Polymer Films Research Articles

Self-oscillating polymeric refrigerator with high energy efficiency.

Electrocaloric1,2 and electrostrictive3,4 effects concurrently exist in dielectric materials. Combining these two effects could achieve the lightweight, compact localized thermal management that is promised by electrocaloric refrigeration5. Despite a handful of numerical models and schematic presentations6,7, current electrocaloric refrigerators still rely on external accessories to drive the working bodies8-10 and hence result in a low device-level cooling power density and coefficient of performance (COP). Here we report an electrocaloric thin-film device that uses the electro-thermomechanical synergy provided by polymeric ferroelectrics. Under one-time a.c. electric stimulation, the device is thermally and mechanically cycled by the working body itself, resulting in an external-driver-free, self-cycling, soft refrigerator. The prototype offers a directly measured cooling power density of 6.5 W g-1 and a peak COP exceeding 58 under a zero temperature span. Being merely a 30-µm-thick polymer film, the device achieved a COP close to 24 under a 4 K temperature span in an open ambient environment (32% thermodynamic efficiency). Compared with passive cooling, the thin-film refrigerator could immediately induce an additional 17.5 K temperature drop against an electronic chip. The soft, polymeric refrigerator can sense, actuate and pump heat to provide automatic localized thermal management.

Dynamic color‐tunable ultra‐long room temperature phosphorescence polymers with photo‐chromism and water‐stimuli response for multilevel anti‐counterfeiting

AbstractDeveloping dynamic color‐tunable ultra‐long room temperature phosphorescence (URTP) polymers with afterglow of over 1 s, photo‐chromism, and multi‐stimuli response for practical anti‐counterfeiting and information security applications is attractive but very challenging. Herein, by doping multicolor phosphorescence pyridinium bromide L block or viologen‐based photo‐chromic V block into polyvinyl alcohol matrixes, the water‐stimuli‐responsive color‐tunable URTP polymer films with afterglow of up to 8 s and the reversible viologen‐based photochromic polymer films have been developed. More significantly, a series of dynamic color‐tunable URTP polymer films with ultra‐long afterglow of over 6 s, photo‐chromism, and water‐stimuli response have been successfully exploited by integrating L and V blocks into one polymer system. Mechanistic investigations have revealed that their photo‐chromism mainly comes from the photo‐generated viologen free radicals. Furthermore, their dynamic multilevel anti‐counterfeiting applications have been demonstrated. These results pave the way to develop smarter multifunctional URTP materials for anti‐counterfeiting and optical sensing.

Tailoring the optical properties of dye–polymer composite films based on polyvinyl alcohol doped with phenol red toward flexible optoelectronic applications

The composite films of polyvinyl alcohol (PVA) incorporating varying concentrations of phenol red (PR) dye were fabricated using the solution casting method. Structural characteristics of the prepared films were explored through XRD and FTIR spectroscopy analyses. The inclusion of PR dye within the PVA matrix induced cross-linking, enhancing the amorphous nature of the doped PVA samples, as evidenced by XRD patterns. In the presence of PR dopants, the FTIR peaks for PVA exhibited altered intensities and increased width, indicating physical interactions between the functional groups of PVA and PR dopants. The impact of PR additives on the optical properties of PVA was investigated across the spectral range of 190–2500 nm. The PVA/phenol red composite demonstrated enhanced UV blocking in the 190–400 nm wavelength range, rendering it suitable for applications such as UV notch filters, including laser blocking filters. The indirect and direct optical band-gaps of PVA polymer films were reduced from 5.20 eV and 5.78 eV to 4.30 eV and 5.28 eV, respectively, with an increase in the PR filling ratio from 0 wt% to 1.8 wt%. The dispersion region of the refractive index was analyzed using the single oscillator model (Wemple-DiDomenico). Calculation and discussion of values such as dispersion and oscillation energies (Ed and Eo), permittivity at infinite frequency (ε ∞), and lattice contribution to the dielectric function (ε L) of PVA/PR composite films were conducted. These advancements position PVA/PR composite films for potential applications in flexible optoelectronic devices, including light-emitting diodes and photodetectors.

