Host Polymer Research Articles

Morphological, structural, optical, broadband frequency range dielectric and electrical properties of PVDF/PMMA/BaTiO3 nanocomposites for futuristic microelectronic and optoelectronic technologies

Polymer blend nanocomposite (PBNC) films consisted of fluoropolymer poly(vinylidene fluoride) (PVDF) and plexiglass polymer poly(methyl methacrylate) (PMMA) blend host matrix (fixed composition blend of PVDF/PMMA = 80/20 wt/wt%) with barium titanate (BaTiO3) ceramic nanofiller of varying concentrations (x = 0, 2.5, 5, 10, and 15 wt%) were prepared via a state-of-the-art solution-cast method. Scanning electron microscope (SEM) images evidenced high homogeneity of these PBNC films and a huge alteration in the spherulite morphology of the PVDF with the increase in dispersed BaTiO3 concentration in the polymer blend matrix. The X-ray diffraction (XRD) patterns identified the presence of electro-active polar β- and γ-phases of the PVDF crystallites in all the composite materials which are supported by the results of Fourier transform infrared (FTIR) spectra. The differential scanning calorimeter (DSC) thermograms explained the high melting temperature of these overlapped PVDF polymorphs and the degree of crystallinity altered anomalously with the variation of nanofiller concentration. The absorbance of ultraviolet-visible (UV-Vis) radiations enhanced while the direct energy band gap of the 80PVDF/20PMMA blend matrix and also the semiconducting BaTiO3 was found to decrease with the increased concentration of nanomaterial in the host polymer matrix. The ambient temperature broadband dielectric spectra covering the frequency range from 20 Hz to 1 GHz explain that the real part of complex dielectric permittivity reduced with a huge dispersion at higher radio frequencies where the dielectric loss tangent and electric modulus spectra exhibited an intense chain segmental relaxation process. The electrical conductivity of these PBNC films increased with frequency augmented and illustrated a small variation for different concentration composites. The experimental results demonstrated that these PVDF/PMMA/BaTiO3 films could be potential candidates for frequency tunable nanodielectric, electromagnetic interference shielders, a flexible dielectric substrate, thermal insulators, and bandgap regulated materials for futuristic microelectronic, capacitive energy storage, and optoelectronic technologies.

Role of Carbonyl Distortions Facilitating Persistent Room-Temperature Phosphorescence

A decrease in the room-temperature phosphorescence (RTP) yield and RTP lifetime with increasing temperature is often explained by the increased nonradiative transition from the lowest triplet excited state (T1) caused by molecular vibrations of the chromophores. Here, we report a positive contribution of molecular vibrations and the distortion of vanillic acid (VA) dispersed in amorphous insulating polymer hosts to phosphorescence characteristics. We investigated triplet generation as well as photophysical processes from T1 of VA dispersed in poly(methyl methacrylate) (PMMA) and poly(vinyl alcohol) (PVA). Comparisons between optically measured data and calculation-based data, regarding the phosphoresce rate (kp) and the rate constant of the nonradiative transition (knr) from T1, reveal that kp and knr of the dispersed VA negligibly changed in PMMA or PVA, indicating that intermolecular processes between VA and PMMA are related to a large RTP quenching of VA in PMMA. Vibrational out-of-plane distortion of the carbonyl moiety of VA induced ππ*–nπ* mixing between the high-order singlet excited state and the ground state, mainly enhancing kp compared with knr of VA. Although vibrations are often reported to quench RTP, this report suggests that some distortions induced by vibrations of other chromophores contribute to RTP enhancement of molecular solid materials.

