Host Polymer Matrix Research Articles

Predominantly chain segmental relaxation dependent ionic conductivity of multiphase semicrystalline PVDF/PEO/LiClO4 solid polymer electrolytes

The solid polymer electrolyte (SPE) films comprise poly(vinylidene fluoride) (PVDF)/poly(ethylene oxide) (PEO) blend (75/25 wt/wt%) as host polymer matrix with lithium perchlorate (LiClO4) as ionic dopant for different salt concentrations (i.e., 5, 10, 15, 20, 25, and 30 wt%), and also varying compositional weight ratio PVDF/PEO blends (i.e., 75/25, 50/50, 25/75, and 10/90 wt/wt%) with 25 wt% concentration of LiClO4 were prepared by solution casting at 70 °C. The results obtained from X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy revealed that there is enormous alteration in the α- and β-phase crystals of the PVDF and the size and content of the PEO crystallites, and also the degree of crystallinity of these SPE materials with the variation of salt concentration and the polymer blend composition. Dielectric relaxation spectroscopy (DRS) was employed over the frequency range from 20 Hz to 1 MHz, at 27 °C for the study of the complex impedance, dielectric permittivity, dielectric loss tangent, ac electrical conductivity, and electric modulus spectra of the SPE films. All these spectra were analyzed separately and simultaneously by a novel ‘master curve representation’ procedure to unveil the contribution of various dielectric polarization processes (i.e., electrode, interfacial, molecular (dipolar), and the ionic) and their relaxations which are exhibited with increasing order of frequency and have substantial overlapping with the adjacent processes in these heterogeneous ion conducting materials. The loss tangent spectra of these materials manifest prominent dielectric relaxation peaks which attribute to the cation coordinated polymer chain segmental dynamics. The high frequencies ac electrical conductivity data of all these materials obey the power law, whereas the Nyquist plots of impedance data exhibit reasonably distinguishable bulk and electrode polarization frequency regions for the electrolytes having salt concentration ≥20 wt%. The inverse correlation observed between the relaxation time and the dc ionic conductivity establishes that the transportation of ions is predominantly coupled to the polymer chain segmental motion which assists the hopping between favourable conduction sites in the ion-dipole complexes. The SPE films are comparatively stiffer and have a slightly higher degree of crystallinity when the salt concentration is ≤ 15 wt% and they exhibit distinct dielectric, dc ionic conductivity, and relaxation behaviour as compared to that of the softer and lower crystallinity films having salt concentration ≥20 wt%. These SPE films possess good electrochemical performance and close-to-unity total ion transference numbers. Among these two sets of the SPE films, the maximum dc ionic conductivity was noted 2.01 × 10−5 S/cm at 27 °C for the 75PVDF/25PEO–30 wt% LiClO4 film from the set of different salt concentrations, and 5.61 × 10−6 S/cm for 25PVDF/75PEO–25 wt% LiClO4 film from the set of varying compositions of the polymer blend matrix. The considerable ionic conductivity values of these SPE films at ambient temperature and also their promising electrochemical performance corroborate them as novel ion conductors suitable for the development of solid-state rechargeable lithium-ion batteries.

Impedance and electrochemical studies of rGO/Li-ion/PANI intercalated polymer electrolyte films for energy storage application

The present manuscript describes the synthesis of reduced graphene oxide (rGO) from coke by using modified Hummers method. The synthesized emeraldine poly aniline (PANI) polymer was used as a polymer host matrix. A series of polymer electrolyte films were prepared by varying concentration of rGO, PANI and Lithium carbonate. The synthesized PANI and rGO were soluble in common polar solvent. The structural, Nyquist and cyclic voltammetry studies of polymer electrolyte were investigated. The XRD and FTIR investigation confirms the formation of rGO and PANI in view of structural and chemical compositions respectively. The electrical property of polymer electrolyte was obtained by Nyquist plot which represents the perfect semicircular pattern. It confirms the charge transport mechanism with the decreased concentration of rGO in polymer electrolyte. The cyclic voltammetry performed at different scan rate on potential window ranged between -0.5 to 0.6 V represents the oxidation and reduction peaks. The overall results describe that the present electrolyte material can be a potential candidate for energy storage application.