Transdermal Delivery of Niacin Through Polysaccharide Films Ameliorates Cutaneous Flushing in Experimental Wistar Rats.

Niacin, an established therapeutic for dyslipidemia, is hindered by its propensity to induce significant cutaneous flushing when administered orally in its unmodified state, thereby constraining its clinical utility. This study aimed to fabricate, characterize, and assess the in-vitro and in-vivo effectiveness of niacin-loaded polymeric films (NLPFs) comprised of carboxymethyl tamarind seed polysaccharide. The primary objective was to mitigate the flushing-related side effects associated with oral niacin administration. NLPFs were synthesized using the solvent casting method and subsequently subjected to characterization, including assessments of tensile strength, moisture uptake, thickness, and folding endurance. Surface characteristics were analyzed using a surface profiler and scanning electron microscopy (SEM). Potential interactions between niacin and the polysaccharide core were investigated through X-ray diffraction experiments (XRD) and Fourier transform infrared spectroscopy (FTIR). The viscoelastic properties of the films were explored using a Rheometer. In-vitro assessments included drug release studies, swelling behavior assays, and antioxidant assays. In-vivo efficacy was evaluated through skin permeation assays, skin irritation assays, and histopathological analyses. NLPFs exhibited a smooth texture with favorable tensile strength and moisture absorption capabilities. Niacin demonstrated interaction with the polysaccharide core, rendering the films amorphous. The films displayed slow and sustained drug release, exceptional antioxidant properties, optimal swelling behavior, and viscoelastic characteristics. Furthermore, the films exhibited biocompatibility and non-toxicity towards skin cells. NLPFs emerged as promising carrier systems for the therapeutic transdermal delivery of niacin, effectively mitigating its flushing-associated adverse effects.

Development of thymol-loaded polymeric films designed as wound dressing materials: Physical, antioxidant, antibacterial, cytocompatibility, and wound healing properties

In the presented study, the potential of thymol-loaded films consisting of pullulan (PUL) and kappa carrageenan (CARR) to be used as wound dressing materials was examined. The films were characterized by FTIR (Fourier transform infrared), TGA (thermogravimetric analysis) and SEM (scanning electron microscopy) analyses. Swelling and hydrolytic degradation behavior, water vapor permeability rate, and mechanical properties, which are important parameters for the films to be evaluated as wound dressing materials, were determined. Antioxidant and antibacterial activities of the films were examined. Additionally, in vitro cytotoxicity and in vitro wound healing activity of the films were evaluated in the L929 fibroblast cell line. The results show that the non-toxic biopolymeric film containing 5 % thymol has the potential to be a promising antioxidant and antibacterial wound dressing, effectively reducing the scratch open area for wound dressing application.

Synthese an der Wasseroberfläche von Vinylen‐Verbundenen Kationischen Zwei‐Dimensionalen Polymerfilmen als Beschichtung für Anion‐Selektive Elektroden

