Properties and Structure of Thermoplastic Polyvinyl Alcohol/Polyamide Sea-Island Fibers

Ultra-fine fibers derived from sea-island fibers have attracted great attention due to their excellent overall performance. However, green and efficient splitting of sea-island fibers is still a challenging task. In this work, thermoplastic polyvinyl alcohol (TPVA) was prepared by the physical blending of plasticizer. The modified TPVA showed a high decomposition temperature (285 °C) and a wide thermoplastic processing window. This made TPVA match well with polyamide 6 (PA6) to form conjugated melts at 250 °C. Corresponding PVA/PA6 sea-island fibers were first reported to realize water-splitting instead of alkali-extraction of "sea" polymers. The effects of sea/island mass ratios and different spinning speeds on the properties of PVA/PA6 sea-island pre-oriented yarn (POY) were investigated. A higher spinning speed enhanced the orientation-induced crystalline behavior of fiber, therefore increasing the tensile strength of fibers. As the increase of spinning speed from 1000 to 1500 m/min, the crystalline degree of corresponding POYs increased from 9.9 to 14.3%. The plasticizer in PVA did not diffuse to the PA matrix during spinning. However, PVA could induce the crystallization of PA6 via interfacial hydrogen bonding. When the spinning speed was 1500 m/min, and PVA/PA6 was 7:3, the tensile strength reached the highest value of 1.67 cN/dtex. The uniform diameters of ultra-fine PA6 fibers (2-5 μm) were obtained by an environment-friendly water-splitting process. The "sea" phase (TPVA) in sea-island fiber could be removed quickly by boiling water treatment in 3 min. This green and energy-saving sea-island fiber splitting technique is of great significance in reducing CO₂ emissions during the preparation of super-fine fibers.

Innovative Green Chemistry Approach to Synthesis of Sn2+-Metal Complex and Design of Polymer Composites with Small Optical Band Gaps

In this work, the green method was used to synthesize Sn2+-metal complex by polyphenols (PPHs) of black tea (BT). The formation of Sn2+-PPHs metal complex was confirmed through UV-Vis and FTIR methods. The FTIR method shows that BT contains NH and OH functional groups, conjugated double bonds, and PPHs which are important to create the Sn2+-metal complexes. The synthesized Sn2+-PPHs metal complex was used successfully to decrease the optical energy band gap of PVA polymer. XRD method showed that the amorphous phase increased with increasing the metal complexes. The FTIR and XRD analysis show the complex formation between Sn2+-PPHs metal complex and PVA polymer. The enhancement in the optical properties of PVA was evidenced via UV-visible spectroscopy method. When Sn2+-PPHs metal complex was loaded to PVA, the refractive index and dielectric constant were improved. In addition, the absorption edge was also decreased to lower photon. The optical energy band gap decreases from 6.4 to 1.8 eV for PVAloaded with 30% (v/v) Sn2+-PPHs metal complex. The variations of dielectric constant versus wavelength of photon are examined to measure localized charge density (N/m*) and high frequency dielectric constant. By increasing Sn2+-PPHs metal complex, the N/m* are improved from 3.65 × 1055 to 13.38 × 1055 m-3 Kg-1. The oscillator dispersion energy (Ed) and average oscillator energy (Eo) are measured. The electronic transition natures in composite films are determined based on the Tauc's method, whereas close examinations of the dielectric loss parameter are also held to measure the energy band gap.

An Investigation into the PVA:MC:NH4Cl-Based Proton-Conducting Polymer-Blend Electrolytes for Electrochemical Double Layer Capacitor (EDLC) Device Application: The FTIR, Circuit Design and Electrochemical Studies

In this report, the preparation of solid polymer electrolytes (SPEs) is performed from polyvinyl alcohol, methyl cellulose (PVA-MC), and ammonium chloride (NH4Cl) using solution casting methodology for its use in electrical double layer capacitors (EDLCs). The characterizations of the prepared electrolyte are conducted using a variety of techniques, including Fourier transform infrared spectroscopy (FTIR), electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The interaction between the polymers and NH4Cl salt are assured via FTIR. EIS confirms the possibility of obtaining a reasonably high conductance of the electrolyte of 1.99 × 10-3 S/cm at room temperature. The dielectric response technique is applied to determine the extent of the ion dissociation of the NH4Cl in the PVA-MC-NH4Cl systems. The appearance of a peak in the imaginary part of the modulus study recognizes the contribution of chain dynamics and ion mobility. Transference number measurement (TNM) is specified and is found to be (tion) = 0.933 for the uppermost conducting sample. This verifies that ions are the predominant charge carriers. From the LSV study, 1.4 V are recorded for the relatively high-conducting sample. The CV curve response is far from the rectangular shape. The maximum specific capacitance of 20.6 F/g is recorded at 10 mV/s.

