Influence of preparation conditions on the physical properties of zein films

Zein is a hydrophobic protein produced from maize. Biodegradable zein films without additional reagents were prepared using various controlled drying conditions. The zein films were transparent. Mechanical properties (tensile strength and puncture strength), gas permeability, and water vapor permeability (WVP) of the zein films were measured. The tensile strengths of the zein films were between 7 and 30 MPa and the puncture strengths between 37 and 191 MPa. The zein films had higher oxygen permeability than carbon dioxide permeability. The lowest WVP of the zein film was 0.012×10⁻⁹ g·m/m²·s·Pa. We found differences in the WVP between the sides of the zein films; i.e., the air side of the zein film had a higher WVP than the basal side of the zein film when the films were exposed to high humidity during testing. This indicates a relationship between the WVP of the zein film and the contact angle of the zein film. The mechanical properties of the zein film depended on the drying conditions during preparation. Zein films with various useful physical mechanical properties were produced.     

Synthesis and characterization of a plant cutin mimetic polymer

A mimetic polymer of plant cutin have been synthesized from 9,10,16-trihydroxyhexadecanoic (aleuritic) acid through a low temperature polycondensation reaction. Reaction conditions (solvent, catalyst, temperature, etc…) were studied and modified to optimize yield and product characteristics. The resulting polyaleurate polymer was characterized by Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) and solid state ¹³C-Cross Polarization/Magic Angle Spinning Nuclear Magnetic Resonance (¹³C-CP/MAS NMR). Mechanical and hydrodynamic properties were also investigated. In the average, the product obtained is physically and chemically very similar to plant cutin (a hydrophobic polyester). However, a more detailed analysis of results reveals that polyaleurate framework is more rigid than natural cutin and with additional larger short-range ordered domains. Also, the synthetic polymer displays slightly different mechanical properties with respect to natural cutin. Additional hydrogen bonding within the framework of polyaleurate is considered to be responsible for such experimental observations.     

A one‐step approach for esterification of zein with methanol

Zein (corn protein) was reacted with methanol in the presence of para‐toluenesulphonic acid under mild conditions to give a material formed by esterification of predominantly the amide groups of the protein. The formation of methyl zeinate was confirmed by proton NMR. The new signal appeared at 3.67 ppm in zein methylation product, which is absent for pure zein can be assigned to the protons of the CH₃ group of an ester. The strong C?O stretching vibration due to the presence of ester group in the region of 1739 cm^?1 in case of methylated zein was also noticed from FTIR studies. The increase in the C : N atom ratio in the zein methylation product obtained from elemental analysis results further indicates the conversion of a significant proportion of the ? CONH₂ groups in zein to ? COOCH₃ groups in the esterified product. The methylated product had glass transition temperature about 20°C lower than that of the unmodified zein. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Plasmonic organic bulk–heterojunction solar cells based on hydrophobic gold nanorod insertion into active layers

In this work, we fabricated plasmonic organic bulk–heterojunction solar cells by inserting hydrophobic gold nanorods (GNRs) into the active layers. Power conversion efficiency was improved from 7.43% to 8.22% because the plasmonic effect of GNRs improved the light harvesting efficiency. Maximum exciton generation rate was increased from 1.35 × 10⁻²⁶ to 1.51× 10⁻²⁶m⁻³ s⁻¹, and the electron mobility was also increased from 8.6 × 10⁻⁵ to 1.5× 10⁻⁴cm⁻² V⁻¹ s⁻¹. As a result, the short circuit current density was improved from 15.5 to 16.7 mA cm⁻²—the dominant reason for performance enhancement. The open circuit voltage and fill factor were improved simultaneously. The plasmonic device showed a highest PCE of 8.43%, indicating that doping GNRs into active layers is a simple and effective way to fabricate high‐performance organic solar cells. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45920.     

Conductivity measurements of electrodeposited polypyrrole

Thick, freestanding, flexible films of polypyrrole have been prepared from propylene carbonate solutions of pyrrole monomer containing tetra-ethyl ammoniump-toluene sulphonate electrolyte The conductivity of the films was found to vary with orientation of the sample, deposition temperature and time. Conductivities of up to 338.4 S cm^–1 were attained with samples prepared at 0°C. XRD analyses have revealed a difference in structure with sample orientation which affects the conductivity of the material significantly.     

