Poly Vinyl Alcohol Composite Films Research Articles

Fabrication of PVA-based electromagnetic interference shielding composite film by improving the dispersibility of carbon nanomaterial via m-LDH modification

A good dispersion of carbon (C) nanoparticles is a crucial factor to ensure good electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) performance of polymer-based composite films. In the present work, water-dispersed monolayer layered double hydroxides (m-LDH) was used to modify the C nanoparticles via an in-situ growth method and applied as the conductive fillers for polyvinyl alcohol (PVA) composite films. The prepared C@m-LDH hybrids displayed good water dispersibility due to the in-situ growth of m-LDH with high dispersibility and small particle size on the surface of C nanoparticles, as well as the synergistic effect of styrene-maleic anhydride copolymer attached to the m-LDH surface. The property testing experiments for the PVA composite films demonstrated that compared with pristine C nanoparticles, as-prepared C@m-LDH hybrids exhibited greatly enhanced the electrical conductivity and higher EMI SE performance. Moreover, PVA/C@m-LDH composite film exhibit remarkably low permeation thresholds, especially PVA/CB@m-LDH composite film, CB@m-LDH content is only 0.4 wt%. In order to further improve the electrical conductivity and EMI SE performance, hybrid fillers of CB@m-LDH/CNT@m-LDH were added in the composite films with different mass ratios. Among, the polymer composite films containing 30 wt% CB@m-LDH/CNT@m-LDH with a mass ratio of 12:1 achieves a high EMI SE value up to 29 dB at a thickness of 0.2 mm, indicating the potential use of these materials for electromagnetic shielding application in the X-band frequency region. The present study paves the way for designing high-performance polymer-based composite film by Cnanoparticles functionalization and altering processing conditions for efficient microwave shielding material.

Physicochemical Properties of Cellulose Nanocrystals Extracted from Postconsumer Polyester/Cotton-Blended Fabrics and Their Effects on PVA Composite Films

The utilisation of cotton waste as precursors in the synthesis of nanocrystalline cellulose has gained significant attention. This approach suggests a sustainable solution to address the growing concern of textile waste accumulation while simultaneously producing a valuable material. The main aim of this study is to examine the properties of cellulose nanocrystals (CNCs) obtained from postconsumer polyester–cotton waste and assess the effect of different fabric structures on the extraction and these properties. To acquire nanocellulose, a thorough decolourisation pretreatment process was utilised, which involved the treatment of polyester–cotton waste with sodium dithionite and hydrogen peroxide. Consequently, the postconsumer material was then treated with an acid hydrolysis method employing a 64% (v/v) sulphuric acid solution at 50 °C for 75 min, resulting in the formation of CNCs with average yield percentages ranging from 38.1% to 69.9%. Separation of the acid from the CNC was facilitated by a centrifugation process followed by dialysis against deionised water. Uniform dispersion was then achieved using ultrasonication. A variety of analytical techniques were employed to investigate the morphological, chemical, thermal, and physical properties of the isolated CNCs. Among these techniques, attenuated total reflection-Fourier-transform infrared spectroscopy (ATR-FTIR), energy-filtered transmission electron microscopy (EF-TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) were utilised to analyse the CNCs. The findings indicated that the separated CNCs exhibited a rod-shaped morphology, measuring between 78 and 358 nm in length and 5 and 16 nm in diameter, and also exhibited high crystallinity (75–89%) and good thermal stability. The extracted CNCs were mixed with polyvinyl alcohol (PVA) and glycerol to assess their reinforcing effect on plastic films. The prepared composite film exhibited improved mechanical properties and thermal stability. Incorporating CNCs led to a 31.9% increase in the tensile strength and a 42.33% rise in the modulus of elasticity. The results from this research proved that CNCs can be extracted from postconsumer mixed fabrics as a potential solution to effectively address the mounting concerns surrounding waste management in the textile industry and also provide avenues for enhancing the qualities of eco-friendly composite films.