Synthesis and Application of Tackifying Dispersant Poly (Vinyl Alcohol-Acrylic Acid-Triallyl Cyanate)

At present, the thickener market is relatively advanced. Only by imparting thickeners with new properties can they meet the needs of the current market. In this work, a new modified tackifying dispersant poly (vinyl alcohol-acrylic acid-triallyl cyanate) (PVA-AA-t) was prepared via alcoholysis of a random copolymer composed of vinyl acetate (VAc), acrylic acid (AA), and triallyl cyanate (TAC) by a one-step high-temperature solution polymerization in methanol, which was a relatively simple method. The structure of the polymer was characterized by FTIR and TG. FTIR proved the successful synthesis of PVA-AA-t, while TG showed the thermal stability of PVA-AA-t at around 100 °C. The excellent thickening properties of the PVA-AA-t were observed using a nano particle size analyzer and a rotary viscometer. The nano particle size analyzer showed that the PVA-AA-t particles swelled in water to nearly nine times their initial size. The rotary viscometer showed that the viscosity of PVA-AA-t in water increased significantly, while PVA-AA-t was sensitive to electrolytes and pH, which changed the polymer molecular chain from stretched to curled, resulting in a decrease in viscosity. In addition, the dispersion properties of PVA-AA-t and a common thickener as graphene (Gr) dispersants were compared. The results indicate that PVA-AA-t has very good compatibility with Gr, and can effectively disperse Gr, because of the introduction of weak polar molecules (VAc) to the polymer molecules, changing their polarity, meaning that it is possible to use PVA-AA-t in the dispersion of Gr and other industrial applications (such as conductive textile materials, Gr batteries, etc.) derived from it.

Nonionic nontoxic antimicrobial polymers: indole-grafted poly(vinyl alcohol) with pendant alkyl or ether groups

A series of new nonionic antimicrobial polymers with a biodegradable polyvinyl alcohol (PVA) backbone grafted with indole units and different hydrophobic alkyl or ether groups were synthesized by facile esterification.

Synthesis of highly porous three-dimensional PVA/GO/ZIF-67 cryogel for the simultaneous treatment of waters contaminated with cadmium (II) and lead (II) heavy metal ions

In this research, PVA/GO/ZIF-67 cryogel as a highly porous three-dimensional polymeric adsorbent was synthesized by freeze-drying method and applied for the simultaneous removal of Cd2+ and Pb2+ ions from contaminated...

Metal Doped PVA Films for Opto-Electronics-Optical and Electronic Properties, an Overview

Polyvinyl alcohol is unique among polymers. Apart from its preparation, it is not built up in polymerization reactions from monomers, unlike most vinyl-polymers, and it is biodegradable in the presence of suitably acclimated microorganisms. It is an environmentally friendly material for a wide range of applications, from medical ones, based on its biocompatibility, to integrated optics. This paper reviews, in addition to the preparation and optimization of films of polyvinyl alcohol doped with different metal species, the role of dopants and doping technologies in the involved electronic mechanism. The optical properties were studied by UV-VIS-IR, Mössbauer spectroscopy, and other measurement techniques, with applications such as real-time holography, microlasers, optical sensors or nanophotonics in mind.

Characteristics of a Plasticized PVA-Based Polymer Electrolyte Membrane and H+ Conductor for an Electrical Double-Layer Capacitor: Structural, Morphological, and Ion Transport Properties

Poly (vinyl alcohol) (PVA)-based solid polymer electrolytes doped with ammonium thiocyanate (NH4SCN) and glycerol were fabricated using a solution casting method. Lithium-based energy storage devices are not environmentally friendly materials, and they are toxic. Thus, proton-conducting materials were used in this work as they are harmless and are smaller than lithium. The interaction between PVA and the electrolyte elements was shown by FTIR analysis. The highest conductivity of 1.82 × 10-5 S cm-1 was obtained by the highest-conducting plasticized system (PSP_2) at room temperature. The mobility, diffusion coefficient, and number density of anions and cations were found to increase with increasing glycerol. FESEM was used to investigate the influence of glycerol on film morphology. TNM showed that the cations and anions were the main charge carriers. LSV showed that the electrochemical stability window of the PSP_2 system was 1.99 V. The PSP_2 system was applied in the preparation of an electrical double layer capacitor device. The shape of the cyclic voltammetry (CV) curve was nearly rectangular with no Faradaic peaks. From the galvanostatic charge-discharge analysis, the power density, energy density, and specific capacitance values were nearly constant beyond the first cycle at 318.73 W/Kg, 2.06 Wh/Kg, and 18.30 F g-1, respectively, for 450 cycles.