Spectroscopic study of trivalent rare earth Sm3+ ions doped PVA + PEG blended polymer films

The concentration varied trivalent active lanthanide Sm3+ ions of 0–5 mol % doped complex miscible host polymer blends of Poly (vinyl alcohol) (PVA) and Poly (ethylene glycol) (PEG) were prepared by the universal solution casting technique and their spectroscopic characteristic features was examined through optical absorption and photoluminescence analysis. The optical absorption analysis of Sm3+ doped polymeric samples used for investigation and prediction of the optical parameters. The optical band gap energy (Eg) was evaluated from the Tau’c extrapolation and is found decreased with increasing Sm3+ ions concentration. From the photoluminescence analysis the high intense reddish orange emission peak at 595 nm corresponding to 4G5/2 → 6H7/2 transition was observed in under the 401 nm excitation wavelength which may be used as active laser medium. The decay curves of the polymer blends are exhibiting non exponential nature. The Life time and efficiency of the PVAEG: Sm3+ (5 mol %) complex blended polymer film is better and is acting as the prominent material for lasing applications and development of opto electronic devices. The present blended host polymer matrix doped with 5 mol % Sm3+ ions is a perfect suitable potential material for active reddish orange emission lasing materials for photonic applications and photo electronic devices.

Thermoresponsive Host Polymer Matrix for Self-Healing Luminescent Solar Concentrators

Luminescent solar concentrators (LSCs) are a promising solar energy technology for reducing architectural barriers to the integration of photovoltaic systems into the built environment. In this wor...

Fabrication and characterization of conductive silk fibroin–gold nanocomposite films

This research proposes a one-step fabrication of novel conducting silk fibroin (SF) nanocomposites (NCs) in which in situ generation of nanoparticles from their precursor are achieved. Here, the gold salt (HAuIIICl4·H2O) is reduced to gold nanoparticles (AuNPs) using SF, a renewable natural biopolymer, and SF–AuNPs NCs are developed via solution casting method. The optical absorption spectra recorded using the UV–Visible spectroscopy (UV–Vis) witnesses the generation of anisotropic particles by showing two absorption bands. Also, the calculated optical band gap energy (Eg) value decreases from 4.2 to 2.4 eV with the increasing concentration of AuNPs. The X-ray diffraction (XRD) profile of the NCs confirms the presence of AuNPs. The scanning electron microscopy (SEM) micrographs clearly admit the successful formation of AuNPs in the host polymer matrix with homogeneous dispersion. The size and evolution of the different shaped AuNPs are confirmed by the transmission electron microscopy (TEM) study. An increase in DC conductivity from 1.48 × 10−9 to 7.12 × 10−9 S/cm and decrease in frequency-dependent dielectric constant are observed with the increase in AuNPs. The obtained result suggests that the insulating behaviour of the SF can be effectively changed into a conducting nature with the in situ creation of AuNPs in the SF matrix.

Synthesis of very-fine PbS nanoparticles dispersed homogeneously in MC matrix: effect of concentration on the structural and optical properties of host polymer

Well-dispersed polymer nanocomposite films based on methylcellulose (MC) and lead sulfide (PbS) were prepared by two-step methods; the fine-PbS nanoparticles are first synthesized by in situ chemical reduction method while the films are made by solution casting technique. The effect of different concentration of PbS nanoparticles on the structural, optical properties, surface morphology, and chemical composition of the host polymer matrix were studied by x-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, UV–vis absorption spectroscopy, Scanning electron microscope (SEM), and Energy-dispersive x-ray spectroscopy (EDS) techniques. XRD studies reveal that the synthesized PbS nanoparticles are in cubic nanocrystalline phase with the very-fine grain size distribution between 2.23 to 4.46 nm. The homogeneous distribution of PbS in MC matrix was supported by both UV–vis spectra analysis and SEM images. The UV–vis measurement of nanocomposite films shows high absorption in the visible range, which correlate to the characteristics of the PbS nanoparticles. The effect of various concentration of PbS nanoparticle on the energy band gap of nanocomposite films has been analysed to understand the optimum conditions for the synthesis process. Significant reduction of the direct allowed energy band gap of the MC is observed upon increasing the PbS concentration, from 6.25 eV for pure MC to 1.92 eV for 0.3 M PbS concentration. A linear correlation in the refractive index at infinite frequency with PbS concentration revealed a well-distribution of the dopant throughout the host MC. The analysis of the refractive index was correlated with the results of SEM measurement.