Utilization of host assisted aggregation-induced emission of ANS dye for ATP sensing

Photoemission efficiency of certain organic dyes gets augmented many fold when they are aggregated in solution. This AIE (Aggregation induced emission) property of dyes opens up new horizon in bio-imaging, fluorescence sensing of bio-analytes, molecular electronics, optoelectronics, chemical sensor etc. Herein, we report AIE enhancement of anionic ANS dye (8-anilinonaphthalene-1-sulfonic acid) aided by multi-cationic polymeric host, PAMA [poly(diallyl dimethyl ammonium) chloride] in aqueous solution. Anionic ANS loses its negative charge partially through charge neutralization at the vicinity of poly cationic PAMA host, leading to the reduction of like charge repulsion between the ANS molecules. This helps the dye molecules to stick together by π-π interaction, forming an aggregated assembly. Hence, there is a substantial reduction in torsional motion of the dye molecules, which is ultimately expressed as significant enhancement in its fluorescence intensity. The interaction of ANS dye with host polymer PAMA is primarily electrostatic in nature as indicated by ionic strength dependent study. This prompted the ANS-PAMA complex to be used as fluorescence probe to detect and quantify an important charged bio-analyte ATP (Adenosine triphosphate) in serum matrix at physiological pH 7.2, exhibiting the applicability of the studied system in the field of bio-sensing.

High‐Performance Dual‐Salt Plastic Crystal Electrolyte Enabled by Succinonitrile‐Regulated Porous Polymer Host

AbstractSuccinonitrile (SN)‐based plastic crystal electrolytes (PCE) show great promise for solid‐state lithium‐metal batteries (LMBs) because of their outstanding electrochemical properties. However, limited by the low mechanical strength of SN, SN‐based PCEs are difficult to act as an independent self‐supporting electrolyte films, which seriously restricts their practical application. In this study, a SN‐regulated poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) porous host is proposed via a facile phase separation method as a promising strategy for addressing this issue, which enables a high‐performance dual‐salt SN‐based PCE (named as DPCE). The as‐prepared host simultaneously provides homogeneous porous network and robust mechanical support, which is convenient to accommodate DPCE evenly and increases the strength of DPCE to restrict dendrites growth. As a result, with this efficient host, the Li symmetric cell assembled with DPCE shows superior long‐term stability for >1200 h at a current density of 0.1 mA cm−2. Moreover, the assembled Li|LiFePO4 cell delivers a high‐capacity retention of 99.3% after 700 cycles under 2 C at room temperature, demonstrating the promising potential for developing high‐performance solid‐state LMBs.

Electrical and Structural Properties of PEMA‐Based Plasticized Polymer Electrolyte

AbstractTo resolve the challenges that portable devices confront, polymer electrolytes should be developed. Polymer electrolytes have a number of advantages, including nonflammability, low cost, high stability, no leakage, and a long lifespan. In the present research work, PEMA host polymer with potassium iodide salt enclosure is used with ethylene carbonate (EC) plasticizer to enhance mechanical strength and ionic conductivity. The PEMA+40% wt Kl sample conductivity is measured by complex impedance spectroscopy technique and the maximum conductivity obtained is 3.80×10−6 S cm‐1 at room temperature. When EC is added into the solution, there is an increase in conductivity, and the maximum conductivity measured is 4.65×10−5 S cm‐1 with sample PEMA+40% wt KI+ %60 wt EC. The prepared electrolyte structural changes and complex formation are subjected to FTIR and XRD characterization techniques. The pore nature of the synthesized polymer electrolyte is investigated using surface electron microscopy.

Humidity Effect on Ionic Conductivity of Composite Polymer Electrolytes

AbstractThe solid polymer electrolytes (SPE) based electrochemical devices are an area of attention for more than two decades. The ability of thin‐film preparation and leakage proof over the liquid counterpart are the key factors of SPE. In the present work, two different compositions, 80–20 and 85–15, of PVA:KI has been used as a host polymer complex. Where further 10 wt% of p‐Si dispersed with PVA:KI complexes. Polymer films have been prepared with standard solution cast techniques, which are further characterized for their electrical conductivity by Electrical Impedance Spectroscopy (EIS). Also, the humidity effect on the ionic conductivity of these thin films is calculated. It is observed that the ionic conductivity of these polymer electrolytes films increases with 58%, 74%, and 89% humidity. To understand the change in this ionic conductivity, the concentration and mobility of ions are also calculated, and it is found that the change in conductivity are predominately influenced due to the mobility of charge carriers.