High-temperature resistant polyimide-based sandwich-structured dielectric nanocomposite films with enhanced energy density and efficiency

Development of advanced dielectric materials with both high-electric energy density and high-temperature resistant attributes is highly desirable in modern electronics and electrical systems. Herein, a series of polyimide (PI)-based sandwich-structured dielectric nanocomposite films have been attempted to develop the advanced high-temperature resistant capacitor films, wherein the boron nitride nanosheets/PI nanocomposite acts as the outer layers and the zinc oxide (ZnO)/PI as the middle layer. Benefitting from the merits of both fillers and the unique structure, the resulting nanocomposite films can simultaneously achieve both high-dielectric constant and high-breakdown strength, as well as low-electrical conduction loss, thus leading to improved discharged energy densities (U_e) and charge/discharge efficiency (η) at elevated temperatures. It is found that the sandwich-structured nanocomposite film with 0.4 vol% ZnO (0.4ZnO/PI-S) can deliver a maximum U_e of 5.29 J cm⁻³ at 400 MV m⁻¹ and 150°C, which is about 1.9 times that of the pristine PI film. Moreover, outstanding dielectric stability over 10,000 charge/discharge cycles has been demonstrated in such PI-based sandwich-structured nanocomposite films at 150°C and 200 MV m⁻¹. This research may provide a new paradigm to explore polymer nanocomposites having excellent energy storage and efficiency at elevated temperatures.     

An ambient-temperature superionic conductive,electrochemically stable,plastic cross-linked polymer electrolyte for lithium metal battery

A plastic cross-linked polymer is prepared using acrylonitrile as a monomer and poly(ethylene glycol diacrylate) as a linking agent. A phase diagram-guide rational design is introduced to fabricate the polymer composite electrolyte in the case of succinonitrile complexed with lithium bis-trifluoromethanesulfonimide. The plastic cross-linked polymer-based electrolyte films with ambient-temperature superionic conductivity (2.33 mS cm⁻¹) and a wide electrochemical window (0–5.6 V vs. Li/Li⁺) have been demonstrated. The charging and discharging experiments of the plastic polymer composite electrolyte-based lithium batteries show that the plastic polymer electrolyte can cycle normally and safely at a current density of 0.5 mA cm⁻². These batteries exhibit excellent average coulombic efficiency of 98.5% in the first 150 cycles. The initial capacity at 25°C is 127.5 mAh g⁻¹ (0.2 C), which is close to the value achieved by liquid-electrolyte-based cells under similar conditions. The capacity retention is 91% after 150 cycles.     

Electrical properties of thick boron and nitrogen contained CVD diamond films

The acceptor and donor defects of thick (approx. 0.4 mm) free-standing boron and nitrogen containing microwave plasma CVD polycrystalline diamond films were investigated. Charge-based deep level transient spectroscopy (Q-DLTS) was applied to study impurity-induced defects, their density and energy distribution in the energy range of 0.01 eV≤E−E_v≤1.1 eV above the valence band. It was shown, that differential capacitance–voltage, and Hall effect measurements combined with DLTS data can be used to determine the degree of compensation, and the concentration of compensating donors (mostly the positively charged single-substitutional nitrogen (N⁺)) in p-type CVD polycrystalline diamond films. It was found, that incorporated boron atoms induce three levels of electrically active defects. Two of them with concentration (2–3)×10¹⁶ cm⁻³ each have activation energies of 0.36 and 0.25 eV with capture cross-sections of 1.3×10⁻¹³ and 4.5×10⁻¹⁹ cm², respectively. The third type of defect has an activation energy of 0.02 eV, capture cross-section 3×10⁻²⁰ cm² and concentration 10¹⁵ cm⁻³, this shallow trap being a probable general caterer of holes in low-doped films. The total concentration of electrically active uncompensated acceptors in all p-type diamond samples was approximately 2×10¹⁷ cm⁻³ with hole concentration of approximately 1.5×10¹⁴ cm⁻³ and hole mobility in the range of 30–40 cm² V⁻¹ s⁻¹ at room temperature. If assumed that compensating donors are mostly nitrogen, the films contained no less than 3×10¹⁶ cm⁻³ of N⁺.     

A “chain fold band” in the infrared spectra of nylon 6

An absorption band found at 974 cm⁻¹ in the infrared spectra of “amorphous” nylon 6 films has been assigned to CH₂ wagging or twisting vibrations in molecular chain folds. Annealing amorphous films in air at increasing temperatures up to 150°C has been shown to induce a steady increase in the intensity of the absorption band at 974 cm⁻¹. Annealing at higher temperatures resulted in a sharp decrease in intensity up to an annealing temperature of 210°C. This sharp decrease coincided with a sharp increase in the long period determined by low-angle x-ray diffraction studies. Drawing amorphous films has been shown to induce a decrease in the intensity of the band at 974 cm⁻¹. Polarized infrared investigations of amorphous drawn films revealed that the band at 974 cm⁻¹ was strongly perpendicular in character. Treatment of amorphous films in water induced no frequency change in the band at 974 cm⁻¹.     