In-line syntactic-foam device for control of water hammer and fluid-borne noise

Water hammer, a common problem in plumbing, is characterized by an impulsive increase in pressure. The pressure rise and associated momentum transfer may cause plumbing noise and vibration, and, potentially, catastrophic plumbing component failures. Water hammer arresters are required in building codes to be proximate to fast-acting valves, such as present in washing machines and other appliances. Commercially available water hammer arresters introduce compliance with a free-piston air spring as the means to limit the peak pressure during water hammer. Syntactic foam, comprising microspheres within a host polymer matrix, may be suitable for application in a water hammer arrester device. Foam-based arresters also enable flow-through designs, which may reduce other fluid-borne noise in addition to controlling water hammer. A prototype flow-through, in-line syntactic water hammer arrester device has been designed and tested. The flow-through design demonstrates adequate performance for service as a water hammer arrester, as well as significant insertion loss against fluid-borne noise.Water hammer, a common problem in plumbing, is characterized by an impulsive increase in pressure. The pressure rise and associated momentum transfer may cause plumbing noise and vibration, and, potentially, catastrophic plumbing component failures. Water hammer arresters are required in building codes to be proximate to fast-acting valves, such as present in washing machines and other appliances. Commercially available water hammer arresters introduce compliance with a free-piston air spring as the means to limit the peak pressure during water hammer. Syntactic foam, comprising microspheres within a host polymer matrix, may be suitable for application in a water hammer arrester device. Foam-based arresters also enable flow-through designs, which may reduce other fluid-borne noise in addition to controlling water hammer. A prototype flow-through, in-line syntactic water hammer arrester device has been designed and tested. The flow-through design demonstrates adequate performance for service as a water ham...

Imine-Rich Poly( o -phenylenediamine) as High-Capacity Trifunctional Organic Electrode for Alkali-Ion Batteries

Alkali-ion batteries, including potassium-ion batteries, lithium-ion batteries, and sodium-ion batteries are important energy storage devices; however, with the cation size increased, there exists ...

Improvement of oxidation resistance of polymer-based nanocomposites through sonication of carbonaceous nanoparticles.

The work aim is focused on two different aspects: first, the investigation of the effect of extended ultra-sound-assisted treatment (us) of carbonaceous nanoparticles, such as carbon nanotubes (CNTs) and carbon black (CB), on their radical scavenging activity, and second, the investigation of the oxidative resistance of polymer-based nanocomposites, containing us-treated CNTs and CB. Particularly, the CNTs and CB have been subjected to us sonication for different time intervals and the performed analysis reveals that both kinds of nanoparticles show decreased average hydrodynamic diameters and large content of surface defects. Really, the increased content of CNTs and CB defects, achieved during the sonication time, leads to an increased reactivity toward 1,1-diphenyl-2-pycryl (DPPH) radicals and an enhanced anti-oxidant activity toward macro-radicals, coming from the photo-degradation of the host polymer matrix. The studies of photo-oxidative behavior of the nanocomposites, based on Ultra High Molecular Weight (UHMWPE), reveal that the us treatment of the nanoparticles has a benefic effect on the oxidative resistance of the nanocomposites, especially at long exposure times. Overall, the ultra-sound-assisted treatment can be considered twofold powerful tool: (i) for disruption of the nanoparticles aggregations, and (ii) for capitalization of surface defects, amplifying and tuning in a controlled way the radical scavenging activity of the carbonaceous nanoparticles.