Characteristics of Poly(vinyl Alcohol) (PVA) Based Composites Integrated with Green Synthesized Al3+-Metal Complex: Structural, Optical, and Localized Density of State Analysis

The influence of dispersing Al-metal complex on the optical properties of PVA was investigated using UV–visible spectroscopy. Polymer composite films with various Al³⁺-complex amounts in the PVA matrix were arranged by solution casting technique by means of distilled water as a widespread solvent. The formation of Al³⁺-metal complex was verified through Ultraviolet–visible (UV-Vis) and Fourier-transform infrared spectroscopy (FTIR) examinations. The addition of Al-complex into the polymer matrix led to the recovery of the optical parameters such as dielectric constant (ε_r and ε_i) and refractive index (n). The variations of real and imaginary parts of complex dielectric constant as a function of photon wavelength were studied to calculate localized charge density values (N/m*), high-frequency dielectric constant, relaxation time, optical mobility, optical resistivity, and plasma angular frequency (ω_p) of electrons. In proportion with Al³⁺-complex content, the N/m* values were amplified from 3.68 × 10⁵⁵ kg⁻¹ m⁻³ to 109 × 10⁵⁵ kg⁻¹ m⁻³. The study of optical parameters may find applications within optical instrument manufacturing. The optical band gap was determined from Tauc’s equation, and the type of electronic transition was specified. A remarkable drop in the optical band gap was observed. The dispersion of static refractive index (n_o) of the prepared composites was analyzed using the theoretical Wemple–DiDomenico single oscillator model. The average oscillator energy (E_o) and oscillator dispersion energy (E_d) parameters were estimated.

The Study of Structural, Impedance and Energy Storage Behavior of Plasticized PVA:MC Based Proton Conducting Polymer Blend Electrolytes

In this study, structural characterization, electrical properties and energy storage performance of plasticized polymer electrolytes based on polyvinyl alcohol/methylcellulose/ammonium thiocyanate (PVA/MC-NH₄SCN) were carried out. An X-ray diffraction (XRD) study displayed that the plasticized electrolyte system with the uppermost value of direct current (DC) ionic conductivity was the most amorphous system. The electrolyte in the present work realized an ionic conductivity of 2.903 × 10⁻³ Scm⁻¹ at room temperature. The main charge carrier in the electrolyte was found to be the ions with the ionic transference number (t_ion) of 0.912, compared to only 0.088 for the electronic transference number (t_elec). The electrochemical stability potential window of the electrolyte is 2.1 V. The specific capacitance was found to reduce from 102.88 F/g to 28.58 F/g as the scan rate increased in cyclic voltammetry (CV) analysis. The fabricated electrochemical double layer capacitor (EDLC) was stable up to 200 cycles with high efficiency. The specific capacitance obtained for the EDLC by using charge–discharge analysis was 132.7 F/g at the first cycle, which is slightly higher compared to the CV plot. The equivalent series resistance (ESR) increased from 58 to 171 Ω throughout the cycles, which indicates a good electrolyte/electrode contact. Ions in the electrolyte were considered to have almost the same amount of energy during the conduction process as the energy density is approximately at 14.0 Wh/kg throughout the 200 cycles. The power density is stabilized at the range of 1444.3 to 467.6 W/kg as the EDLC completed the cycles.

Tea from the drinking to the synthesis of metal complexes and fabrication of PVA based polymer composites with controlled optical band gap

In the present study black tea extract (BTE) solution which is familiar for drinking was used to prepare cerium metal-complexes (Ce(III)-complex). The prepared Ce(III)-complex was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV–Vis spectroscopy. The results indicate that BTE solution is a novel green coordination chemistry approach for the synthesis of metal complexes. The outcomes signify that coordination occurs between cerium cations and polyphenols. The synthesis of metal-complexes with superior absorption performance in the visible region is a challenge for optoelectronic device applications. The suspended Ce(III)-complex in distilled water was mixed with poly (vinyl alcohol) (PVA) polymer to fabricate PVA/ Ce(III)-complex composites with controlled optical properties. The PVA/Ce(III)-complexes composite films were characterized by FTIR, XRD, and UV–Vis spectroscopy. The XRD findings confirms the amorphous structure for the synthesized Ce(III)-complexes. The addition of Ce(III)-complex into the PVA host polymer led to the growth of polymer composites with controllable small optical band gaps. It is shown by the FTIR spectra of the composite films that the functional groups of the host PVA have a vigorous interaction with the Ce(III)-complex. The XRD deconvolution on PVA composites reveals the amorphous phase enlargement with increasing Ce(III)-complex concentration. It is indicated in the atomic force microscopy (AFM) that the surface roughness in the doped PVA films increases with the increase of the Ce(III)-complex. There is a decrease in absorption edge from 5.7 to 1.7 eV. It becomes possible to recognize the type of electron transition by studying both the Tauc's model and optical dielectric loss (ɛ_i) parameter.