AbstractVinylen verbrückte zwei‐dimensionale Polymere (V‐2DPs) und deren schichtgestapelten kovalent organische Gerüstverbindungen (V‐2D COFs) zeichnen sich durch ihre hohe π‐Konjugation in der Ebene und ihre robuste Struktur als vielversprechnende Kanidaten für energiebezogene Anwendungen aus. Allerdings sind derzeitige syntheisische Ansätze auf die Herstellung von V‐2D COF Pulver beschränkt, welche schlecht prozessierbar sind, was die Integration in Geräte, insbesondere für Membranthechnologien, welche auf dünnen Filmen beruhen erschwert. Im folgenden berichten wir über die neu‐artige Synthese von kationischen 2DPs‐Filmen an der Wasseroberfläche, die über Vinyleneinheiten verbrückt sind (V‐C2DP‐1 und V‐C2DP‐2) mittels Knoevenagel‐Polykondensation, diese dienen als anionenselektive Elektrodenbeschichtung für hochreversible und langlebige Zink‐basierte Dual‐Ionen‐Batterien (ZDIBs). Modellreaktionen und theoretische Modellierung zeigen eine erhöte Reaktivität und Reversibilität der Knoevenagel‐Reaktion an der Wasseroberfläche an. Basierend darauf zeigten wir die 2D Polykondensation hin zu V‐C2DP‐Filmen an der Wasseroberfläche, welche eine weitreichen‐de laterale Größe, anpassbare Dicke und hohe chemischer Stabilität besitzen. Repräsentativ zeigt sich V‐C2DP‐1 als ein vollständig crystalliner und flächen‐orientierter Film mit den in der Ebene liegenden Gitterparametern von a=b≈43.3 Å. Dank der gut definierten katinoischen Funktionalitäten, orientierten 1D‐Kanälen und des sabilen Gerüstes besitzt der V‐C2DP‐1 Film eine herausragende Transportselektivität von Bis(trifluormethansulfon)imid‐anion (TFSI−) (Transferrate, t =0.85) für die Graphitkathode in Hochspannungs‐ZDIBs. Die hohe Selektivität führt zu zusätzlichen TFSI−‐Intercalationsstufen wodurch eine höhere spezifischen Kapazität (von ~83 bis 124 mAh g−1), sowie Zyklusdauer (>1000 Zyklen, 95 % Kapazitätserhaltung) gefördert wird.

D-π-A chromophores based on novel macroacceptors - Fused (azinylmethylene)malononitriles: Linear and nonlinear optical properties in solution and in poled polymer films

D-π-A chromophores based on novel macroacceptors − fused azinylmethylenemalononitriles (fused azine = pyrido [2,3-b]pyrazine, quinoline, quinoxaline and quinoxalin-2-one) − have been synthesized and their linear and nonlinear optical properties in gas, solution and in poled PMMA-based films have been investigated by DFT, UV–vis and second harmonic generation technique. The transition from chromophores with an azine acceptor to ones with azinylmethylenemalononitrile acceptors leads to a 10-fold increase in calculated μβ values. Poled polymer films doped with studied chromophores at 25 wt% load exhibit quadratic nonlinear optical activity with d33 values up to 42 pm/V.

On-Water Surface Synthesis of Vinylene-Linked Cationic Two-Dimensional Polymer Films as the Anion-Selective Electrode Coating.

Vinylene-linked two-dimensional polymers (V-2DPs) and their layer-stacked covalent organic frameworks (V-2D COFs) featuring high in-plane π-conjugation and robust frameworks have emerged as promising candidates for energy-related applications. However, current synthetic approaches are restricted to producing V-2D COF powders that lack processability, impeding their integration into devices, particularly within membrane technologies reliant upon thin films. Herein, we report the novel on-water surface synthesis of vinylene-linked cationic 2DPs films (V-C2DP-1 and V-C2DP-2) via Knoevenagel polycondensation, which serve as the anion-selective electrode coating for highly-reversible and durable zinc-based dual-ion batteries (ZDIBs). Model reactions and theoretical modeling revealed the enhanced reactivity and reversibility of the Knoevenagel reaction on the water surface. On this basis, we demonstrated the on-water surface 2D polycondensation towards V-C2DPs films that show large lateral size, tunable thickness, and high chemical stability. Representatively, V-C2DP-1 presents as a fully crystalline and face-on oriented film with in-plane lattice parameters of a=b≈43.3 Å. Profiting from its well-defined cationic sites, oriented 1D channels, and stable frameworks, V-C2DP-1 film possesses superior bis(trifluoromethanesulfonyl)imide anion (TFSI-)-transport selectivity (transference, t_=0.85) for graphite cathode in high-voltage ZDIBs, thus triggering additional TFSI--intercalation stage and promoting its specific capacity (from ~83 to 124 mAh g-1) and cycling life (>1000 cycles, 95 % capacity retention).