Photo-induced inter-chain and interfacial charge transfer in Cu–ZnO/ poly (3-octylthiophene) hybrid nanocomposites

Poly (3-octylthiophene) conducting polymer and Cu-doped zinc oxide hybrid nanocomposites films were prepared by using ultrasonication cast technique. The films were characterized using various characterization techniques for their structral, vibrational, morphological, and optical properties. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) investigations suggest the presence of ZnO nanoparticles in the polymer host matrix. FTIR measurements also confirm the presence of various functional groups in the thiophene ring of poly (3-octylthipohene) polymer as well as in its nanocomposites. The UV–visible absorption spectra of polymer films exhibit the broad range absorption covering the almost whole visible region and attributed to the generation of a high density of photo-induced charge carrier by the absorption of incident photons. This is an inherent process of the polymer that appears during the absorption of the incident photons leading to the separation of bound polaron pairs that present on adjacent polymer chains as a result of inter-chain charge transfer. However, broadening in the absorption spectra of polymer is observed by incorporating Cu–ZnO nanoparticles into the polymer host matrix. This is attributed to the fact that inter-chain as well as interfacial charge transfer are responsible for photo-induced charge carriers generation; and thus it increases upon increasing in the weight percentage of nanoparticles in the polymer host matrix. The processes of inter-chain and interfacial charge transfer are well explained by developing a schematic charge transfer diagram. Furthermore, the PL emission spectra of polymer film exhibit the characteristic peaks related to the aromatic benzene ring and formed chains between the benzene ring with quinone segments of polymer. However, the PL spectra of hybrid nanocomposites film show a dramatic decrease in the intensity of emission leading the quenching effect and attributed to the high recombination rate of generated charge carriers through the Cu–ZnO induced extrinsic non-radiative recombination centers such as trap and defects. Thus, poly (3-octylthiophene) and its hybrid nanocomposite films could be considered as potential material for solar cells, diode, light emitting diodes, and resistive switching memory devices.

Vapour deposited nanocomposite films of perylene bis azo-imides with improved photoresponsiveness by visible light

The paper presents preparation of nanocomposite thin films of three newly synthesized perylene bis azo-imides in polyimide matrix by vapour deposition, results of DFT quantum chemical calculations on the optimized molecular geometry of trans (E) and cis (Z) isomers of the studied dyes as well as photoinduced birefringence measurements to explore potential optical application of these novel materials. Vapour deposited single films of the dyes were studied by reflectance UV-VIS and fluorescence spectroscopy in order to investigate the nature of electron transitions and donor-acceptor interactions between phenylazo fragments and perylene core. The nanocomposite films were prepared through vapour deposition of ODA (4,4′-oxydianiline) and PMDA (pyromellitic dianhydride) as the host polymer matrix and of corresponding perylene bis azo-imide dyes as “guest” at two various concentrations 5 % and 10 % w/w. It was found that nanocomposite films have improved photoresponsivness by applying visible light at λ = 532 nm compared to the single deposited films of dyes. This study shows the applicability of the synthesized dyes embedded in the polyimide matrix as visible-light activated molecular switches.

Structural, morphological and electrical studies of poly (1, 8-diaminonaphthalene)/CdSe(S) nanocomposites for charge storage applications

The world is facing challenges of energy shortage and it requires innovations in energy storage devices that needs be more efficient and economically viable. Addressing these issues, in the present work poly (1, 8-diaminonaphthalene/CdSe(S) nanocomposites were synthesized following an economic chemical oxidative polymerization method. The Fourier transform infrared (FTIR) spectra confirmed the presence of CdSe in the poly (1, 8-diaminonaphthalene) (PDAN) matrix. The crystallite size in PDAN/CdSe nanocomposites was calculated from x-ray diffraction (XRD) spectra and it was found to be of the order of 4 nm. The lattice constant was also calculated from XRD analysis and it was calculated to be 5 Å which agrees well with that of the CdSe. Field emission scanning electron microscope (FESEM) images showed homogenous dispersion of spherical particles in the host polymer matrix. It ensured the presence of PDAN and agglomerated CdSe quantum dots (QDs) in the PDAN matrix. Impedance data were analyzed by fitting an electrical equivalent circuit based on Randle’s model. When PDAN was subjected to form nanocomposites with the CdSe, there was a decrease in the dielectric constant and an increase in the dielectric loss due to alignment of polarization charges with frequency. The results indicate that the mechanism of alignment of charge carriers with frequency could be helpful in increasing the charge storage capacity of the material. Thus due to low loss at lower and at higher frequencies in the nanocomposites, the nanocomposites of PDAN/CdSe have potential to be used at these frequencies in charge storage applications in electronic industry.

