Structure Properties Of Poly Research Articles

Thermal Transitions and Structural Characteristics of Poly(3,4-ethylenedioxythiophene/cucurbit[7]uril) Polypseudorotaxane and Polyrotaxane Thin Films.

Herein, we report the thermal transitions and structural properties of poly(3,4-ethylenedioxythiophene/cucurbit[7]uril) pseudopolyrotaxane (PEDOT∙CB7-PS) and polyrotaxane (PEDOT∙CB7-PR) thin films compared with those of pristine PEDOT. The structural characteristics were investigated by using variable-temperature spectroscopic ellipsometry (VTSE), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and atomic force microscopy (AFM). VTSE and DSC results indicated the presence of an endothermic process and glass transition in the PEDOT∙CB7-PS and PEDOT∙CB7-PR thin films. X-ray diffraction of PEDOT∙CB7-PS and PEDOT∙CB7-PR powders displayed the presence of interchain π-π stacking revealing a characteristic arrangement of aromatic rings in the internal structure of the crystallites. AFM imaging of PEDOT∙CB7-PS and PEDOT∙CB7-PR thin films exhibited significant differences in the surface topographies compared with those of PEDOT. A high degree of crystallization was clearly visible on the surface of the PEDOT layer, whereas the PEDOT∙CB7-PS and PEDOT∙CB7-PR thin films exhibited more favorable surface parameters. Such significant differences identified in the surface morphology of the investigated layers can, therefore, be clearly associated with the presence of surrounding CB7 on PEDOT skeletons.

Electrical and Structural Properties of Poly (Methyl Methacrylate) Doped Potassium Iodide (KI) Solid Polymer Electrolyte

AbstractA high‐conducting salt‐doped polymer electrolyte layer has been created here for use in photocell technologies. The solution casting method is used to produce ion conducting film where poly (methyl methacrylate) (PMMA) is used as the host polymer and potassium iodide (KI) as the dopant. The conductivity and amorphic increases of the polymer electrolytes with the addition of salt concentrations helps in the enhancement of the charge transfer properties. Using electrochemical impedance spectroscopy (EIS), ionic conductivity is evaluated where maximum conductivity is 3.99 × 10−6 S cm‐1 at 20 wt% KI concentration. Polarized optical microscopy (POM) shows the reduction in crystallinity by salt doping, while Fourier transforms infrared spectroscopy (FTIR) shows the complexation as well as composite nature of the film. Ionic transference number (tion) measurement shows the predominantly ionic nature of this polymer electrolyte.

Structural properties of poly (Vinyl Chloride)-based polymer electrolytes

Solid polymer electrolyte of poly (vinyl chloride) PVC-sodium iodide (NaI) was prepared using solution casting technique. FTIR results suggested that NaI interacted with PVC. Deconvolution of FTIR spectra region were carried out to estimate the relative percentage of number of free ions at the C-Cl stretching vibration band. This result is in good agreement with the conductivity studies as well as the temperature studies.

Characterization of Poly(vinyl alcohol)/gelatin films made with winery solid by-product (vinasse) extract

The aim of this study is to examine the effect of grape pomace extract (GP) on the technological, functional and structural properties of Poly (vinyl alcohol) (PVA)/fish gelatin (FG) blend films. The addition of different ratios of GP (0 %, 0.5 %, 1 %, 1.5 % and 2 %) to PVA/FG edible films improved their rheological properties. The complex viscosity value increased exponentially when 2 % GP was added to the composite films compared to samples without any added GP. FTIR results showed that PVA and FG were able to interact with GP. The surface morphology indicated that addition of GP enhanced the intermolecular polymer interactions of the PVA-FG-GP combination. Atomic force microscopy (AFM) revealed that the films with GP had homogenous and smoother surfaces. X-ray diffraction (XRD) results confirmed that the FG and PVA chains interacted with GP, causing structural repositioning. Further confirmation of the effective interaction between PVA, FG and GP came from the decrease in crystallinity as the concentration of GP was increased. The melting temperature (Tm) was enhanced with the addition of GP. The combination of GP with PVA/FG films improved the plasticizer and surfactant properties thereby enhancing the flexibility of the films. The water solubility parameter was improved with the addition of GP without compromising the barrier properties. The antioxidant activity of the films increased significantly with the addition of GP. A GP-enriched PVA/FG film can be used as an edible film for food packaging purposes.

Electrostrictive and Structural Properties of Poly(Vinylidene Fluoride-Hexafluoropropylene) Composite Nanofibers Filled with Polyaniline (Emeraldine Base).