Aziz S, Anuar H, Dannoun EMA, Ali F, Abdulwahid RT, Al-Zangana S, Kadir MF. The Study of EDLC Device with High Electrochemical Performance Fabricated from Proton Ion Conducting PVA-Based Polymer Composite Electrolytes Plasticized with Glycerol

In the present work, a novel polymer composite electrolytes (PCEs) based on poly(vinyl alcohol) (PVA): ammonium thiocyanate (NH₄SCN): Cd(II)-complex plasticized with glycerol (Gly) are prepared by solution cast technique. The film structure was examined by XRD and FTIR routes. The utmost ambient temperature DC ionic conductivity (σ_DC) of 2.01 × 10⁻³ S cm⁻¹ is achieved. The film morphology was studied by field emission scanning electron microscopy (FESEM). The trend of σ_DC is further confirmed with investigation of dielectric properties. Transference numbers of ions (t_ion) and electrons (t_el) are specified to be 0.96 and 0.04, respectively. Linear sweep voltammetry (LSV) displayed that the PCE potential window is 2.1 V. The desired mixture of activated carbon (AC) and carbon black was used to fabricate the electrodes of the EDLC. Cyclic voltammetry (CV) was carried out by sandwiching the PCEs between two carbon-based electrodes, and it revealed an almost rectangular shape. The EDLC exhibited specific capacitance, energy density, and equivalent series resistance with average of 160.07F/g, 18.01Wh/kg, and 51.05Ω, respectively, within 450 cycles. The EDLC demonstrated the initial power density as 4.065 × 10³ W/Kg.

A Comprehensive Review on Optical Properties of Polymer Electrolytes and Composites

Polymer electrolytes and composites have prevailed in the high performance and mobile marketplace during recent years. Polymer-based solid electrolytes possess the benefits of low flammability, excellent flexibility, good thermal stability, as well as higher safety. Several researchers have paid attention to the optical properties of polymer electrolytes and their composites. In the present review paper, first, the characteristics, fundamentals, advantages and principles of various types of polymer electrolytes were discussed. Afterward, the characteristics and performance of various polymer hosts on the basis of specific essential and newly published works were described. New developments in various approaches to investigate the optical properties of polymer electrolytes were emphasized. The last part of the review devoted to the optical band gap study using two methods: Tauc's model and optical dielectric loss parameter. Based on recently published literature sufficient quantum mechanical backgrounds were provided to support the applicability of the optical dielectric loss parameter for the band gap study. In this review paper, it was demonstrated that both Tauc's model and optical dielectric loss should be studied to specify the type of electron transition and estimate the optical band gap accurately. Other parameters such as absorption coefficient, refractive index and optical dielectric constant were also explored.

Formulation and optimization of drug-loaded mesoporous silica nanoparticle-based tablets to improve the dissolution rate of the poorly water-soluble drug silymarin

Porous carriers have been put forward as a promising alternative for stabilizing the amorphous state of loaded drugs, and thus significantly improving the dissolution rate of poorly soluble compounds. The purpose of this study was to enhance the saturation solubility, dissolution rate and drug loading of the poorly water-soluble drug silymarin via incorporation into mesoporous silica nanospheres within a lyophilized tablet to obtain a unique formulation. 3² full factorial design was applied to study the effect of both independent variables, polyvinyl alcohol (PVA) as stabilizer and binder and sucrose as cryoprotectant and disintegrant; and on the dependent variables that included the mean particle size (Y₁), disintegration time (Y₂), tablet strength (Y₃) and % of drug release after 2 min, R_2min,Y₄. The drug-loaded mesoporous silica nanospheres and the optimized formula was evaluated by different characterization methods: scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry, X-ray diffractometry and Fourier transform infrared spectroscopy; as well as drug content, saturation solubility and moisture content. The evaluation demonstrated that the loaded mesoporous silica nanospheres and the optimized formula are in amorphous state without any chemical interaction with the silica matrix or the stabilizer. Moreover, the drug was stably maintained in nanosize range with narrow particle size distribution. Furthermore, the optimized lyophilized tablets had highly porous structure, low friability (less than 1%), fast disintegration (less than 30 s), high tablet strength, low moisture content (less than 1%), remarkably increased dissolution rate and noticeable improvement in saturation solubility.