STUDYING THE PHYSICAL PROPERTIES OF PVA-PEG LOADED WITH DIFFERENT CONCENTRATIONS OF LIGNOSULFONATE

Polyvinyl Alcohol (PVA) and Polyethylene Glycol (PEG) blend composite films were prepared using the casting technique. The study aims to investigate the effect of the addition of various Lignosulfonate (LS) concentrations at (0.01, 0.02, and 0.04 wt %) on the optical and structural properties of the PVA/PEG using UV–VIS spectroscopy and X-ray diffraction (XRD). The results showed that the addition of LS led to a more compact structure of PVA/PEG, which increased its refractive index and amorphous phase. This resulted in a reduction in the optical energy gap that could be attributed to the increase in the disordered structure of the composites. Additionally, the Absorbance of PVA/PEG/LS composite film increased as the LS doping concentration increasedin the matrix. These results reflect the proper dispersion of LS into the PVA/PEGmatrix, causing a strong intermolecular interaction between LS and PVA/PEG blends, suggesting strong hydrogen bond formation between the hydroxyl group in PVA chains and the outer site groups of LS.This study has yielded significant insights that may aid in the advancement of polymer applications in industries by reducing costs. Theseresults could be instrumental in enhancing production processes and making the use of polymers a more viable and cost-effective option for industrial operations.

Investigating the annealing effects on the performance of polyvinyl alcohol-graphite-based triboelectric nanogenerator

Annealing plays a crucial role in enhancing the performance, stability, and durability of triboelectric nanogenerators (TENGs). By carefully controlling the annealing parameters, the material properties can be optimized and improve the overall efficiency of TENG devices for various practical applications. Herein, graphite (Gr) embedded polyvinyl alcohol (PVA) composite films are prepared by a solution casting technique and subjected to annealing at various temperatures below the glass transition temperature (Tg) of PVA. The annealed effects are thoroughly examined through characterizations involving PXRD, SEM, EDS, FTIR, and TGA. Subsequently, TENGs are fabricated utilizing the annealed composite films as the tribopositive material, polypropylene as the tribonegative material, and the impact of annealing on the device performance is investigated. At an annealing temperature of 80°C, the PVA-Gr TENG exhibited notably higher output voltage (VOC) and short-circuit current (ISC) of 200.24 V and 12.68 µA, respectively. In addition, the PVA-Gr TENG successfully charges electrolytic capacitors, powers a digital watch, operates a humidity and temperature sensor, and lights a series of green LEDs. Thus, the present study highlights the significant impact of annealing on the performance of PVA-Gr TENG, leading to enhanced output power and stability.

Cellulose Extraction From Green Algae, Ulva Ohnoi, and Its Application to PVA‐Based Antibacterial Composite Films Incorporated With Zinc Oxide Nanoparticles

ABSTRACTCellulose was successfully extracted from green algae (Ulva ohnoi) by chemical treatments. The contents of holocellulose and α‐cellulose significantly increased from 37.6% and 3.3% to 82.5% and 63.3%, respectively, after whole extraction treatments. The extracted cellulose (EC) was mixed to polyvinyl alcohol (PVA) to prepare EC/PVA composite films with polyethylene glycol (PEG) or glycerol (GLY) as a plasticizer. The EC/3%PVA composite film showed the highest tensile strength of 54.42 MPa because of the high PVA content. Adding GLY steeply increased the elongation of the EC/3%PVA film from 3.12% to 126.76%, but adding PEG slightly decreased to 2.63%. The EC/1%PVA/PEG composite film showed the highest visible light transmittance of 84.47%, while the addition of zinc oxide nanoparticles (ZnO‐NPs) significantly improved UV‐blocking properties. In addition, the incorporation of ZnO‐NPs on the EC/PVA‐based composite films showed excellent antibacterial activity against six Gram‐positive and Gram‐negative bacteria.

An antimicrobial film of silver/nanocellulose crystal/oxalic acid/polyvinyl alcohol with real-time bactericidal and prevention of biofilm formation properties

Silver nanoparticles (AgNPs) is an excellent antibacterial agent, which is widely used in medical, food, environmental and other fields, but AgNPs are easy to accumulate in aqueous solution, so their application in various fields is limited. Therefore, it is particularly important to propose a new application method or to prepare a new composite material. In this study, OA/PVA was obtained by cross-linking oxalic acid (OA) with polyvinyl alcohol (PVA). Then Ag/NCC was obtained by in situ reduction of AgNPs on nanocellulose crystals (NCC). Finally, Ag/NCC/OA/PVA composite antimicrobial films with good waterproofing effect were prepared by mixing Ag/NCC with OA/PVA. Subsequently, the films were characterized using SEM, UV–vis, FTIR and XRD, as well as physicochemical properties such as mechanical strength and hydrophilic properties were determined. The results indicated that the Ag/NCC/OA/PVA films possess good light transmittance, mechanical properties, water resistance, antibacterial activity, and biodegradability. The results of the mechanism study showed that Ag/NCC/OA/PVA films can destroy cell integrity, inhibit succinate dehydrogenase (SDH) activity, thereby reducing intracellular ATP levels. And induce a large number of reactive oxygen species (ROS) production, eventually leading to the death of C. sakazakii. In summary, Ag/NCC/OA/PVA film has good physical and chemical properties, antibacterial activity and biocompatibility, and has promising applications in food and medical antibacterial fields.