Previous studies have reported that poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) copolymers can exhibit large electrostrictive strains depending on the filler. This work examines the electrostrictive and structural properties of P(VDF-HFP) nanofibers modified with conductive polymer polyaniline (PANI). The P(VDF-HFP)/PANI composite nanofibers were prepared by an electrospinning method with different PANI concentrations (0, 0.5, 1, 1.5, 3 and 5 wt.%). The average diameter, water contact angle and element were analyzed by SEM, WCA and EDX, respectively. The crystalline, phase structure and mechanical properties were investigated by XRD, FTIR and DMA, respectively. The dielectric properties and electrostrictive behavior were also studied. The results demonstrated that the composite nanofibers exhibited uniform fibers without any bead formation, and the WCA decreased with increasing amount of PANI. However, a high dielectric constant and electromechanical response were obtained. The electrostrictive coefficient, crystalline, phase structure, dielectric properties and interfacial charge distributions increased in relation to the PANI content. Moreover, this study indicates that P(VDF-HFP)/PANI composite nanofibers may represent a promising route for obtaining electrostrictive composite nanofibers for actuation applications, microelectromechanical systems and sensors based on electrostrictive phenomena.

Degradation and Characterisation of Electrospun Polycaprolactone (PCL) and Poly(lactic-co-glycolic acid) (PLGA) Scaffolds for Vascular Tissue Engineering.

The current study aimed to evaluate the characteristics and the effects of degradation on the structural properties of Poly(lactic-co-glycolic acid) (PLGA)- and polycaprolactone (PCL)-based nanofibrous scaffolds. Six scaffolds were prepared by electrospinning, three with PCL 15% (w/v) and three with PLGA 10% (w/v), with electrospinning processing times of 30, 60 and 90 min. Both types of scaffolds displayed more robust mechanical properties with increased spinning times. The tensile strength of both scaffolds with 90-min electrospun membranes did not show a significant difference in their strengths, as the PCL and PLGA scaffolds measured at 1.492 MPa ± 0.378 SD and 1.764 MPa ± 0.7982 SD, respectively. All membranes were shown to be hydrophobic under a wettability test. A degradation behaviour study was performed by immersing all scaffolds in phosphate-buffered saline (PBS) solution at room temperature for 12 weeks and for 4 weeks at 37 °C. The effects of degradation were monitored by taking each sample out of the PBS solution every week, and the structural changes were investigated under a scanning electron microscope (SEM). The PCL and PLGA scaffolds showed excellent fibre structure with adequate degradation, and the fibre diameter, measured over time, showed slight increase in size. Therefore, as an example of fibre water intake and progressive degradation, the scaffold’s percentage weight loss increased each week, further supporting the porous membrane’s degradability. The pore size and the porosity percentage of all scaffolds decreased substantially over the degradation period. The conclusion drawn from this experiment is that PCL and PLGA hold great promise for tissue engineering and regenerative medicine applications.

Influence of accelerated weathering on the physical and structural properties of poly(lactic-acid)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PLA/PHBV) blends

Influence of accelerated weathering on the physical and structural properties of poly(lactic-acid)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PLA/PHBV) blends

Mechanical and structural properties of cellulose nanofiber/poly(vinyl alcohol) hydrogels cross-linked by a freezing/thawing method and borax

The effect of cellulose nanofibers (CNFs) on the mechanical and structural properties of poly (vinyl alcohol) (PVA) hydrogels cross-linked dually by a freezing/thawing method and a cross-linker (borax) was investigated using tensile tests, FT-IR measurements and synchrotron simultaneous small-angle/wide-angle X-ray scattering (SAXS/WAXS). The cross-linking with borax and addition of CNF greatly improved the tensile performance of the PVA hydrogels prepared in the freezing/thawing method, e.g., the dual cross-linking resulted in remarkable increase in the fracture strain, the Young’s modulus and the tensile strength. The fiber length effect on the mechanical properties of the CNF/PVA/borax hydrogels was examined, so that addition of CNF with longer fiber length increased the tensile modulus, whereas addition of CNF with shorter length caused extensibility higher than 1000% even at high CNF concentrations. SAXS/WAXS and FT-IR measurements have revealed that PVA was crystallized due to the freezing/thawing process, and both of PVA and CNF were cross-linked with borax, and hydrogen bonds between hydroxy groups of PVA (or/and CNF) were formed, indicating that the multiple cross-linking is effective for improvement of the tensile performance. In addition, the CNF/PVA/borax gel with the multi-physical cross-linking was found to possess the ability of the self-healing.