Membrane Electrode Assembly with Ultra Low Platinum Loading for Cathode Electrode of PEM Fuel Cell by Using Sputter Deposition

Cathode electrodes of proton exchange membrane fuel cells were fabricated by using Pt sputter deposition to increase the gravimetric power density (W mg_Pt⁻¹) with reduced Pt loading. Ultra low Pt‐based electrodes having Pt loading in between 0.0011 and 0.06 mg_Pt cm⁻² were prepared by a radio frequency (RF) sputter deposition method on the surface of a non‐catalyzed gas diffusion layer (GDL) substrate by changing the sputtering time (20, 90, 180, 1050 s). The effect of cathode Pt loading on the performance of membrane electrode assembly were investigated using polarization curve, impedance, H₂ crossover and cyclic voltammetry techniques. The effect of backpressure on PEMFC performance was also investigated. Sputter1050 (0.06 mg_Pt cm⁻²) exhibited the best power density at 80 °C cell temperature and without backpressure for H₂/O₂, 100 %RH (297 mW cm⁻² and 5 W mg_Pt⁻¹ at 0.6 V). On the other hand sputter90 (0.005 mg_Pt cm⁻²) showed the peak gravimetric power density (15 W mg_Pt⁻¹ and 75 mW cm⁻² at 0.6 V). The Pt utilization efficiency increased as the Pt loading decreased. Sputter20 and sputter90 electrodes yielded insufficient electrochemical surface area (ECSA), higher charge transfer and ohmic resistance, but sputter180 and sputter1050 yielded sufficient ECSA and lower charge transfer and ohmic resistance.     

High speed tensile performance and fractography of acrylic latex films

The performance of acrylic (50:50 MMA/BuA) latexes was investigated as a function of fusion level using high speed tensile testing. The structure of the copolymer was varied via the addition of molecular weight modifiers to the emulsion polymerizations. Chain transfer agent (CBr₄) was used to reduce the copolymer modulus, and crosslinker (EGDM, ethylene glycol dimethacrylate) was added to increase the modulus. The resulting materials exhibited a wide range of viscoelastic behavior (G^* varied from ～ 10⁷ dyne cm^?2 to ～ 10⁹ dyne cm^?2). Fracture energy and peak force at break were measured as a function of the complex modulus. It was found that both of these parameters showed a maximum with respect to G^* that corresponded to intermediate levels of crosslinking. This observation was explained in terms of the degree of coalescence of the films. Fully fused films (excess CBr₄) were brittle and performed poorly, conceivably because of insufficient entanglement to support stress. Marginally fused films also exhibited inferior, brittle behavior. The films cast from latexes synthesized with low levels of molecular weight modifiers showed intermediate fusion levels and superior tensile performance. The quantitative results were rationalized using scanning electron microscopy (SEM) of both the virgin films and the fracture surfaces. For comparison, the same materials were tested in a fully fused state following hot pressing. The behavior paralleled that expected for vulcanized rubbers in which lightly crosslinked materials exhibit the highest tensile strength. © 1993 John Wiley & Sons, Inc.     

Toughening of thermoset green zein resin: A comparison between natural rubber-based additives and plasticizers

Zein-based brittle thermoset green resin was toughened using sorbitol, natural rubber fibers (NRF), and epoxidized natural rubber fibers (ENRF). NRF and ENRF were electrospun directly into zein slurry. Chemical, thermal, and mechanical properties of zein resin containing NRF (Zein/NRF) and ENRF (Zein/ENRF) were compared with those of sorbitol-plasticized zein. NRF was found to be immiscible in zein and Zein/NRF resins showed two distinct glass transition temperatures (T _g), whereas Zein/ENRF specimens showed significant increases in both T _g and degradation temperature (T _d) due to crosslinking between zein and epoxidized natural rubber. ENRF was more effective in enhancing fracture toughness of zein than NRF or sorbitol. Increased ENRF loading to 15 wt % showed significant increase in toughness with minimal decreases in strength and Young's modulus. Sorbitol and NRF were unable to improve the toughness of zein resin significantly. Environment-friendly zein/ENRF resin with higher fracture toughness developed in this study would be suitable in many applications including green composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48512.     

