urethane-co-(alkali-metal methacrylates))

A series of crosslinked copolymers of poly(ethylene glycol-co-2,4-tolyl diisocyanate-co-(alkali-metal methacrylates)) were prepared by copolymerization of polyurethane oligomer with alkali-metal methacrylate. Cast films of these copolymers obtained by UV-crosslinked polymerization are completely amorphous and have a relatively low T_g. The films provide good mechanical properties and high ionic conductivity without additional solvent or inorganic salts. DC ionic conductivity of the films at room temperature is stable over time indicating that the copolymer is a cationic single-ion conductor. AC conductivity of these films depends mainly on the ionic radius, segmental motion of the polymer chains and local environment of the ions in the polymer matrix.     

A thermoplastic polyurethane/rare earth composite film with adjustable fluorescence colors and optimal low-temperature flexibility

In this study, a unique series of luminous polymeric rare earth (RE) composite films was produced by loading RE ions into thermoplastic polyurethane (TPU) using solution blending. Compared to RE ions, luminous polymeric RE composites had greater luminescence intensity, indicating that the introduction of polymer polyurethane as the polymer matrix was advantageous for the luminescence intensity and efficiency of RE ions, with the polymer matrix's absorbed energy being transferred to the RE ions. Furthermore, the findings of the optical transmittance, UV–visible absorption and fluorescence emission spectra suggest that TPU-RE composite films possess exceptional fluorescence luminescence properties and optical transparency. Surprisingly, the fluorescence colors of TPU-RE fluorescent films could be adjusted between red and green by varying the ratios of Eu³⁺ and Tb³⁺ in the films and can be any mixture of red and green hues. In addition, the temperature at 5% weight loss (T_5%) for the TPU-RE composite film composition reached 250 °C. In addition, pure TPU and all TPU-RE hybrid films demonstrated a glass transition temperature (T_g) of about −30 °C. Simultaneously, the tensile strength of the TPU-T₀E₁₀ film reached its maximum (43.6 MPa). Consequently, the TPU-RE composite films will be utilized as photoluminescent functional materials. © 2022 Society of Industrial Chemistry.     

Studies on the preparation and properties of conductive polymers. X. Using metal plates to prepare metallized conductive polymer films

In this article, polymer metal chelate solutions were prepared by metal salts mixed with the polymers containing functional groups such as poly(vinyl alcohol) (PVA), polyacry-lonitrile (PAN), and polyurethane (PU). These polymer metal chelate solutions were cast on to metal plates, whose oxidation potentials were greater than those of the metal of polymer metal chelate solutions. After heat treatment, the metal ions in the polymer films were reduced to metal on the surface, therefore metallized conductive polymer films were obtained. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of polyurethane/microcrystalline cellulose bionanocomposites

In this study, novel polyurethane/cellulose hybrid bionanocomposite films have successfully been prepared by dispersing microcrystalline cellulose in a polyurethane matrix. Incorporation of microcrystalline cellulose in a polyurethane matrix improved the mechanical properties significantly. The polyurethane/cellulose bionanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and transmission electron microscopy (TEM). The TEM results confirm that the nanoparticles were dispersed uniformly in polymer matrix. Additionally, thermogravimetric analysis data showed an improvement of thermal stability of novel nanocomposite films as compared to the neat polymer.     

Mechanical properties and linear infrared dichroism of thin films of polyurethane nanocomposites

Morphological, mechanical, and Fourier transform infrared dichroic investigations were performed on neat polyurethane (PU) polymer matrix and PU+CaCO₃ nanocomposite thin films to determine how the nanofiller influenced the mechanical properties. The measurements were performed on strips that were cut from the prepared films in parallel and perpendicular directions with respect to the direction of film preparation. Optical microscopy of PU and the PU+CaCO₃ nanocomposite revealed the strain‐induced transition from a continuous spherulitic morphology to a fiberlike structure. The stress–strain behavior of the neat PU and PU+CaCO₃ nanocomposite films showed significant differences at large strain regimes. The experimental results suggest that the mechanical properties were strongly related to the orientational behavior of the separated phases. The orientation of the hard and soft segments was analyzed by the orientation function calculated from the IR absorbances. A correlation between the orientations of segments, tensile properties, and hardness of the investigated polymer films was established. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and Characterization of Novel Thermoplastic Films for Removal of Heavy Metal Ions