Unraveling the Molecular Weight Dependence of High Magnetic Field to Manipulate the Semiconducting Polymer Molecular Orientation.

The magnetic alignment of molecules, which exploits the anisotropy of diamagnetic susceptibility, provides a clean and versatile approach to the structural manipulation of semiconducting polymers. Here, the magnetic-alignment dynamics of two molecular-weight (MW) batches of a diketopyrrolopyrrole (DPP)-based copolymer (PDVT-8) were investigated. Microstructural characterizations revealed that the magnetically aligned, high-MW (Mn = 53.7 kDa) PDVT-8 film exhibited a higher degree of backbone chain alignment and film crystallinity compared with the low-MW (Mn = 17.6 kDa) PDVT-8 film grown via the same magnetic alignment method. We found that as the MW increases, the degree of preaggregation of the polymer molecules in solution significantly increases and the aggregation mode changes from H-aggregation to J-aggregation through a cooperative assembly mechanism. These events improved the responsiveness of high-MW polymer molecules to magnetic fields. Field-effect transistors based on the magnetic aligned high-MW PDVT-8 films exhibited a 6.8-fold increase in hole mobility compared to the spin-coated films, along with a mobility anisotropy ratio of 12.6. This work establishes a significant correlation among chain aggregation behavior in solution, polymer film microstructures, magnetic responsiveness, and carrier transport performance in donor-acceptor polymer systems.

Ammonia-trapping multilayer polymer urease film amplifier coated surface plasmon resonance sensor for ultra-sensitive urea detection

In this paper, we have developed a new urea signal amplification technology based on a multilayer urease polymer film self-assembly structure for the first time, enabling the realization of ultra-accurate urea optical detection. We demonstrate the effectiveness of this technique based on surface plasmon resonance (SPR) platform. When the urea signal amplifier is combined with SPR sensors, multilayer urease polymer film contacts with urea molecules, the urea molecules are oxidated into NH3 and CO2, causing the pH increase, which weakens the electrostatic interaction between different polymer layers and induces the RI reduction of the multilayer urease film, thereby causing the shift of the SPR spectrum. Experiment results confirm that urea sensitivity has been improved 12-fold, and the limit of detection (LOD) has been optimized to less than 10−3 mmol/L. Furthermore, the anti-interference has been improved 22.8-fold and is kept even the interference signal strength increases by 100 times. Moreover, multilayered urease polymer leads to the increase of urease on the sensor surface, thus expanding the detection range of urea by 3.5 times. This provides a new way to solve the contradiction between high sensitivity and large measurement range of optical fiber biosensor. Importantly, the concept of using enzyme-loaded polymer films for signal amplification can be adapted for the detection of various other biomolecules by replacing the enzyme with a specific recognition element for the target molecule. This opens doors for developing highly sensitive and specific biosensors for diverse applications in healthcare, environmental monitoring, and food safety.

Design and research on sequentially controlled magnetic-driven actuators with high stiffness by changing local EGaIn structural density

Magnetic-driven actuators (MDAs) are attracting increasing attention due to fast response and harmless interaction with humans. However, due to their low stiffness and difficulties in sequential magnetic control, MDAs are difficult to complete high-load tasks, and overcoming these obstacles can enable them to be exploited for a wide range of novel applications. In this work, sequentially controlled MDAs (SC-MDAs) with high stiffness were prepared by embedding a polydimethylsiloxane/liquid metal (PDMS/EGaIn) heating layer between magnetic memory polymer (MSMP) films. The variation of EGaIn structural density between different regions leads to temperature discrepancies, resulting in selective activation of specific regions for sequence control. The modulus of the optimized MSMP film at room temperature is 2.21 GPa, which exceeds that of other materials (about 1 MPa) by three orders of magnitude, demonstrating a substantial increase in stiffness. When the content of NdFeB is adjusted to 80 wt%, driving performance is adjusted by optimizing the length-thickness ratio of SC-MDAs. Each claw of the mechanical gripper exhibits a remarkable increase in load capacity, being able to carry 54 times its own weight, which is significantly higher compared to actuators made from other materials (about its weight). A hand-like actuator realizes the sequential control deformation by combining “fingers” with different heating properties.