Bitter potato starch-based film enriched with copaiba leaf extract obtained using supercritical carbon dioxide: Physical–mechanical,antioxidant, and disintegrability properties

Films based on bitter potato starch (BPS) and its blends with chitosan (BPS-Ch) or soy protein isolate (BPS-SPI) loaded with copaiba leaf extract (E) are prepared via the casting method. The physical–mechanical and antioxidant properties of the as-prepared films are compared with those of a control. Moreover, the half-maximal degradation (t₅₀) of the prepared films is calculated by fitting the Hill model to disintegrability kinetic data. Among the analyzed films, BPS-Ch-E exhibits the lowest (p < 0.05) solubility in water and opacity, strongest water vapor-barrier (3.58 × 10⁻¹¹ g m⁻¹ s⁻¹ Pa⁻¹), and highest tensile strength and elongation at break. The Fourier transform infrared spectra of BPS-Ch-E and BPS-SPI-E demonstrate new peaks at 1550, 1239, and 1070 cm⁻¹ corresponding to N H and C O stretching. The BPS-E and BPS-Ch-E surfaces are devoid of scratches and phase separation. The incorporation of E significantly increases the antioxidant activity of the films. BPS-SPI-E and BPS-Ch-E demonstrate the lowest (t₅₀ ≈ 1.4 days) and highest (t₅₀ ≈ 3.5 days) disintegration rates, respectively, among the prepared films. E loading facilitates the development of films possessing beneficial physical–mechanical and antioxidant properties as well as rapid disintegrability, enabling their potential application as a eco-friendly packaging material.     

Development and properties of zein/Tremella fuciformis polysaccharides blend as a hard capsule material

Replacement of animal-derived capsules with those of plant origin, which are safe and stable, is the development tendency at present. However, properties of pure plant materials, such as high hydrophobicity, low solubility, and poor film-forming ability, restrict the popularization and application of plant capsules. In the present study, a novel blend of zein and Tremella fuciformis polysaccharides (TPS) was developed by a facile one-step shear method. Properties of the blend were investigated to show its potential in being used as raw materials for capsule shells. According to viscosity, rheological behaviors, and microscopic morphology of the blends, TPS molecules enhance both the stability and gelling functions of the mixture by wrapping around the zein aggregations. It was revealed that the viscosity of the zein/TPS system increases with the zein content, while the elasticity of it increases with the TPS content. The films obtained from the blends were characterized by mechanical properties and SEM, showing a zein/TPS mass ratio of 7:3 leads to the most appropriate TS and highest EAB among all films tested. The FTIR and XRD analysis suggested the physical mixing of zein and TPS in the blend films. As shown by the DSC curves, the glass transition temperature (Tg) of the blend film gradually dropped with the addition of TPS, which was a consequence of the weakening of intermolecular interactions. The paper introduced the whole process, from raw material preparation to ZT capsule production, further verifying the application potentials of such a novel plant material.     

Corrosion behavior of electrodeposited Wo3 thin films

In this study, nanostructured tungsten trioxide (WO₃) thin films were deposited on Indium tin oxide (ITO)-coated glass substrate using electrochemical deposition (ECD). After deposition, the films were annealed at 450 °C for 2 h in an air atmosphere. X-ray diffraction (XRD) analysis confirmed that the prepared WO₃ thin films have crystalline phases. According to the absorption measurements, the optical bandgap of the WO₃ film was calculated as Eg 2.80 eV. Based on the scanning electron microscopy (SEM) images, the surface morphology of the thin films was influenced by deposition conditions. Raman spectroscopy analysis was also used to further examine the structure and chemical compositions of the thin films. The nature of the nanostructured WO₃ thin films was studied with Electrochemical Impedance Spectroscopy (EIS) and Tafel. Nyquist, open circuit potential and Bode analysis were used to evaluate structural changing and corrosion behavior of the prepared WO₃ thin films. With the help of these measurements and analyzes, the parameters such as solution resistance (Rs), polarization resistance (Rpo), a constant phase element (CPE) and a CPE exponent (n) were calculated as 43.43 Ω cm², 2.67 × 10⁶ Ω cm², 18.45 × 10⁻⁶ Ω⁻¹ s cm⁻², 0.958, respectively. Also, the corrosion features of the WO₃ thin films were investigated with the help of tafel measurements and the corrosion potential and current values were calculated as −0.583 V and 5.09 × 10⁻¹⁵ A, respectively. It is thought that the prepared thin film might have the potential to be used industrially with these features.     