Preparation and Properties of Polyvinyl Alcohol (PVA) Composite Films by Incorporation of Octadecylamine Polyoxyethylene Ether Modified Carbon Black Particles as Filler

In our research described here, a strong acid oxidizing agent was selected to modify the surface of carbon black (CB) to obtain oxidized carbon black (OCB) particles. These OCB particles were then subjected to an ionic bonding reaction with alkaline amine groups present on the surface of octadecylamine polyoxyethylene ether (AC1830) in the form of a paste, resulting in the production of polyether amine-modified oxidized carbon black particles (A-CB). FTIR confirmed the successful production of the A-CB particles. The PVA composite films were prepared using the casting method with varying amounts of A-CB as filler and PVA as the matrix. The films were then analyzed using tensile, scanning electron microscopy, dynamic thermo-mechanical analysis, DSC, and water absorption testing. The results showed that the tensile strength was highest at 3% A-CB, reaching 154.85 MPa. A-CB was well dispersed in PVA at low contents (1% and 3%). The loss modulus, energy storage modulus, crystallinity, and crystallization rate of the A-CB/PVA films improved compared to PVA films. Additionally, the issue of excessive water absorption in A-CB/PVA has been improved.

Antimicrobial evaluation of composite films based on polyvinyl alcohol/triazolopyrimidenes/selenium nanoparticles

Background Using ultrasonic waves, a multi-component reaction of aminotriazole, carbonyl compounds and cyanoester derivatives, triazolopyrimidines are created with outstanding yields in a shorter amount of time. Selenium nanoparticles (SeNPs) with outstanding biological activity combined with triazolopyrimidine can imply promising materials for different biological applications. Objective Synthesis of triazolopyrimidine compounds conjugated with SeNPs and their incorporation into biodegradable polyvinyl alcohol for antimicrobial application were investigated. Methods The synthesized triazole derivatives were used in the synthesis of in situ SeNPs. The synthesized triazole derivatives and SeNPs were blended with polyvinyl alcohol (PVa) to prepare composite films. All synthesized compounds were confirmed using FT-IR, 1H-NMR, mass spectroscopy and elemental analysis. The prepared PVa composite films with nanoparticles were tested against Gram-positive (+ ve) and Gram-negative (−ve) bacteria. Results The treated PVA with the SeNPs showed high biological efficiency compared with PVA treated with triazole derivatives.

Preparation and properties of Polyvinyl alcohol (PVA) composite films by incorporation of γ- aminopropyltriethoxysilane(APTES) modified mesoporous silica (SBA-15) as filler

In this work, a mesoporous silica (SBA-15) was synthesized using a hydrothermal method and the surface of the SBA-15 was further modified by utilizing the organosilane compound γ- aminopropyltriethoxysilane(APTES); FT-IR testing confirmed the successful grafting of these organic groups onto the surface of the SBA-15, the result being the AP-S. Composite films were subsequently prepared through a casting method, with SBA-15 and AP-S serving as the inorganic filler particles, and PVA acting as the matrix material. These films were characterized by tensile texts, dynamic mechanical analysis, scanning electron microscopy, and dielectric measurements. The results showed that the tensile modulus, loss modulus and dielectric properties of the modified AP-S/PVA composite films were improved compared with those of SBA-15/PVA, with the tensile strength being the largest at 145.25 MPa when the AP-S content was 2%. This result combined with the SEM analysis, shows that the incorporation of SBA-15 modified by APTES into PVA films can effectively improve the dispersion of SBA-15 in the PVA films, which can also explain the performance enhancement.

Strong, UV-blocking, and hydrophobic PVA composite films containing tunable lignin nanoparticles

In the present work, hollow and solid lignin nanoparticles (LNPs) were synthesized through a self-assembling process using the organosolv pretreatment of lignin from the eucalyptus and willow byproducts. The SEM, TEM, and zeta potential establish the LNPs of a uniform spherical morphology, and the hollow lignin nanoparticles (HLNPs) display the inner cavity and shell. The polyvinyl alcohol (PVA) nanocomposite films containing the LNPs suggest that the presence of HLNPs results in a “room” like network structure in the films and differs from the solid lignin nanoparticles (SLNPs) induced structural changes. The LNPs inclusion increases the mechanical properties. The films with solid eucalyptus lignin nanoparticles showed excellent tensile strength (132 MPa), while those with hollow eucalyptus lignin nanoparticles resulted in exceptional elongation at break (324%). Hydrophobicity tests revealed that both LNPs incorporation in the PVA film results in a water contact angle of more than 90°. The outcome promises novel opportunities for LNPs in the designing and development of plastic replacement packaging films.