The main objective of this study is to establish the applicability of novel thermoplastic films based on extracted gelatins from bovine (G_b) and bird (G_c) bones in addition to hide powder (HP), which blended with modified polyethylene (MPE) for the removal of heavy metal ions such as copper (II), chromium (VI), nickel (II) and zinc (II) from aqueous media. The chemical reaction between 2-oxoglutaric acid with furfural in presence of methyl amine, via Mannich reaction mechanism, resulted in chemical compound I. The chemical structure of product I was confirmed by different spectroscopic tools such as: nuclear magnetic resonance (¹³C- and ¹H-NMR) and Fourier transform infrared spectroscopy (FT-IR). The synthesized chemical product I was used as compatibilizing agent for blending G_b, G_c and Hp with MPE to obtain thermoplastic films using a polymer melting technique. The efficiency of the prepared films for absorption of different heavy metal ions from aqueous solution was investigated. The results indicated that the compatibilized films (MPE/I/HP) illustrated a maximum removal of zinc metal ions (～100%) under conditions of initial metal concentration about 240 mg/l. While, at initial metal concentration of about 150 mg/l, they exhibited excellent efficiency for removal of mixed metal ions of about 97–100% relative to the uncompatibilized ones (MPE/HP) 0%.     

Morphological and Mechanical Properties of Poly (Vinyl Alcohol) Doped with Inorganic Fillers

A number of polymer composite films using polyvinyl alcohol (PVA) as the preorganized polymer matrix were synthesized embedding different metal salts of transition elements like copper, cobalt, nickel, iron, cadmium, and zinc by a biomimetic route. The metal salts present in composites were reduced in situ to metallic form. The composites were characterized by FTIR, SEM, and EDAX. The SEM analysis confirmed the presence of nano-sized metal particles uniformly distributed in the polymer matrix. Mechanical properties were measured for various composite and PVA films. Significant improvement in some of the mechanical properties of polymer composites was realized in comparison with PVA.     

Thermal and thermomechanical behavior of amino functionalized and metal decorated MWCNTs/PMMA nanocomposite films

The homogeneous nanocomposites (NC) films of amino modified and metal decorated multiwall carbon nanotubes (MWCNTs) with polymethylmethacrylate (PMMA) were synthesized through in‐situ free radical polymerization. Silver metal nanohybrids (Ag/MWCNTs) were prepared by two strategies, that is, reduction of metal salt in presence of sodium dodecyl sulfate and in‐situ growth from AgNO₃ aqueous solution. The amino functionalization by ball milling enhanced the dispersion of MWCNT in monomer and produced a new class of radiation resistant NC. These synthesized films were characterized by FTIR, TGA, TEM, EDX, TC, DMA, and optical microscopy to ascertain their structural morphologies, thermal stability, and mechanical strength. Microscopic studies reflect the homogeneous mixing of amino functionalized and metal decorated MWCNTs in polymer matrix contributing in the enhancement of thermal stability, thermo‐mechanical strength, glass transition temperatures, and thermal conductivity of NC even at 0.25 wt% addition of modified nanofiller. The thermal stability of NC film at 0.25 wt% loading was increased around ≂50°C and the raise of thermo‐mechanical properties was observed up to 85% at 100°C in the presence of adsorbed surfactant. Thermal and thermomechanical behavior of pre and post UV/O₃ irradiated NC films has been compared with neat polymer. The results revealed that amino modified nanofiller embedded network in polymer matrix can effectively disperse the radiation and has a dramatic reinforcement effect on the nature of degradation of PMMA matrix. POLYM. COMPOS., 35:1807–1817, 2014. © 2013 Society of Plastics Engineers     