From Green Remediation to Polymer Hybrid Fabrication with Improved Optical Band Gaps

The present work proposed a novel approach for transferring high-risk heavy metals tometal complexes via green chemistry remediation. The method of remediation of heavy metals developed in the present work is a great challenge for global environmental sciences and engineering because it is a totally environmentally friendly procedure in which black tea extract solution is used. The FTIR study indicates that black tea contains enough functional groups (OH and NH), polyphenols and conjugated double bonds. The synthesis of copper complex was confirmed by the UV-vis, XRD and FTIR spectroscopic studies. The XRD and FTIR analysis reveals the formation of complexation between Cu metal complexes and Poly (Vinyl Alcohol) (PVA) host matrix. The study of optical parameters indicates that PVA-based hybrids exhibit a small optical band gap, which is close to inorganic-based materials. It was noted that the absorption edge shifted to lower photon energy. When Cu metal complexes were added to PVA polymer, the refractive index was significantly tuned. The band gap shifts from 6.2 eV to 1.4 eV for PVA incorporated with 45 mL of Cu metal complexes. The nature of the electronic transition in hybrid materials was examined based on the Taucs model, while a close inspection of the optical dielectric loss was also performed in order to estimate the optical band gap. The obtained band gaps of the present work reveal that polymer hybrids with sufficient film-forming capability could be useful to overcome the drawbacks associated with conjugated polymers. Based on the XRD results and band gap values, the structure-property relationships were discussed in detail.

Structural and Optical Characteristics of PVA:C-Dot Composites: Tuning the Absorption of Ultra Violet (UV) Region

: In this work the influence of carbon nano-dots (CNDs) on absorption of ultra violet (UV) spectra in hybrid PVA based composites was studied. The FTIR results reveal the complex formation between PVA and CNDs. The shifting was observed in XRD spectrum of PVA:CNDs composites compared to pure PVA. The Debye-Scherrer formula was used to calculate the crystallite size of CNDs and crystalline phases of pure PVA and PVA:CNDs composites. The FESEM images emphasized the presence and dispersion of C-dots on the surface of the composite samples. From the images, a strong and clear absorption was noticed in the spectra. The strong absorption that appeared peaks at 280 nm and 430 nm can be ascribed to the n-π* and π-π* transitions, respectively. The absorption edge shifted to lower photon energy sides with increasing CNDs. The luminescence behavior of PVA:CNDs composite was confirmed using digital and photo luminescence (PL) measurements. The optical dielectric constant which is related to the density of states was studied and the optical band gap was characterized accurately using optical dielectric loss parameter. The Taucs model was used to determine the type of electronic transition in the samples.

Facile synthesis of branched polyvinyl acetate via redox-initiated radical polymerization

Although branched polymers find widespread applications, the rational design and synthesis of branched vinyl polymers via the conventional radical (co)polymerization of commercially available monomers is still a challenge for researchers in this field.

Polyvinyl alcohol-based hydrophilic monoliths from water-in-oil high internal phase emulsion template

Herein, we report a new approach to fabricate polyvinyl alcohol (PVA) based hydrophilic monoliths by alcoholysis of porous emulsion-templated polyvinyl acetate (PVAc). The precursory PVAc-based monolith is obtained by polymerization of a W/O high internal phase emulsion (HIPE) containing vinyl acetate as the external phase while water as the internal phase. As an alcoholysis-stable tri-functional commonomer, triallyl isocyanurate is chosen as the crosslinking agent to prevent possible collapse of the polymeric skeleton and the consequent losses in mechanical properties during the alcoholysis step. By alcoholysis of the resulting PVAc-based monolith, the PVA-based monoliths are successful prepared as confirmed by FTIR analysis. BET analysis and SEM observation confirm the formation of open-cell and highly interconnected porous structures of PVA-based monoliths with surface areas of around 16m²/g. Stemming from the intrinsic hydrophilicity of hydroxyl and morphology, PVA-based monoliths exhibit great enhancement in hydrophilicity with a much lower water contact angles than that of PVAc-based monoliths.

Poly(vinyl alcohol)/graphene oxide nanocomposites prepared by in situ polymerization with enhanced mechanical properties and water vapor barrier properties

A novel and one-stepin situpolymerization method for preparing the poly(vinyl alcohol) (PVA)/graphene oxide (GO) nanocomposites.