Passively mode-locked erbium-doped fiber laser by a Mo2TiC2 MXene saturable absorber

Mono- and few-layer MXenes have gained widespread use as a nonlinear material platform for saturable absorbers (SAs) when generating ultrafast mode-locked pulses. However, the manufacturing processes associated with these materials are intricate and require considerable expertise. Consequently, it would be intriguing to investigate whether bulk and/or nanoscale-layered MXenes can be used as a nonlinear optical material platform. In this study, we experimentally demonstrated a Mo2TiC2 MXene-based SA by depositing nanoscale-layered Mo2TiC2 MXene particles and a polyvinyl alcohol composite film onto a side-polished fiber device. The fabricated SA exhibited a modulation depth of 5.67% and a saturation intensity of 0.135 MW/cm2. By integrating the Mo2TiC2 MXene-based SA within an erbium-doped fiber ring cavity, we generated mode-locked pulses featuring a pulse width of 1.74 ps at a wavelength of 1557.9 nm. This investigation highlights the potential of nanoscale-layered Mo2TiC2 MXene to function as an efficient material platform for nonlinear photonics applications.

Improvement of biodegradable polymer film properties by incorporating functionalized few-layer graphene

Functionalized few-layer graphene (FFG) prepared employing an eco-friendly liquid exfoliation method using coffee waste extract was added to three biological and one synthetic polymers. Chitosan/FFG, polyvinyl alcohol (PVA)/FFG, sodium alginate/FFG, and gelatin/FFG composite films were developed using variable concentrations of FFG (0–1 wt% of polymer). The developed films were characterized for water content, swelling degree, thickness, thermal and mechanical properties, water vapor permeability, and indoor soil burial degradation. In comparison to the pure chitosan, PVA, sodium alginate, and gelatin films, the inclusion of FFG significantly increased the tensile strength up to 439%, 247%, 190%, and 195%, respectively. Moreover, the Young’s modulus of the developed composite films was improved up to 515%, 253%, 144%, and 341%, respectively. The elongation at break of chitosan and PVA films declined with FFG concentration, while the maximum elongation at break existed for sodium alginate/FFG and gelatin/FFG films. The water vapor permeability of chitosan, PVA, sodium alginate, and gelatin composite films decreased by 87%, 67%, 50%, and 55%, respectively, with the addition of only 1% FFG. The incorporation of FFG reduced both the water content and swelling degree of all composite films. In addition, the composite films showed similar degradation after addition of FFG in the 60-day soil burial test.

Graphene Nanoplatelet and Multiwalled Carbon Nanotube Doping Effect on the Structural and Physical Properties of PolyVinyl Alcohol Composites

Polyvinyl alcohol (PVA) composite thin films were prepared using graphene nanoplatelets (GNPs) and multiwalled carbon nanotubes (MWCNTs) as carbon fillers (CFs). The resulting electrical, optical, mechanical, and structural changes caused by adding the CFs to the pure PVA matrix were characterized. The improvement of electrical, optical, and mechanical properties was interpreted in terms of the percolation theory. Depending on this interpretation, the percolation threshold values, and the critical exponential values of the related properties were calculated. It turns out that the measured mechanical and optical changes were compatible with the site percolation theory while the electrical conductivity was compatible with the classical percolation theory. X-ray diffraction (XRD) measurements were performed to correlate the physical properties with the structure of the PVA composite films. They revealed that the degree of crystallinity of the composites increased with the CF reinforcement and that MWCNT was more effective in improvement of the crystallinity of the PVA composites than GNP.

SPR studies in PVA composite films of SiO2@NaYF4:Er3+/Yb3+ UCNPs via AuNPs concentration variation and their temperature sensing applications

The composite film of mesoporous silica coated NaYF4:Er3+/Yb3+ upconversion nanoparticles and gold nanoparticles (AuNPs) in Poly vinyl alcohol (PVA) medium were prepared. The effect of the concentrations of AuNPs with 0 µl, 50 µl, 100 µl and 150 µl on the structure and upconversion luminescence intensity were studied. The phenomenon of enhancement in upconversion luminescence intensity due to AuNPs were explained via surface plasmon resonance (SPR) phenomenon. Apart from this the XRD, FE-SEM and AFM studies were done for estimation of structure and surface morphology etc. The impurities were estimated through FTIR analysis. The optical properties of these polymer composite films were studied via UV–vis absorption spectra and upconversion luminescence spectra analysis. A low temperature sensing ability of these films have been demonstrated for the suitability of these films in bio-medical applications.