Modified Poly(Vinyl Alcohol) Based Polymer Electrolyte for Dye Sensitized Solar Cells (DSSCs)

AbstractDue to increasing energy demand day by day, it must be necessary to have an alternate source of energy beside natural resources. Sun is the ultimate source of solar energy. So, from this solar energy, various types of solar cells are fabricated easily which are available in markets but these are somewhat costly. So, there is requirement of a low‐cost alternative to costly crystalline solar cells, which is fulfilled by dye sensitized solar cell (DSSC). Due to many potential properties like good ionic conductivity, thin film forming ability and many more, polymer electrolyte plays a vital role in improving the efficiency of DSSC which cannot be obtained by using volatile liquid electrolytes which are used earlier. The reliance of DSSCs on liquid electrolytes imposes a limit and restriction on the manufacture of DSSC modules. Liquid electrolyte faces many problems like corrosion, leakage, and evaporation. When the photoanode comes into touch with the volatilized redox‐electrolytes solution, the charge distribution at the semiconductor–electrolyte interface changes, resulting in photo corrosion on the photoelectrode. Furthermore, electron recombination at semiconductor–liquid electrolytes interfaces is discovered to cause performance losses. The concept of ionic conductivity observed in polymer materials when complexed with salt is a significant step forward in the development of DSSC devices.In this review, the fabrication of DSSC using polymer electrolyte, specifically PVA based solid polymer electrolyte is discussed. Here solid polymer electrolytes are of special interest due to thin film forming ability and overall good performance. Due to inherent properties like cost‐effectiveness, better tensile strength, and high hydrophilicity, PVA is chosen as a novel applicant for host polymer. The recent advancement of DSSC using modified PVA polymer electrolyte by incorporation of nanosized fillers, plasticizers, polymer blend, by the formation of conducting polymer electrolyte are discussed in detail. The improvement in ionic conductivity and enhanced efficiency of DSSC by using above mentioned factors are also discussed.

Novel polymer electrolyte based polyurethane acrylate for low-cost perovskite solar cells applications

Gel polymer electrolytes with polyurethane acrylate (PUA) and tetrapropylammonium iodide (TPAI) have been prepared. The maximum conductivity of (4.95 ± 0.02)×10−5 S cm−1 was obtained after 35 wt.% TPAI is added to PUA (G5 electrolyte), dominated by the highest charge carrier mobility (µ). The perovskite solar cell (PSC) with G5 electrolyte displayed the highest power conversion efficiency of (0.206 ± 0.014)%, caused by the highest µ in electrolyte G5 that accelerates the electron transfer from the counter electrode to the ionized perovskite. This research proves that PUA can be exploited as a host polymer in polymer electrolytes for PSC applications.

Limiting Factors Affecting the Ionic Conductivities of LATP/Polymer Hybrid Electrolytes

All-Solid-State Lithium Batteries (ASSLB) are promising candidates for next generation lithium battery systems due to their increased safety, stability, and energy density. Ceramic and solid composite electrolytes (SCE), which consist of dispersed ceramic particles within a polymeric host, are among the preferred technologies for use as electrolytes in ASSLB systems. Synergetic effects between ceramic and polymer electrolyte components are usually reported in SCE. Herein, we report a case study on the lithium conductivity of ceramic and SCE comprised of Li1.4Al0.4Ti1.6(PO4)3 (LATP), a NASICON-type ceramic. An evaluation of the impact of the processing and sintering of the ceramic on the conductive properties of the electrolyte is addressed. The study is then extended to Poly(Ethylene) Oxide (PEO)-LATP SCE. The presence of the ceramic particles conferred limited benefits to the SCE. These findings somewhat contradict commonly held assumptions on the role of ceramic additives in SCE.

Multistep sequence-controlled supramolecular polymerization by the combination of multiple self-assembly motifs

The precise sequence control of polymer chain is an important research topic of polymer chemistry. Although some methods such as iterative synthesis and supramolecular polymerization have been developed to fabricate sequence-controllable polymer, it is still a great challenge to consecutively prepare multiple supramolecular polymers with different sequence structures. In this work, through the reasonable utilization of assembly motifs, we integrated multiple host-guest recognitions and metal coordination interactions to prepare different sequence-controlled supramolecular polymers by a multistep assembly strategy. This research provides inspiration for the design and preparation of supramolecular polymers with different sequence structures.