Formation of metal-polymer hybrid nanostructures during radiation-induced reduction of metal ions in poly(acrylic acid)-poly(ethylenimine) complexes

The formation of nanoparticles during the radiation-induced chemical reduction of silver ions, copper ions, and nickel ions in films based on poly(acrylic acid)-poly(ethylenimine) complexes are studied via electron microscopy. This approach allows preparation of composites containing nanoparticles that are randomly distributed in the polymer matrix and materials with a regular spatial distribution of nanoparticles across the film thickness and in subsurface layers. The structure of metal-polymer hybrid materials is dependent on the irradiation conditions, the type of reduced metal ions, and their initial content in polymer matrices. The ratio between the rate of nucleation and the rate of growth of nanoparticles in the matrices of interpolyelectrolyte complexes depends on the intensity of the absorbed dose and on the mechanisms of reduction of metal ions and formation of clusters. The IR spectroscopic studies reveal the effect of nanoparticles on the chemical structure of the polymer matrix.     

Powder synthesis from metal-organic precursors

Thermal conversion of organic polymers such as polymethylsilane [(CH₃)₂Si]_n, polymethylphenylsilane, and polysilazane or inorganic polymer such as silicimide [Si(NH)₂]_n, and thermal and hydralylic decomposition of metal alkoxides, M(OR)_n, have been employed to obtain submicron size 30–500 Å powders, continuous fibers and thin films of refractory carbides, nitrides and oxides. The high surface activity associated with these powders make possible relatively low temperature processing of the powders compact to near theoretical density and uniform fine grain size bodies. Transmission electron microscopy is used to show nucleation, growth crystallite morphology of the powders synthesized, and microstructural features observed.     

Electrodes covered with thin,permeable polymer films

Because of the recent interest in electrodes modified with thin polymer films the question of permeability of such films to electrolytes and electroactive species is discussed. Glow-discharge polymer films prepared on platinum electrodes from 4-vinylpyridine were used as model systems. They were investigated mainly with electrochemical techniques. ln particular, the analysis of the electrode impedance over a frequency range of 10–3000 Hz gave valuable information about the structure of the metal—polymer interface in presence of the electrolyte.The films prepared on the anode of the glow discharge were found to act as semi-permeable membranes. Hydrogen could be oxidized on the platinum—polymer interface of these polymer covered electrodes at rates comparable to uncovered platinum, while the films were impermeable to iron ions. The matrix prepared on the cathode was more rigid due to cross-links, and thus less permeable.The polymer matrix was more or less electroactive itself. This was probably due to quinone-type groups formed with oxygen and water after the glow-discharge polymerization process. The oxidation and reduction of these groups gave rise to a Warburg-type contribution to the electrode impedance.     

Antibacterial oil‐based polyurethane films for wound dressing applications

As an alternative to petroleum‐based polyol, hydroxyl containing material was prepared from linseed oil for polyurethane synthesis. Hexamethylene di‐isocyanate (HMDI) and/or 4, 4′‐methylene diphenyl di‐isocyanate (MDI) were used as isocyanate source. The polymerization reaction was carried out without catalyst. Polymer films were prepared by casting‐evaporation technique. The MDI/HMDI‐based polyurethane and its films had higher T_g and better thermal property than that of the HMDI‐based one because of the existence of benzene ring in the polymer chain. Static water contact angle was determined to be 74° and 77.5° for HMDI and MDI/HMDI‐based films, respectively. Water adsorption was found to be around 2.6–3.6% for both films. In vitro degradation of polyurethanes in phosphate buffered saline at 37°C was investigated by gravimetric method. Fourier transform infrared spectroscopy and scanning electron microscopy were used for confirmation of degradation on the polymer surface. The degradation rate of the HMDI‐based polyurethane film was found higher than that of the MDI/HMDI‐based film. Both the direct contact method and the MMT test were applied for determination of cytotoxicity of polymer films, and the polyurethane films investigated here was not cytotoxic. Silver‐containing films were prepared using Biocera A® as filler and were screened for their antibacterial performance against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and/or Bacillus subtilis. The films prepared with and without Biocera A® exhibited antibacterial activity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Studies on the preparation and properties of conductive polymers. IV. Novel method to prepare metallized plastics from metal chelates of polymides–imides