Evaluation of the structural and optical characters of PVA/PVP blended films

The effect of gamma irradiation on the optical and structural properties of poly(vinylalcohol) (PVA)/poly (vinylpyrrolidone) (PVP) blends was investigated in this study. The PVA/PVP films were formulated by mixing and casting method with increasing PVA ratios. The dried films were irradiated at 30 kGy and the impact of gamma irradiation on the characteristics of these films was inspected using FTIR, XRD, SEM and UV–vis techniques in the wavelength range (200–1200) nm. Swanepole method was used to compute the optical constants, optical band gap and complex dielectric constant whereas Wemple-DiDmenico model was applied to develop the optical dispersion parameters Eo and Ed. Additionally, the high frequency dielectric constant (ε∞) for all films was recorded. A slight shift in the FT-IR spectra and increase in the transmittance for all films post-irradiation were detected and the XRD analysis depicted the crystalline nature of the PVA/PVP films which was further confirmed by the surface morphology images obtained by the SEM. In conclusion, gamma irradiation and increasing the PVA to PVP ratio improved the optical properties of the films.

γ-Rays and ion beam irradiation effects on the optical and structural properties of poly (vinyl alcohol)-ethylene glycol composite

Poly (vinyl alcohol)-ethylene glycol (PVA-EG) composites were geared up using casting method. The PVA-EG composite films have been irradiated at various γ-rays irradiation doses and nitrogen ion beam. The optical and structural properties of the irradiated PVA-EG composites have been investigated using UV–Vis, FTIR and XRD analytical techniques. UV–Vis study illustrates the change in the optical band gap energy of the investigated samples. XRD investigations show several changes in the structure, crystal structure, intensity and position of the characteristic peaks for PVA-EG composite samples. The optical and structural properties were greatly dependent on the type of irradiation, extent of irradiation and exposure time.

Monte Carlo simulation of molecular and structural properties of mono- and bi-dispersed poly(ethylene oxide) nanofibers

Molecular and structural properties of poly(ethylene oxide), PEO, nanofibers with different diameters and molecular weights were investigated using Monte Carlo simulation of coarse-grained models on high coordination lattice. PEO nanofibers made up of mono- and bi-dispersed chains of CH3-(OCH2CH2)x-OCH3 where x = 13 to 53, with diameter ranged from 7.4 to 16.4 times the radius of gyration of PEO chains, were analyzed. For mono-disperse chains, as a result of increasing molecular weight, the bulk density increases and the molecular size at the surface is decreased more than the nanofibers composed of shorter chain length. There is higher degree of parallel orientation of the chains and bonds at the surface and a broader region over which this bond orientation pertains. For nanofibers with mixed molecular weight, shorter chains tend to segregate at the surface and the density of short chain component is higher in this region. Compared to mono-disperse nanofibers, the properties of longer chains do not significantly change, whereas the orientation of chains and bonds for low molecular weight polymers become more anisotropic orientation in the presence of longer chains.

Dielectric and Structural Properties of Poly(vinylidene fluoride) (PVDF) and Poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) Filled with Magnesium Oxide Nanofillers

This study examines the dielectric properties of filled PVDF film and filled PVDF-TrFE film incorporated with 1, 3, 5, and 7 weight percentages of magnesium oxide (MgO) nanofillers. The metal-insulator-metal (MIM) configuration demonstrates PVDF/MgO with 7 weight percent of MgO which produced high dielectric constant (1 kHz) with low dielectric loss. The ATR-FTIR spectra of PVDF/MgO (7%) indicate wide bonding peaks at 840 cm-1 and 880 cm-1, assigned to -CH2 and -CF2 groups, respectively. This implies the presence of high content of β-crystals in the PVDF/MgO (7%) film. A shift in the peak was observed in the same film, from 1170 cm-1 to 1180 cm-1 suggesting possible transformation from γ-crystals to β-crystals. This film showed no apparent defect on its film surface. Thus, it established that PVDF incorporated with 7% MgO can be used to produce nanocomposite thin film for low-frequency electronic devices.