Mechanical properties of polymer modified mortars using polymer latexes with varied glass transition temperature and surface charges

Mechanical properties of polymer modified mortar (PMM) were investigated using self-synthesized polymer latexes with varied glass transition temperature (Tg) and colloidal surface charges to build correlations between the mechanical properties of PMMs and the intrinsic properties of the polymers. Generally, compressive strength and elastic modulus of mortar are decreased, but ductility and toughness are enhanced by incorporation of the polymers. Impacts of the lower Tg polymers on the mechanical properties of PMMs are more pronounced. With increasing polymer content, flexural and tensile strength of mortar first increase and then decrease when using low Tg polymers that form continuous film during hardening of the mortars, while steadily decrease in the case of high Tg polymers that exist as individual particles in the hardened PMMs. For the high Tg polymer modified mortars, it is interestingly found that a subsequential heat treatment effectively promotes the film formation of the polymers in the hardened PMMs and thus greatly increases their flexural and tensile strength. This indicates that polymer film formation is essential to the enhancement of the PMMs, because the polymer films play a crack-bridging effect while the individual particles cannot do such job. The high Tg polymers lead to higher tensile strength of PMMs after heat treatment due to the higher inherent strength of the polymer film. Higher colloidal surface charge benefits the mechanical properties of the PMMs by (1) promoting a more homogenous polymer distribution in the hardened PMMs and/or (2) improving the bonding between the polymer phase and cement hydrates.

Infrared spectral features of the charge carriers in nickel salen polymeric complexes

A series of the polymeric complexes (PCs) of nickel(II) with N2O2 Schiff base ligands have been studied by in situ Fourier Transform Infrared (FTIR) spectroelectrochemistry. The molecular structure of the metal-salen complexes as starting materials for the polymer synthesis was modulated by various substituents in the phenolate moieties and diimine bridge. Two groups of the infrared-active vibration (IRAV) bands are obtained in the spectra depending on the oxidation level of the polymers. The assignment of the main IRAV bands was carried out and the electrochemically generated charge carriers were determined. Analysis of the spectroscopic features observed in the mid and near IR region provides information on the charge distribution within the polymer film.

Facile Synthesis of Cu-Doped TiO2 Particles for Accelerated Visible Light-Driven Antiviral and Antibacterial Inactivation.

In this work, we present a facile and scalable hydrolysis-based route for the synthesis of copper-doped TiO2 particles for highly effective light-activated antiviral and antibacterial applications. The performance of the synthesized Cu-doped TiO2 particles is then evaluated using solution-phase antimicrobial photodynamic inactivation assays. We demonstrate that the Cu-doped TiO2 particles can successfully inactivate a wide range of pathogens with exposure to light for 90 min, including bacteria ranging from methicillin-resistant Staphylococcus aureus (99.9999%, ∼6 log units) to Klebsiella pneumoniae (99.93%, ∼3.3 log units), and viruses including feline calicivirus (99.94%, ∼3.4 log units) and HCoV-229E (99.996%, ∼4.6 log units), with the particles demonstrating excellent robustness toward photobleaching. Furthermore, a spray-coated polymer film, loaded with the synthesized Cu-doped TiO2 particles achieves inactivation of methicillin-resistant S. aureus up to 99.998% (∼4.8 log units). The presented results provide a clear advance forward in the use of metal-doped TiO2 for aPDI applications, including the scalable synthesis (kg/day) of well-characterized and robust particles, their facile incorporation into a nontoxic, photostable coating that may be easily and cheaply applied to a multitude of surfaces, and a broad efficacy against drug-resistant Gram-positive and Gram-negative bacteria, as well as against enveloped and nonenveloped viruses.