A new type of polyamide–imides (PAI) was synthesized by direct polycondensation. A series of polyamide–imide metal chelate films was prepared by the transition-metal salts (AgNO₃, CuCl₂, and CoCl₂) mixed with the polyamide–imides in NMP solution. These polyamide–imide metal chelate films were reduced by various reducing agents, and the reduced films exhibited low surface resistivity around 10⁰?10¹ Ω/cm². The surfaces of these conductive films were proved to be metallized by means of X-ray analysis. The metal adhered on the film was believed to be responsible for the improvement of electrical conductivity. The effects of kinds and concentrations of metal salts, kinds and concentrations of reducing agents, and reduction time on the conductivity of metallized films were investigated. The IR spectra and SEM observations of unreduced and reduced polymer chelate films were also studied.     

Preparation and Characterization of Conducting Pmma-Pani Films

Poly(methyl methacrylate) (PMMA)-polyanilin (PANI) conducting films were prepared by the diffusion+xidation method. Infrared and electronic spectra show new bands which confirm the interaction between PMMA-PAN1 and the metal cation. The microstructure of the prepared films has been investigated by an optical microscope. The results indicate that the oxidation process changed the shape and the color of the gel, which reflects the fact that the metal cation diffused through the polymer matrix. The temperature dependence of the electrical conductivity of the prepared films was studied. The results indicate that the oxidation of PMMA-PANI films by FeCl₃ leads to reduction in the resistivity of the films from 10¹³ to 10³ Ω cm (i.e., from insulator to semiconductor). The activation energy and the mechanism of the conduction were also discussed.     

Abrasion resistance of waterborne polyurethane films incorporated with PU/silica hybrids

We describe polyurethane (PU)/silica hybrids (PSHs) prepared through hydrolysis and condensation reactions of tetraethoxysilane (TEOS) with or without methyltriethoxysilane (MTES) in the presence of polyurethane dispersion, which were subsequently incorporated into waterborne polyurethane (WPU) to prepare composites. The effects of the solid mass ratio of PSHs/WPU on the particle size of composite emulsions, the dispersion of silica nanoparticles in composite films, and the hardness and abrasion resistance of the corresponding films were examined. Composite emulsions possess a nanoscale particle size when incorporated with PSHs prepared using TEOS and MTES as precursors, and are superior to those with PSHs prepared using TEOS alone. Transmission electron microscopy revealed that silica nanoparticles had a uniform distribution in the polymer matrix and agglomerates could be almost completely avoided through in situ modification of silica with Si-CH₃ groups in the polyurethane dispersion. Composite films prepared with this method exhibited a superior hardness and abrasion resistance even at a lower silica content compared with that containing unmodified silica. In particular, optical microscopy and scanning probe microscopy observations demonstrated wear behavior differences among these composite films from the macro- and nanoscale viewpoints, respectively. It is proved that abrasive wear occurs, and surface morphology studies are in accordance with the results of abrasion resistance tests.     