The novel synthesis and luminescence studies of CuO and Fe2 O3 embedded(8-hydroxyquinoline)zinc nanocomposites

The present study investigates the synthesis of novel luminescent polymer nanocomposite through the incorporation of CuO and Fe2 O3 into a C18 H12 N2 O2 Zn host polymer matrix. The observed green electroluminescence behavior originates mainly from the shift in the HOMO-LUMO energy gap of the polymer matrix caused by the inclusion of oxidized metal/oxygen ions from the incorporated metal oxides into the pyridyl and phenyl groups of the host polymer. The existence of oxidized metal/oxygen ionic states in the polymer matrix is successfully confirmed through X-ray photoelectron spectroscopic analysis. The FTIR analysis is utilized to verify the presence of pyridyl and phenyl groups in the host polymer matrix. The successful incorporation of CuO and Fe2 O3 into the host polymer matrix is examined through FESEM and HRTEM analyses. XRD, EDS, and XPS analyses are employed in order to confirm the exact crystalline phase and material compositions of the samples prepared.

Reducing the Rate of Plasticizer Leaching from Poly(vinyl chloride) Matrix

Abstract—The effects that the protective coating based on azidized poly(vinyl chloride) has on the leaching kinetics of dioctyl phthalate from the host polymer matrix are evaluated. The barrier properties of the applied protective coatings vary with the stirring time of the coating mixture. We develop models for forecasting the effects that the stirring time has on the leaching kinetics at the first stage of leaching and for identifying the conditions initiating the second stage, which is characterized by slower leaching rates. The mechanism underlying dioctyl phthalate leaching from poly(vinyl chloride) films with protective coating is discussed.

Role of Chemical Adatoms in Fracture Mechanics of Graphene Nanolayer

Functionalized graphene’s exceptional compatibility and interfacial interaction with host polymer matrix were the motivating features for their fracture description. The authors have considered hydroxyl, epoxide and carboxyl functional groups for this examination; as our main area was to grasp the molecular physics behind their adsorption in graphene lattice. These oxygen variants of graphene form the backbone of intrinsic atomic structure of graphene oxide (GO). Molecular dynamics (MD) simulations in combination with reactive force field (ReaxFF) have been executed to perceive the failure mechanisms in GO framework. Since the literature does not provide an extensively acknowledged model for GO structure, its fracture toughness values are also untold. The authors have tried to correct this gap and forecasted a range of fracture toughness numerical value of 1.6 ± 0.25 MPa m-1/2 by examining their various configurations.

Mechanistic insight into the improved Li ion conductivity of solid polymer electrolytes.

Polymer based solid electrolytes (SEs) are envisaged as futuristic components of safer solid state energy devices. But the semi-crystalline nature and slow dynamics of the host polymer matrix are found to hamper the ion transport through the solid polymer network and hence solid state devices are still far beyond the scope of practical application. In this study, we unravel the synergistic roles of Li salt (LiClO4) and two different polymers – polyethylene oxide (PEO) and polydimethyl siloxane (PDMS), in the Li ion transport through their solid blend based electrolyte. A detailed study using dielectric spectroscopy and thermo-mechanical analysis is conducted to understand the tunability of the PEO chain dynamics with LiClO4 and the mechanism of hopping of Li ions by forming ion pairs with oxygen dipoles on the PEO backbone is established. Despite the lack of PDMS's capability to solvate ions and promote ion transport directly, its proper mixing within the PEO host matrix is demonstrated to enhance ion transport due to the influence of PDMS on the segmental dynamics of PEO. A detailed molecular dynamics study supported by experimental validation suggests that even inert polymers can affect the dynamics of the active host matrix and increase ion transport, leading to next generation high ionic conductivity solid matrices, and opens new avenues in designing polymer based transparent electrolytes.