In situ fabrication of porous polymer films embedded with perovskite nanocrystals for flexible superhydrophobic piezoresistive sensors

The application of pressure sensors based on perovskite in high-humidity environments is limited by the effect of water on their stability. Endowing sensors with superhydrophobicity is an effective strategy to overcome the issue. In this work, MAPbBr3/Polyvinylidene Fluoride-TFSI composite was prepared by a one-step in-situ strategy to form a flexible superhydrophobic pressure sensor, which exhibited a contact angle of 150.25°. The obtained sensor exhibited a sensitivity of 0.916 in 1 kPa, a detection limit of 0.2 Pa, a precision of 0.1 Pa, and a response/recovery of ∼100 ms, along with good thermal stability. Through density functional theory calculations, it is revealed that the formation of the porosity is attributed to the interaction between the polymer and EMIM TFSI, which further leads to superhydrophobicity. And, the perovskite structure is easy to change under pressure, affecting the carrier transport and electrical signals output, which explains the sensing mechanism. In addition, the sensor performed well in monitoring facial expression, pulse, respiration, finger bending, and wind speed ranging from 1 m/s to 6 m/s. With both the Linear Regression and the Random Forest algorithm, the sensor can monitor the wind speed with an R2 greater than 0.977 in 60 tests.

Ultrathin alternating multilayered silver nanowire-coated electrospinning films for excellent electromagnetic interference shielding and robust mechanical properties

Developing an ultra-thin flexible polymer film with simultaneously excellent electromagnetic interference (EMI) shielding performance and satisfactory mechanical property is still urgently demanded but challenging for integrated and miniaturized electronics. Herein, alternating multilayered silver nanowire-coating polyvinyl alcohol/ferroferric oxide@silver nanowires (PVA/Fe3O4@AgNW) composite films were successfully fabricated through spraying AgNWs on electrospinning PVA/Fe3O4 films, followed by hot pressing the alternately stacked monolayer PVA/Fe3O4 and PVA/Fe3O4@AgNW films in total of 6 layers. Stemming from superior conductive AgNW networks, alternating multilayered PVA/10-Fe3O4@10-AgNW composite film exhibits the prominent electrical conductivity of 1.5 × 105 S/m. Noteworthily, 6-layered PVA/10-Fe3O4@10-AgNW composite film with a thickness of 30 μm displays excellent EMI shielding effectiveness (SE) of 80.8 dB, on account of the unique alternating multilayered architectures and synergistic effect of conductive AgNWs and magnetic Fe3O4. Furthermore, 6-layered PVA/10-Fe3O4@10-AgNW film possesses satisfactory tensile strength (16.7 MPa) as well as superb flexibility (The fracture strain is 200.6 %). This effort sheds a new avenue for ultrathin flexible electrospinning films with both high EMI SE and remarkable flexibility, which has potential application in intelligent, wearable, and portable electronics.

Facile Preparation of Stable NiII‐ and CoII‐tetraaminophthalocyanine Electropolymers for Highly Efficient Heterogeneous Carbon Dioxide Reduction