Correlating diameter, mechanical and structural properties of poly(l-lactide) fibres from needleless electrospinning

The development and application of nanofibres requires a thorough understanding of the mechanical properties on a single fibre level including respective modelling tools for precise fibre analysis. This work presents a mechanical and morphological study of poly-l-lactide nanofibres developed by needleless electrospinning. Atomic force microscopy (AFM) and micromechanical testing (MMT) were used to characterise the mechanical response of the fibres within a diameter range of 200–1400 nm. Young’s moduli E determined by means of both methods are in sound agreement and show a strong increase for thinner fibres below a critical diameter of 800 nm. Similar increasing trends for yield stress and hardening modulus were measured by MMT. Finite element analyses show that the common practice of modelling three-point bending tests with either double supported or double clamped beams is prone to significant bias in the determined elastic properties, and that the latter is a good approximation only for small diameters. Therefore, an analytical formula based on intermediate boundary conditions is proposed that is valid for the whole tested range of fibre diameters, providing a consistently low error in axial Young’s modulus below 10%. The analysis of fibre morphology by differential scanning calorimetry and 2D wide-angle X-ray scattering revealed increasing polymer chains alignment in the amorphous phase and higher crystallinity of fibres for decreasing diameter. The combination of these observations with the mechanical characterisation suggests a linear relationship between Young’s modulus and both crystallinity and molecular orientation in the amorphous phase. Statement of significanceFibrous membranes have rapidly growing use in various applications, each of which comes with specific property requirements. However, the development and production of nanofibre membranes with dedicated mechanical properties is challenging, in particular with techniques suitable for industrial scales such as needleless electrospinning. It is therefore a key step to understand the mechanical and structural characteristics of single nanofibres developed in this process, and to this end, the present work presents changes of internal fibre structure and mechanical properties with diameter, based on dedicated models. Special attention was given to the commonly used models for analyzing Young’s modulus of single nanofibers in three-point bending tests, which are shown to be prone to large errors, and an improved robust approach is proposed.

Effect of localized surface plasmon resonance from incorporated gold nanoparticles in PEDOT:PSS hole transport layer for hybrid solar cell applications

We report optical and structural properties of poly (3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) incorporated gold nanoparticles capped by citrates (Au-citrates) as hole transport layer for hybrid organic-inorganic solar cell applications. PEDOT:PSS and Au-citrates both are water solution and the mixed are done in 2.378 wt%, 2.978 wt% and 3.144 wt% of Au-citrates. Plasmonic peak in the wavelength area of ∼525 nm for Au-citrates is found quite stable after addition of iso-propanol for wettability purpose. In our result, enhanced absorbance spectra of PEDOT:PSS incorporated Au-citrates indicates the effect of localized surface plasmon resonance from Au-citrates and it is estimated to enhance performance of hybrid solar cell efficiency. Optical properties of the thin films in hybrid solar cell device are done in the structure of ITO/ZnO/P3HT:PCBM(active layer)/(PEDOT:PSS:Au-citrates). The complete layer structure shows the enhancement of optical property in all UV-vis region in comparison to that structure without Au-citrates.

Novel carbon nanospheres and poly(9-vinylcarbazole) composites: Synthesis, structural and photo-physical properties of films elaboration

The photophysical and structural properties of poly(9-vinylcarbazole) and carbon nanospheres (CNS) based composites are investigated. The effect of CNS on the optical and vibrational properties of the new synthesized composite with several concentration weights (1.7, 3 and 5%) and also charge transfer process were examined by various optical and structural characterizations. Scanning and transmission electron microscopy were indented to show the morphology of CNS and their distribution on PVK matrix. States and time resolved photoluminescence decays of composites were used to evidence the charge transfer and dynamical properties of their excited states. The stability and the graphitized degree of CNS were found by Raman scattering analysis.

Uniaxial tensile and structural properties of poly(vinyl alcohol) films: The influence of heating and film thickness

ABSTRACTPoly(vinyl alcohol) as pure or composite materials is widely used in the food and textile industries, andbiomedical applications due to some important properties such as uniaxial tensile, biocompatibility, and noncarcinogenicity. Investigation of the influence of the film thickness and heating on the uniaxial tensile, spectroscopic, and surface properties of PVA films investigated in this study is quite important for improving the properties of such materials and their applicability in different conditions. In this study, with the influence of heating, a necking behavior was observed at around 2% for thin films and 4–9% strain for thicker PVA films for which a kind of transition point at around 1–2% strain was observed. The mechanical strength of PVA films, strain at break, and Young's modulus were enhanced greatly as the temperature increased from 80 to around 110 °C, and then most of them decreased. The degree of crystallinity increased linearly with the heat temperature from around 36–40%. Although PVA thin films obtained a very smooth surface structure after being heated at 80 °C, with increasing heat temperature, the surface roughness of both thin and thick PVA films increased and the PVA thin films obtained more degraded film surface. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44915.