Polymer morphology and interfacial charge transfer dominate over energy-dependent scattering in organic-inorganic thermoelectrics

Hybrid (organic-inorganic) materials have emerged as a promising class of thermoelectric materials, achieving power factors (S2σ) exceeding those of either constituent. The mechanism of this enhancement is still under debate, and pinpointing the underlying physics has proven difficult. In this work, we combine transport measurements with theoretical simulations and first principles calculations on a prototypical PEDOT:PSS-Te(Cux) nanowire hybrid material system to understand the effect of templating and charge redistribution on the thermoelectric performance. Further, we apply the recently developed Kang-Snyder charge transport model to show that scattering of holes in the hybrid system, defined by the energy-dependent scattering parameter, remains the same as in the host polymer matrix; performance is instead dictated by polymer morphology manifested in an energy-independent transport coefficient. We build upon this language to explain thermoelectric behavior in a variety of PEDOT and P3HT based hybrids acting as a guide for future work in multiphase materials.

Aromatic thermosetting copolyester bionanocomposites as reconfigurable bone substitute materials: Interfacial interactions between reinforcement particles and polymer network

Development of porous materials consisting of polymer host matrix enriched with bioactive ceramic particles that can initiate the reproduction of cellular organisms while maintaining in vivo mechanical reliability is a long-standing challenge for synthetic bone substitutes. We present hydroxyapatite (HA) reinforced aromatic thermosetting copolyester (ATSP) matrix bionanocomposite as a potential reconfigurable bone replacement material. The nanocomposite is fabricated by solid-state mixing a matching set of precursor oligomers with biocompatible pristine HA particles. During endothermic condensation polymerization reaction, the constituent oligomers form a mechanochemically robust crosslinked aromatic backbone while incorporating the HAs into a self-generated cellular structure. The morphological analysis demonstrates near-homogenous distributions of the pristine HAs within the matrix. The HAs behave as a crack-arrester which promotes a more deformation-tolerant formation with relatively enhanced material toughness. Chain relaxation dynamics of the nanocomposite matrix during glass transition is modified via HA-induced segmental immobilization. Chemical characterization of the polymer backbone composition reveals the presence of a hydrogen-advanced covalent interfacial coupling mechanism between the HAs and ATSP matrix. This report lays the groundwork for further studies on aromatic thermosetting copolyester matrix bionanocomposites which may find applications in various artificial bone needs.

Glass transition broadening via nanofiller‐contiguous polymer network in aromatic thermosetting copolyester nanocomposites

ABSTRACTThe glass transition is a genuine imprint of temperature‐dependent structural relaxation dynamics of backbone chains in amorphous polymers, which can also reflect features of chemical transformations induced in macromolecular architectures. Optimization of thermophysical properties of polymer nanocomposites beyond the state of the art is contingent on strong interfacial bonding between nanofiller particles and host polymer matrix chains that accordingly modifies glass transition characteristics. Contemporary polymer nanocomposite configurations have demonstrated only marginal glass transition temperature shifts utilizing conventional polymer matrix and functionalized nanofiller combinations. We present nanofiller‐contiguous polymer network with aromatic thermosetting copolyester nanocomposites in which carbon nanofillers covalently conjugate with cure advancing crosslinked backbone chains through functional end‐groups of constituent precursor oligomers upon an in situ polymerization reaction. Via thoroughly transformed backbone chain configuration, the polymer nanocomposites demonstrate unprecedented glass transition peak broadening by about 100 °C along with significant temperature upshift of around 80 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1595–1603

Synthesis and emissive properties of a series of tetrahydro (imidazo[1,5-a]pyrid-3-yl)phenols: a new class of large Stokes shift organic dyes

A series of 2-(5,6,7,8-tetrahydroimidazo[1,5-a]pyridin-3-yl)phenols with different substituents (R) in the para position with respect to the hydroxyl group, was synthesized. The photophysical properties of these species have been investigated in dichloromethane solution: they displayed intense fluorescence when excited with UV light (310–340 nm), with λmax of emission varying in the range 430–530 nm and lifetime decay of few nanoseconds. A very large Stokes shift (up to 189 nm) and high absolute quantum yields (up to 0.72) were recorded for most of the compounds. Moreover, good tuning of the emission is observed according to the electronic features of the substituent R, and a linear correlation was found between the emission maxima of the compounds and the Hammett σp constants of R. Two of these (tetrahydroimidazo[1,5-a]pyridin-3-yl)phenols were then chosen for preliminary measurements of their photophysical properties when dispersed in a host polymeric matrix (PMMA).