This study focused on preparation of stable polymer films of NiII‐ and CoII‐tetraaminophthalocyanines, p‐NiTAPc and p‐CoTAPc, respectively, for highly efficient heterogeneous electrochemical carbon dioxide (CO2) reduction in a flow electrolysis cell. Major development represented in this work was fabrication of p‐NiTAPc and p‐CoTAPc films via electropolymerization of their corresponding monomers on carbon‐based substrates without using binder or conducting additive materials to obtain efficient gas diffusion electrodes (GDEs) for scalable, productive and selective CO2‐to‐CO conversion. The target polymers were characterized by UV‐visible spectrophotometry, attenuated total reflection‐Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectroscopy and cyclic voltammetry. According to controlled potential electrolysis and gas chromatography, p‐NiTAPc‐catalyzed CO2 reduction at –0.99V vs. reversible hydrogen electrode (RHE) gave 953 mL of CO in a period of 16 hours with current density and Faradaic efficiency (FE) of 109±1 mA·cm‐2 and 99±2%, respectively. A p‐CoTAPc‐modified GDE exhibited superior catalytic performance to the case of p‐NiTAPc in terms of catalyst stability and CO productivity by performing the continuous CO2 reduction at the potential of –1.10 V vs. RHE for up to 41 hours and affording almost 3 times higher amount of CO with the current density of 161±5 mA/cm2 and 95±2% FE.

Development of PVA/sodium alginate incorporated with histidine capped silver nanoparticles for food packaging application

AbstractPackaging is a growing field of interest, and the use of nanotechnology is accelerating its expansion. The study reports the fabrication of poly(vinyl alcohol) (PVA) blended sodium alginate (SA) and incorporated with different ratios of histidine‐capped silver (H‐AgNPs) nanoparticle films. Fabrication of PVA/SA/H‐AgNPs films was confirmed with the surface plasmon resonance (SPR) band denoted AgNPs presence between 400 and 420 nm measured by UV–Vis absorption spectroscopy. The characteristics of the polymeric biocomposite films were significantly altered by different ratios of AgNPs. The interaction of PVA/SA and PVA/SA with AgNPs was analyzed by using FT‐IR analysis. The degree of crystallinity was increased upon increasing the concentration of H‐AgNPs as confirmed by XRD measurements. The homogeneity of dispersion and surface morphology of samples were studied by FESEM. The addition of H‐AgNPs in the polymeric film increased the surface roughness of the polymeric film confirmed by AFM analysis. The contact angle of the PVA/SA blend matrix was observed to be 46.97°, and with the incorporation of AgNPs ranging from 3%, 5%, and 7% to the blend matrix, the contact angle of the nanocomposite films in increasing hydrophobic order was 60.53°, 83.57°, and 96.20°, respectively. The incorporation of AgNPs also demonstrates that the PVA/SA blend matrix has desirable thermal stability. The improved qualities were due to H bonding between PVA, SA, and H‐AgNPs, in which molecules contact strongly with one another. Furthermore, the PVA/SA/H‐AgNPs showed significant antibacterial activity against both Gram‐positive (G+) strains (Staphylococcus aureus) and Gram‐negative (G−) strains (Escherichia coli) bacterial infections. The findings of this research indicate that the PVA/SA/H‐AgNPs fabricated composite films considerable for applications in food packaging.

Fabrication of Self‐Wrinkling Polymer Films with Tunable Patterns through an Interfacial‐Fuming‐Induced Surface Instability Process (Small 19/2024)

Fabrication of Self‐Wrinkling Polymer Films with Tunable Patterns through an Interfacial‐Fuming‐Induced Surface Instability Process (Small 19/2024)

Comparison of vacuum ultraviolet irradiation and oxygen plasma treatment as pretreatment for copper seed layer on cycloolefin polymer

This study explores the factors governing the peel strength characteristics between a cycloolefin polymer (COP) film and a copper plating layer with a copper seed layer, for applying to antenna circuits in 6 G communications. The peel strength depended on the surface modification methods as pretreatment for copper seed layer formation: vacuum ultraviolet (VUV) irradiation and oxygen plasma treatment. VUV irradiation induced a modified layer with brittleness on the COP surface, leading to substrate failure. Conversely, oxygen plasma treatment formed a quite thin modified layer and facilitated Cu2O formation by bonding functional groups on the topmost COP surface with copper in the seed layer at the interface between the COP film and the copper plating layer, resulting in interface failure rather than substrate failure. Therefore, enhancing peel strength involves preventing the formation of a modified layer on the surface and generating a significant quantity of functional groups on the topmost surface.