Simultaneously Monitoring Humidity and Temperature Based on Waveguide Bragg Grating Sensor Chip

Herein, we proposed and demonstrated a novel relative humidity (RH) sensing chip with temperature compensation, which is based on waveguide Bragg grating (WBG) assisted with polyvinyl alcohol (PVA) and polydimethylsiloxane (PDMS) composite film. Half of the cladding of the WBG region was corroded with hydrofluoric acid, which results in a split of the Bragg peak into two peaks. The PVA-PDMS composite film coated on the surface of the corroded region shows a high sensitivity to RH due to the hydrophilic hydroxyl groups of PVA film. PDMS not only enhances the stability of the composite film, but also reduces the RI of the PVA film, which restricts the energy loss of the light passing through. In our experiment, average RH sensitivities of -12.2 pm/RH% and 0 pm/RH% in the RH range of 50%-90%, and temperature sensitivities of 9.6 pm/°C and 9.8 pm/°C were obtained by the two peaks shift, respectively. We testified that the simultaneous measurement of RH and temperature can be achieved by the sensitivity matrix method. Furthermore, the proposed sensor possesses remarkable stability and excellent repeatability. Such a cost-effective, integrated, easily fabricated, and reflection power detection-based humidity sensor promises great application prospects in the fields of agriculture, food industry, biological field and other production activities.

Thermal transfer improvement in polyvinyl alcohol films by mixing with boron nitride nanotubes synthesized using a radio-frequency inductively coupled thermal plasma

Boron nitride nanotubes (BNNTs)/polyvinyl alcohol (PVA) composite films were fabricated to enhance heat transfer capabilities. The incorporation of just 1 wt% of BNNTs into PVA resulted in a remarkable six-fold improvement in heat transfer properties. The BNNTs used in the composite films were synthesized using a thermal plasma method, exhibiting high aspect ratio with diameters ranging from 3 nm to 6 nm. The BNNTs improved the formation of heat transfer networks throughout the PVA films, resulting in enhanced heat transfer properties as compared to both pure PVA and BN nano-powder/PVA composite films. In addition, the addition of BNNTs did not adversely affect the mechanical properties of the BNNTs/PVA composite film such as durability and mechanical strength.

Fabrication of CNTs-reinforced poly(vinyl alcohol) nanocomposite film with tailored structural, surface chemical and optical properties

Purpose This study aims to fabricate multiwalled carbon nanotubes (MWCNTs)-mediated polyvinyl alcohol (PVA) composite films using the solution casting approach. Design/methodology/approach The prepared films were evaluated for diverse structural, surface, optical and electrical attributes using advanced analytical techniques, i.e. electron microscopy for surface morphology, Fourier transform infrared spectroscopy for tracing chemical functionalities, x-ray diffraction (XRD) for crystal patterns, water contact angle (WCA) analysis for surface wettability and UV visible spectroscopy for optical absorption parameters. The specimens were also investigated for certain rheological, mechanical and electrical properties, where applicable. Findings The surface morphology results expressed a better dispersion of MWCNTs in the resultant PVA-based nanocomposite film. The XRD analysis exhibited that the nanocomposite film was crystalline. The surface wettability analysis indicated that with the inclusion of MWCNTs, the WCA of the resultant nanocomposite film improved to 89.4° from 44° with the pristine PVA film. The MWCNTs (1.00%, w/w) incorporated PVA-based film exhibited a tensile strength of 54.0 MPa as compared to that of native PVA as 25.3 MPa film. There observed a decreased bandgap (from 5.25 to 5.14 eV) on incorporating the MWCNTs in the PVA-based nanocomposite film. Practical implications The MWCNTs’ inclusion in the PVA matrix could enhance the AC conductivity of the resultant nanocomposite film. The prepared nanocomposite film might be useful in designing certain optoelectronic devices. Originality/value The results demonstrated the successful MWCNTs mediation in the PVA-based composite films expressed good intercalation of the precursors; this resulted in decreased bandgap, usually, desirable for optoelectronic applications.