Fabrication of Si3N4 preforms from Si3N4 produced via CRN technique

Ceramic preforms with randomly distributed particles as reticulated porous structure which are generally used for metal infiltration as reinforcement, membranes, catalyst supports etc. Preforms are characterized by open porosity making possible their infiltration by liquid metal alloys. In this work, quartz powders using carbon black as a reducing agent were used for alpha Si₃N₄ powders synthesis through a carbothermal reduction and nitridation (CRN) process. The CRN process was carried out under nitrogen flow at 1,450 °C for 4 h. At high temperatures, carbon as reducing agent reacts with the oxygen of SiO₂, and the resulting metallic silicon compounds with nitrogen gas to obtain silicon nitride powder. The reacted powders were used to obtain reticulated ceramic by replica method. The powders containing various bentonite ratios were mixed in water to prepare slurry. The slurry was infiltrated into a polyurethane sponge. A high porous ceramic foam (preform) structure was achieved after burn out of the sponge. All ceramic preforms were sintered to increase stiffness (in the temperature range 900–1,350 °C). The sintered ceramic foams were subjected to compressive tests. The scanning electron microscopy was used to examine the reticulated ceramic foam structure, and X-ray diffraction analysis was performed to determine phases.     

Synthesis and characterization of monomeric and polymeric Cu(II) complexes of 3,4-ethylenedioxythiophene-functionalized with cyclam ligand

A functionalized EDOT derivative with 1,4,8,11-tetraazacyclotetradecane (cyclam) ligand pendant to the ethylene bridge (4) and its complexes [M(4)(BF₄)₂], where M(II) = Cu(II), was prepared and characterized. Their electrochemical copolymerization with EDOT was studied. The electro-co-polymerized films were characterized by electrochemical methods, X-ray photoelectron spectroscopy and by X-ray fluorescence spectroscopy. The co-polymerization method was found to afford a good control of the metal concentration in the polymer matrix and represents a good technique for preparing electronically conductive polymers containing redox-active metal complexes.     

New polymeric structures designed for the removal of Cu(II) ions from aqueous solutions

New polymeric structures obtained by chemical transformations of maleic anhydride/dicyclopentadiene copolymer with triethylenetetraamine, p‐aminobenzoic acid, and p‐aminophenylacetic acid were used for the removal Cu(II) ions from aqueous solutions. The experimental values prove the importance of the chelator nature and of the macromolecular chain geometry for the retention efficiency. The retention efficiency (η_r), the retention capacity (Q _e ), and the distribution coefficient of the metal ion into the polymer matrix (K _d ) are realized by evaluation of residual Cu(II) ions in the effluent waters, by atomic adsorption. Also are discussed the influence of pH, the thermal stability of the polymer, and their polymer–metal complex, as well as the particular aspects regarding the contact procedure and the batch time. Based on the polymers and polymer–metal complexes characterization a potential retention mechanism is proposed. All polymer supports as well theirs metal–complexes are characterized by ATD and FTIR measurements. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1397–1405, 2007     

Preparation and morphological investigation on bioactive ion-modified carbonated hydroxyapatite-biopolymer composite ceramics as coatings for orthopaedic implants

Bioactive ions (Mg, Sr, Zn) doped carbonated hydroxyapatite powders (dHAp) and pure carbonated hydroxyapatite (HAp) powders were prepared by wet chemical precipitation method. The bioactive ions were incorporated into the HAp matrix by co-precipitation from solution containing the appropriate amount of chloride salt of different ions. The morphology of pure HAp was mainly needle-like in nanometre size and the particles were disordered showing quasi-amorphous structure. The ion doping changed the morphology of particles, the dHAp particles had distorted spheroid shapes. Owing to the ion addition, the crystallinity of particles decreased. Particle aggregations can also be observed in both types of samples. HAp and dHAp loaded biopolymer polyvinylpyrrolidone (PVP) composite materials have also been developed by novel electrospinning technique. It has been shown that both the HAp and dHAp particles can be successfully incorporated into the PVP fibre web matrix and simultaneously the bioceramic powders were attached to the surface of polymer fibres. The surface of fibres was not fully covered with the particles. The ceramic powder addition to the polymer solution caused the polymer fibres to become more entangled and the diameters of fibres varied over a wider range compared to the base polymer fibres without bioceramic powder addition.