Influence of nucleation density on film quality,growth rate and morphology of thick CVD diamond films

The optimum growth parameters of our 5 kW microwave plasma CVD reactor were obtained using CH₄/H₂/O₂ plasma and high quality transparent films can be produced reproducibly. Among the films prepared in this system, the film of best quality has very smooth crystalline facets free of second nucleation and the full width at half maximum (FWHM) of the diamond Raman peak is 2.2 cm⁻¹, as narrow as that of IIa natural diamond. For this study, diamond films were grown on silicon substrates with low (10⁴–10⁵ cm⁻²) and high nucleation densities (>10¹⁰ cm⁻²), respectively. From the same growth run, a highly 〈110〉 textured 300 μm thick white diamond film with a growth rate of 2.4 μm/h was obtained from high nucleation densities (>10¹⁰ cm⁻²), and a white diamond film of 370 μm in thickness with a higher growth rate of 3 μm/h was obtained from low nucleation densities (5×10⁴–10⁵ cm⁻²) too. The effect of nucleation density on film quality, growth rate, texture and morphology was studied and the mechanism was discussed. Our results suggest that under suitable growth conditions, nucleation density has little effect on film quality and low nucleation density results in higher growth rate than high nucleation density due to less intense grain growth competition.     

In-Situ Infrared Study of the Synthesis of Polyaniline Under Acid and Neutral pH

In-situ infrared study of polyaniline (PANI) synthesis showed that the reaction initiated at pH = 1.5 produced a granule PANI microstructure via para-linked dimers of 4-aminodiphenylamine, exhibiting γ(C–H) at 802 cm⁻¹; the reaction initiated at pH = 5.0 and 7.0 produce fiberous, and planar microstructures via ortho-linked dimers of 1,2-aminodiphenylamine and phenazine, exhibiting γ(C–H) at 738 and ν(C=N) at 1446 cm⁻¹. The doped PANI that was produced at pH less than 5.0 showed a feature-less IR background absorption above 1600 cm⁻¹. This absorption could correspond to π-electron delocalization as an indicative of polyaniline conductivity.

     

Studies on glass transition temperature of mono and bilayer protein films plasticized by glycerol and olive oil

Thermomechanical and thermal properties of whey protein, maize prolamin protein (zein), and the laminated whey protein–zein films were studied. The dynamic mechanical (thermal) analysis (DMTA) results showed that the single zein film had higher T_g than single whey protein and zein–whey laminated films. The shift in the T_g values of films from 31.2°C in whey protein film and 88.5°C in the zein film to 82.8°C in the laminated whey protein–zein films may be implied some interaction formation between the two polymers. The small tan δ peaks were observed at ?50°C in zein–glycerol films and at ?22.37°C in the whey protein films and can be related to β‐relaxation phenomena or presence of glycerol rich region in polymer matrix. Zein‐olive oil and zein–whey protein–olive oil films showed tan δ peaks corresponded the T_g values at 113.8, and 92.4°C, respectively. Thus, replacing of glycerol with olive oil in film composition increased T_g. A good correspondence was obtained when DSC results were compared with the tan δ peaks in DMTA measurements. DSC thermograms suggested that plasticizers and biopolymers remained a homogeneous material throughout the cooling and heating cycle. The results showed that T_g of zein–glycerol films predicted by Couchman and Karasz equation is very close to value obtained by DSC experiments. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Nucleation and growth of diamond films on aluminum nitride by hot filament chemical vapor deposition

Nucleation and growth of diamond films on aluminum nitride (ALN) coatings were investigated by scanning electron microscopy, Raman spectroscopy and scratch test. ALN films were grown in a magnetron sputtering deposition. The substrates were Si(111) and tungsten carbide (WC). Chemical vapor deposition (CVD) diamond films were deposited on ALN films by hot filament CVD. The nucleation density of diamond on ALN films was found to be approximately 10⁵ cm⁻², whereas over 10¹⁰ cm⁻² after negative bias pre-treatment for 35 min was −320 V, and 250 mA. The experimental studies have shown that the stresses were greatly minimized between diamond overlay and ALN films as compared with WC substrate. The results obtained have also confirmed that the ALN, as buffer layers, can notably enhance the adhesion force of diamond films on the WC.     

Filament metal contamination and Raman spectra of hot filament chemical vapor deposited diamond films

Chemical vapor deposited diamond films grown in a hot filament reactor using three filament metals (tungsten, tantalum, and rhenium) have been analyzed for their metal impurity content. This is the first report wherein all three common CVD filament metals have been examined and a single technique used for diamond film analysis. Tungsten carbide filaments yielded the lowest impurity level (few ppm by mass), whereas rhenium yielded the highest (parts per thousand). The effects of filament temperature and addition of ammonia or oxygen to the reactant gas mixture were examined. A correlation was observed between the metal content of the product films and their quality, as judged using Raman spectroscopy. Films with the highest metal content yielded Raman spectra showing the lowest fluorescence background, the smallest sp² carbon contribution, and the narrowest 1332 cm⁻¹ diamond line.