Triboelectric Charging Behaviors of Polyester Films Doped with Titanium Dioxide Nanoparticles of Various Crystal Structures

It is empirically known that titanium dioxide nanoparticles stabilize the contact and frictional charge of the host polymers to which they are added. However, the mechanism for the stabilization process has not yet been elucidated. In this study, polyester films doped with titanium dioxide nanoparticles of different crystalline forms were triboelectrically charged and the effect of humidity on their charging characteristics was subsequently investigated to elucidate the charge stabilization mechanism. Our first finding was that the rutile-, rutile–anatase mixed crystal (P25)-, and amorphous-dominant-type titanium dioxide nanoparticles reduced the sensitivity of the films to humidity (humidity dependence), while the anatase-type titanium dioxide enhanced the humidity dependence. This difference in action was explained by associating it with the different water adsorption forms on the major crystalline surface of each titanium dioxide type. The second finding was that doping with titanium dioxide nanoparticles, particularly rutile and P25 nanoparticles, reduced fluctuations in the amount of tribocharges of the polyester film. This crystalline-form-dependent difference in action was considered to be based on the depth of the electron traps involved in each titanium dioxide type. The above two findings have allowed us to propose the first mechanism of tribocharge stabilization by titanium dioxide.

Rationally Constructed De Novo Fluorescent Nanosensor for Nitric Oxide Detection and Imaging in Living Cells and Inflammatory Mice Models.

For the early diagnosis and effective evaluation of treatment effects of inflammation, a de novo bioanalytical method is urgently needed to monitor the metabolite nitric oxide (NO) associated with inflammatory diseases. However, developing a reliable detection method with excellent water solubility, biocompatibility, long retention time, and blood circulation is still challenging. In this work, we reported for the first time a de novo host-guest self-assembled nanosensor CTA for the quantitative detection and visualization of NO levels in inflammatory models. CTA mainly consists of two parts: (i) an adamantyl-labeled guest small-molecule RN-adH containing a classical response moiety o-phenylenediamine for a chemical-specific response toward NO and fluorophore rhodamine B with excellent optical properties as an internal reference for self-calibration and (ii) a remarkable water-soluble and biocompatible supramolecular β-cyclodextrin polymer (Poly-β-CD) host. In the presence of NO, the o-phenylenediamine unit was reacted with NO at a low pH value of ∼7.0, accompanied by changes in the intensity of the two emission peaks corrected for each other and the change in fluorescence color of the CTA solution from fuchsia to pink. Furthermore, CTA was an effective tool for NO detection with a fast response time (∼60 s), high selectivity, and sensitivity (LOD: 22.3 nM). Impressively, the CTA nanosensor has successfully achieved the targeted imaging of NO in living inflammatory RAW 264.7 cells and mice models with satisfactory results, which can provide a powerful molecular tool for the visualization and assessment of the occurrence and development of NO-related inflammatory diseases in complex biosystems.

Luminescent Polymer Composites for Optical Fiber Sensors.

Optical fiber sensors incorporating luminescent materials are useful for detecting physical parameters and biochemical species. Fluorescent materials integrated on the tips of optical fibers, for example, provide a means to perform fluorescence thermometry while monitoring the intensity or the spectral variations of the fluorescence signal. Similarly, certain molecules can be tracked by monitoring their characteristic emission in the UV wavelength range. A key element for these sensing approaches is the luminescent composite, which may be obtained upon allocating luminescent nanomaterials in glass or polymer hosts. In this work, we explore the fluorescence features of two composites incorporating lanthanide-doped fluorescent powders using polydimethylsiloxane (PDMS) as a host. The composites are obtained by a simple mixing procedure and can be subsequently deposited onto the end faces of optical fibers via dip coating or molding. Whereas one of the composites has shown to be useful for the fabrication of fiber optic temperature sensors, the other shows promising result for detection of UV radiation. The performance of both composites is first evaluated for the fabrication of membranes by examining features such as fluorescent stability. We further explore the influence of parameters such as particle concentration and density on the fluorescence features of the polymer blends. Finally, we demonstrate the incorporation of these PDMS fluorescent composites onto optical fibers and evaluate their sensing capabilities.