Enhanced microwave absorption properties of magnetite nanoparticles decorated multi walled carbon nanotubes loaded polyaniline/polyvinyl alcohol nanocomposites

AbstractElectromagnetic radiation interference (EMI) or pollution is increased significantly in proportion to the expansion of electronic and communication industries, which lead to the disturbance of the functioning of electronic gadgets and medical equipments, in addition to the human health damage. The Microwave absorbing (MA) composite comprised of polyvinyl alcohol (PVA), polyaniline (PANI), carbon nanotube (MWCNT) and iron oxide (Fe3O4) has been developed with various proportions, denoted as PVA/PANI/MWCNT/Fe3O4 (1%, 3%, 5%). Fe3O4 was prepared using a hydrothermal method, and PVA/PANI/MWCNT/Fe3O4 (1%, 3%, 5%) nanocomposites was made by solvent casting techniques. The PVA composite films were also subjected to a range of analyses including IR, TGA, DTA, DTG, SEM, TEM, dielectric measurements and EMI shielding effectiveness (EMI SE), to describe their characteristics. The results of various studies indicate that the PVA/PANI/MWCNT/Fe3O4 (1%, 3%, 5%) composites possess enhanced thermal and dielectric characteristics, for instance the PVA/PANI/MWCNT/5% Fe3O4 blend nanocomposites possess 10% initial decomposition at 220°C and dielectric constant of 3.2 × 107 at 1 MHz. The total EMI SE value for the synthetic PVA/PANI/MWCNT/Fe3O4 was found at 9.2 and 10 GHz is 48 and 54 dB, respectively, exhibiting synergistic properties of the composites toward EMI shielding. The microwave absorption spectra indicate two absorption peaks in the region around 8 to 12 GHz, with the absorption reflection loss (RL) value of −20 dB at 10 GHz for the PVA/PANI/MWCNT/5% Fe3O4 nanocomposites.

Bilayer PVA composite film with structural color for high-performance and multifunctional sensing

Intelligent E-skins attract lots of attention for their potential in health monitoring, human-computer interaction, and soft-body robotics. In this work, a colorful multifunctional E-skin sensor with a Janus structure was constructed by solution casting of polyvinyl alcohol (PVA) with clay and carbon nanoparticles on a patterned PDMS template. The halloysite nanotubes (HNTs) and carbon nanoparticles (C) derived from Chinese ink were introduced into PVA to obtain a nano-reinforced layer (top) with structural color and multi-functional layer (bottom) for detection of pressure, temperature, and humidity. Uniformly dispersed HNTs greatly improves the mechanical properties of PVA (up to 46.8 MPa at 303.9% strain). The difference in water absorption of the two layers provides excellent sensitivity to humidity, so it can be used as contactless password unlocking, closing and blooming of bionic flowers, and humidity alarm. The device can achieve object capture and release within 12 s by turning on and off the xenon light. Furthermore, the sensor responds distinctly to pressure and can track human activities such as drinking motion and finger bending, which can also detect the temperature by resistance change. This work provides a materials design strategy for E-skin aimed to applications in robotics, artificial intelligence, prosthetics, and health monitoring.

High intrinsic thermal conductive polymer films by engineered interchain hydrogen bond interactions

AbstractA series of polyvinyl alcohol (PVA) composite films containing different hydrogen bond acceptors 4,4′‐dihydroxydiphenyl (BP), 1,1′‐biphenyl‐4,4′‐diyl dihexanoate (DHB) and benzene‐1,3,5‐triyl tribenzoate (TBB) were prepared by casting method. Due to the existence of strong intermolecular interaction, the highest in‐plane thermal conductivity of the above films is 1.298 Wm−1 K−1, which is about 65% higher than pure PVA films. Fourier Transform infrared spectroscopy (FT‐IR) and wide‐angle X‐ray diffraction (WXAD) demonstrated that the TBB acts as a thermal bridge to enhance the internal interaction force and make the internal structure more regular. Strong molecular contact forces were demonstrated by mechanical tensile testing. The thermal expansion rate of the system was explored through molecular dynamics. Thermal expansion experiments proved that hydrogen bond can effectively reduce the free volume. Molecular dynamics simulations were also performed in this work. The number and density of hydrogen bonds inside different polymers were calculated, and the phonon thermal transport was quantitatively analyzed. The thermal bridge and intermolecular contact force were discovered to effectively restrict the molecular chain's activity and reduce its free volume. The results of the experiments and molecular dynamics reveal that strong intermolecular interactions and thermal bridges can significantly improve polymer intrinsic thermal conductivity.