The effect of nano-TiO2 and SiO2 on bonding strength and structural properties of poly (vinyl acetate) composites

Abstract Polyvinyl acetate (PVAc) is a thermoplastic polymer widely used in the furniture industry. It has many advantages such as easy processing, cheap, biodegradable; but, resistance to water and hot medium is not enough to the application area. In this study, the effect of nano-TiO 2 and nano-SiO 2 on bonding performance and structural properties of PVAc were investigated. Bonding strength with block shear test and structural properties with thermogravimetric analysis-TGA, X-ray diffraction-XRD, and transmission electron microscopy-TEM of PVAc were determined. The obtained results showed that bonding strength with cooperating both TiO 2 and SiO 2 for 1% and 2% were improved. XRD and TEM results proved to be the homogenously interactions for 1% and 2% between nano fillers and matrix. TGA results showed that thermal stability of PVAc blends was largely improved.

Secondary doping in poly(3,4‐ethylenedioxythiophene):Poly(4‐styrenesulfonate) thin films

ABSTRACTThe electrical and structural properties of poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) thin films deposited from aqueous dispersion using different concentrations of selected secondary dopants are studied in detail. An improvement of the electrical conductivity by three orders of magnitude is achieved for dimethyl sulfoxide, sorbitol, ethylene glycol, and N,N‐dimethylformamide, and the secondary dopant concentration dependence of the conductivity exhibits almost identical behavior for all investigated secondary dopants. Detailed analysis of the surface morphology and Raman spectra reveals no presence of the secondary dopant in fabricated films, and thus the dopants are truly causing the secondary doping effect. Although the ratio of benzenoid and quinoid vibrations in Raman spectra is unaffected by doping, the phase transition in PEDOT:PSS films owing to doping is confirmed. Further analysis of temperature‐dependent conductivity reveals 1D variable range hopping (VRH) charge transport for undoped PEDOT:PSS, whereas highly conductive doped PEDOT:PSS films exhibit 3D VRH charge transport. We demonstrate that the charge‐hopping dimensionality change should be a fundamental reason for the conductivity enhancement. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1139–1146

Doping effect of dodecyl benzene sulphonic acid in poly(3-hexylthiophene)-P3HT-films

We demonstrated that how dodecyl benzene sulphonic acid (DBSA) as a small-molecular dopant, affects the spectroscopic, electronic and structural properties of poly(3-hexylthiophene) (P3HT). The DBSA volume ratio was varied from 0.001μL to 30μL per 1mL P3HT solvent in p-xylene. DBSA doping reaction was confirmed by the emerging huge absorption peak at the wavelength of ∼800nm while the ionization potential and nanostructure of P3HT films were highly affected. Additionally, conductivity of P3HT films increased nearly 1000times at 30μL DBSA. The crystallinity, as well as the conductivity and the UV–Vis absorption changed with the presence of P3HT. P3HT grain sized crystals seems to be disturbed by the addition of DBSA, but still remained even more DBSA was introduced. DBSA doping has interesting properties when incorporated in OFTs, OPVs and bioelectronics applications, so addition of DBSA can open new pathways for structural, spectroscopic and electronic control of organic semiconductor’s blends.

Complementary study on the electrical and structural properties of poly(3-alkylthiophene) and its copolymers synthesized on ITO by electrochemical impedance and Raman spectroscopy

Targeting the use of organic conjugated polymers in organic solar cells, this study looks at the electrochemical properties of poly(3-alkylthiophene) films: poly(3-methylthiophene), poly(3-hexylthiophene), poly(3-octylthiophene) and its copolymers electrochemically synthesized on a tin-doped indium oxide (ITO) substrate. Electrochemical impedance spectroscopy (EIS) was used to monitor the change in the electrochemical behavior of these films on the ITO and the charge transfer resistance (RCT) values were determined in open circuit potential (OCP) and at different overpotentials. Together with the EIS, the ex situ and in situ Raman spectroscopy was used to characterize the influence of aromatic radical cation and dication species, present in the polymer matrix of homo and copolymers, in the management processes seen in the Nyquist and Bode-phase diagrams for different systems obtained on ITO. The EIS results in OCP showed an decrease in resistance demonstrating increased conductivity with the copolymerization, and through the Bode-phase diagram and the ex situ Raman spectra, these changes were related to the oscillation of the radical cation and dication along the polymer matrix. By studying Nyquist and Bode-phase diagrams in the overpotentials, an increase in RCT values in higher potentials was seen that could be related to the bipolaronic process, which after the deconvolution of the in situ Raman spectra, was possible to relate these results to the stabilization of the dication species in the homo and copolymers matrix when subjected to high potential.