Real‐Time Probing and Unraveling the Morphology Formation of Blade‐Coated Ternary Nonfullerene Organic Photovoltaics with In Situ X‐Ray Scattering

AbstractCharacterizing the bulk heterojunction (BHJ) morphology of the active layer is essential for optimizing blade‐coated organic solar cells (OSCs). Here, the morphology evolution of a highly efficient ternary polymer:nonfullerene blend PM6:N3:N2200 under different blade coating conditions is probed in real‐time by in situ synchrotron X‐ray scattering and in situ ultraviolet‐visible (UV‐vis) spectroscopy. Besides, the morphology of blade‐coated blend films at different conditions is detailed by ex situ X‐ray scattering and microscopic imaging. The ternary blend film exhibited optimized morphology, such as superior molecular stacking structure and appropriate phase separation structure, and boosted photovoltaic performance of the binary blend, as adding a second polymer component to the host polymer:nonfullerene system can balance nucleation and crystallization of polymers and small molecules, facilitating molecular rearrangement to perfect crystallization. Both binary and ternary blends obtained optimized morphology and photovoltaic properties at medium coating speed, mainly attributed to the movement of the polymer and small molecules at the long crystallization and aggregation stage. These findings help understand morphology formation under film drying and provide guidance for optimizing the morphology in blade‐coated OSCs.

Evolving Role of Ca2+ on the Long-Term Phosphate Adsorption-Regeneration Performance of Nanoconfined Hydrated Lanthanum Oxides: Short-Term Enhancement and Long-Term Inhibition

Phosphorus (P) advanced treatment by adsorption reduces the risk of eutrophication in natural waters and reservoirs. The impact of ubiquitous Ca2+ on long-term P removal is critical in assessing the regeneration efficiency of one adsorbent, which is a vital indicator for cost-effectiveness. Given the critical role of lanthanum (La)-based composite materials in P removal, in this study, we unravel the long-term evolving role of Ca2+ on phosphate removal by nanosized hydrated lanthanum oxides (HLO) confined in cross-linked polystyrene beads (HLO@201) over 20 adsorption-regeneration cycles and fixed-bed column runs, with a combination of macroscopic adsorption experiments, microscopic structural investigation, and theoretical calculations. The role of Ca2+ gradually evolves from positive (5–70% higher than Ca2+-free group) to negative (18–41% lower than the Ca2+-free group) with ongoing cyclic runs of HLO@201, which is distinctive from the bulky HLO. The presence of Ca2+ enhances P uptake by HLO@201 possibly through ≡La–P–Ca–P multiple complexation and Ca–P precipitation (i.e., hydroxyapatite, HAP) inside the polymeric host, which creates an antagonistic effect with HLO over time. The formed Ca–P precipitates may accumulate and encapsulate on the surface of HLO nanoparticles, which induce the formation of irreversible LaPO4·xH2O under nanoconfinement that deplete the active adsorptive sites. A two-step (acid wash + NaOH) regeneration method can partially recover the P removal performance of HLO@201. We envision that this study could be a cautionary tale for advanced treatment of P by adsorption, to inspire re-evaluation on the long-term performance of adsorption processes.

Quantum Molecular Descriptors of 6-Thioguanine Adsorbed PPy-PNVK Conducting Polymer: A DFT Analysis

6-Thioguanine (6-TG) is an important drug to cure cancer with fierce adverse effects on human being, necessitating its frequent monitoring. Present work reports the computational analysis of a copolymer (PPy-PNVK), synthesized using polypyrrole (PPy) and poly(9-vinyl carbazole) (PNVK) host polymers. The sensing ability of these polymers for 6-TG, has been performed through the DFT formulated ab initio approach employing the generalized gradient approximations (GGA), considering the revised-Perdew, Burke and Ernzerh (rPBE) pattern of parameters. The suitability of these polymers for 6-TG sensing application, has been assessed by analyzing the variations in the HOMO-LUMO gaps, density of state (DOS), Mulliken population, molecular energy spectrum (MES), adsorption energy (Eads), bond variation, chemical reactivity of the surface, the recovery time (τ) and the electron density plots. The estimated negative adsorption energy confirms the physisorption and stability of 6-TG on PPy, PNVK and their copolymer counterpart. Considering the recovery time, range of detection, reusability and quantum molecular descriptors as an important sensing parameters, it has been observed that the computationally synthesized copolymer is relatively better in comparison to its host polymers.

Microscopic temperature-dependent structural dynamics in polymer nanocomposites: role of the graft-matrix chain interfacial entropic effect.

We present a systematic study of the structural dynamics in bulk entropic polymer nanocomposites (PNCs) with deuterated-polymer-grafted nanoparticles (DPGNPs) using quasi-elastic neutron scattering (QENS). We observe that the wave-vector-dependent relaxation dynamics depend on the entropic parameter f as well as the length scale being probed. The entropic parameter can be defined in terms of the grafted-to-matrix polymer molecular weight ratio and controls the extent of matrix chain penetration into the graft. Dynamical cross-over from Gaussian to non-Gaussian behavior at the wave vector Qc, which depends on temperature and f, was observed. Further insight into the underlying microscopic mechanism responsible for the observed behavior revealed that when interpreted using a jump-diffusion model, in addition to the speeding-up in local chain dynamics, the elementary distance over which sections of the chain hop is strongly dependent on f. Interestingly, we also observe dynamic heterogeneity (DH) in the studied systems, characterized by the non-Gaussian parameter α2, which reduces for a high-f (f = 0.225) sample compared with the pristine host polymer, indicating reduced dynamical heterogeneity, while it is mostly unchanged for the low-f sample. The results highlight that, unlike enthalpic PNCs, entropic PNCs with DPGNPs can modify the host polymer dynamics due to the subtle balance of interactions that occur at different length scales in the matrix.

Energy transfer between molecules from core to shell in one-dimensional coaxial electrospun nanofibres

FRET from the core to the shell of a coaxial nanofibre structure was explored. BODIPY was embedded in the core and rhodamine in the shell (B-PVP@Rh-PVP) with PVP as the host polymer. Upon excitation of BODIPY, emission of rhodamine was observed.

Preparation, characterization and electrical properties of 80 PEO − 20 PVdF: x NaNO3 complexed polymer electrolyte systems

PEO (Polyethylene Oxide) and PVdF (Polyvinylidene Fluoride) based Coplexed Solid Polymer Electrolytes (CSPEs) have been prepared using solution casting method with different weight percentages of NaNO3 (Sodium Nitrate). DMF (Dimethyl Formamide) was used as common solvent. The prepared systems are characterized by XRD (X-Ray Diffraction), SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) and DSC (Differential Scanning Calorimetry) to investigate the crystal structure, surface morphology, vibrational modes, and melting points respectively. Impedance spectroscopy is used to investigate the electrical, dielectric, and electric modulus properties of CSPE systems between temperatures of 298 K and 348 K in the frequency range of 100 Hz to 10 MHz. The ionic conductivity of polymer systems is found to increase with temperature. The maximum enhancement in conductivity (9.334x10-5 S cm−1) is observed for 5 wt% salt system, which is attributed to decrease in crystallanity and increase in the concentration of defects in space charge region formed between the host polymer and salt. Ion transport number has been calculated by using Wagner's polarization method and the maximum (0.89) is noticed for PPN-5 system.

Optical properties of multi-layers structured PEO/PVP solid polymer membranes doped with sodium perchlorate

In this present research work, fabrication of multi-layers structured (MLS) polymer membranes has been proposed to understand the variation of the optical bandgap and determine the types of electronic transitions as a function of sodium salt doping concentration. Solid MLS polymer membranes based on PEO/PVP have been prepared by the well-known solution cast technique. The recorded absorption, transmittance and reflectance spectra revealed that, incident energy absorption increased upon increase of salt dopant concentration and a shift of absorption edge towards lower energy region suggests the good complexation between the host polymers and dissociated salt (Na+, ClO4-) ions, which in turn the energy bandgap decrement expected. A detailed investigation has been carried out on the variation of refractive index of all the MLS polymer membranes as a function of salt doping concentration. The miscibility between the sodium salt and the individual polymers present in MLS polymer membranes can be understood from the linear relationship between the refractive index and the volume fraction of the added salt. The increase of extinction coefficient at high wavelengths was observed. The optical band gap measured from the plots of (αhυ)x versus photon energy (hυ) was compared to that determined from the optical dielectric loss.