Composite Films Research Articles

Rapid in situ formation of κ-carrageenan-carboxymethyl chitosan-kaolin clay hydrogel films enriched with arbutin for enhanced preservation of cherry tomatoes

Food waste resulting from perishable fruits and vegetables, coupled with the utilization of non-renewable petroleum-based packaging materials, presents pressing challenges demanding resolution. This study addresses these critical issues through the innovative development of a biodegradable functional plastic wrap. Specifically, the proposed solution involves the creation of a κ-carrageenan/carboxymethyl chitosan/arbutin/kaolin clay composite film. This film, capable of rapid in-situ formation on the surfaces of perishable fruits, adeptly conforms to their distinct shapes. The incorporation of kaolin clay in the composite film plays a pivotal role in mitigating water vapor and oxygen permeability, concurrently bolstering water resistance. Accordingly, tensile strength of the composite film experiences a remarkable enhancement, escalating from 20.60 MPa to 34.71 MPa with the incorporation of kaolin clay. The composite film proves its efficacy by preserving cherry tomatoes for an extended period of 9 days at 28 °C through the deliberate delay of fruit ripening, respiration, dehydration and microbial invasion. Crucially, the economic viability of the raw materials utilized in the film, coupled with the expeditious and straightforward preparation method, underscores the practicality of this innovative approach. This study thus introduces an easy and sustainable method for preserving perishable fruits, offering a cost-effective and efficient alternative to petroleum-based packaging materials.

Development of pH Indicator Composite Films Based on Anthocyanins and Neutral Red for Monitoring Minced Meat and Fish in Modified Gas Atmosphere (MAP)

Development of pH Indicator Composite Films Based on Anthocyanins and Neutral Red for Monitoring Minced Meat and Fish in Modified Gas Atmosphere (MAP)

Effects of germanium content on the optical properties of GeO2-based organic-inorganic composite films doped with azobenzene

Organic-inorganic composite materials have great applications in integrated optics due to their good optical performance. In this study, GeO2-based organic-inorganic composite films doped with azobenzene were prepared by combining the solgel technique and the spin-coating method. The optical waveguide properties including the refractive index and film thickness and the optical response properties of the composite films with different germanium contents have been investigated. The results indicate that the refractive index of the film increases, but the film thickness decreases as the germanium content increases. The composite film with 0.2 mol of germanium exhibits the best optical response properties. Further, the optical switching characteristics of the optimal composite film shows good stability and reversibility. The photochemical and structural properties of the film were also investigated by using Fourier transform infrared spectroscopy and thermo-gravimetric analysis. Finally, hexagonal microlens arrays were built in the film by using the UV nanoimprint technique, resulting in neatly arranged structures with good optical imaging performance.

Preparation and Properties of Dye-Sensitizing Graphene/TiO2 based Photocatalytic Composite Film by Electrospray Method

Preparation and Properties of Dye-Sensitizing Graphene/TiO2 based Photocatalytic Composite Film by Electrospray Method

Multimode interference methane sensor based on a ZIF-8/PDMS composite film.

A multimode interference methane sensor based on a ZIF-8/PDMS composite film is proposed. The sensing principle is that the refractive index of the ZIF-8/PDMS composite film changes when it adsorbs methane, leading to a measurable optical path difference during the coupling of the cladding higher-order modes and the fundamental mode in the multimode interference fiber (MMI). The environmental methane concentration is then detectable by detecting the wavelength shifts of the interference peaks in the resulted spectrum. Through simulations and experiments aimed at enhancing sensor sensitivity, we optimized three parameters within the sensor structure: the length of the Tapered Single-Mode Fiber (TSMF), the composite film thickness, and the TSMF taper diameter. The experimental results indicate that the sensor's sensitivity reaches a maximum of 0.231 nm%-1. Additionally, the sensor exhibits excellent structural stability and measurement repeatability. The response time is as short as 40 s, and the recovery time ranges between 3 and 5 min. The proposed multimode interferometric methane sensor based on the ZIF-8/PDMS composite film has great potential to support highly sensitive methane concentration detection in many applications.

Recent Progress and Challenge in Metal–Organic Frameworks for Lithium–Sulfur Battery Separators

AbstractThe separators used in lithium‐sulfur (Li–S) batteries play a crucial role in their cycling performance and safety. Current commercial separators lack the ability to efficiently regulate polysulfide shuttling and are prone to thermal runaway at high temperatures. Recent studies have shown that multifunctional separators can boost the electrochemical performance and safety of Li–S batteries. Metal–organic frameworks (MOFs) have emerged as promising materials for modifying separators due to their large specific surface areas and highly ordered tunable nanopores. Herein, this review focuses on the advancements in developing MOFs, their derivatives, and MOFs‐based composites as separator coatings to address the shortcomings of Li–S batteries. The mechanisms behind these modified separators, designed to inhibit lithium polysulfide shuttling and lithium dendrite growth, are discussed, emphasizing the relationship between the structure and electrochemical performance. The impact of these modified separator coatings on battery safety is also explored, aiming to design suitable composite films for high‐safety Li–S batteries. Furthermore, future perspectives are outlined to guide practical applications and overcome the remaining challenges associated with MOFs‐modified separators.

Hybrid Ethylcellulose Polymeric Films: Ag(I)-Based Components and Curcumin as Reinforcing Ingredients for Enhanced Food Packaging Properties.

Bio-active ethylcellulose (EC) polymeric films have been obtained by incorporating curcumin (curc) and Ag(I)-based compounds, known for their antioxidant and antimicrobial activity, respectively, within the polymeric matrix. The recently reported Ag(I) coordination polymer, in both its structural forms (α-[(bpy)Ag(OTf)]∞ and β-{[(bpy)Ag][OTf]}∞), and the [(bpy)Ag(OTf)]∞-curc polymeric co-crystal (bpy = 2,2'-bipyridine; OTf = trifluoromethanesulfonate) have been selected as Ag(I) species. The hybrid composite films have been prepared through the simple solvent casting method and characterized through Powder X-Ray Diffraction (PXRD), Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM), UV-vis spectroscopy. The deep investigation of the film samples highlighted the non-inert behaviour of EC towards these specific active ingredients. Antimicrobial tests showed that EC films embedding the Ag(I)-based compounds present good antimicrobial performance, in particular against Staphylococcus aureus, used as a model of Gram-positive bacteria. In addition, Silver migration tests, performed on the Ag(I)-incorporating EC films, evidenced low values of silver release particularly in the case of the EC films incorporating [(bpy)Ag(OTf)]∞-curc.

Chitin/calcium carbonate complex microparticles and their effects on polylactic acid composite films

Chitin/calcium carbonate complex microparticles and their effects on polylactic acid composite films

Biodegradation of Lignocellulose-Polyester Composite Films in Freshwater and Seawater Conditions

Biodegradation of Lignocellulose-Polyester Composite Films in Freshwater and Seawater Conditions

Recent progress in polyvinyl alcohol (PVA)/nanocellulose composite films for packaging applications: A comprehensive review of the impact on physico‐mechanical properties

AbstractAs society advances, the demand for innovative and sustainable food processing techniques and materials has grown significantly. The food industry, especially the food packaging sector, faces the challenge of developing cost‐effective and sustainable packaging materials to meet consumers' increasing demands. One promising solution for this is the use of biodegradable polymers such as polyvinyl alcohol (PVA), but standalone PVA cannot meet the required properties of packaging materials. The use of nanocellulose (NC) as fillers has been intensively studied recently. This review article provides a comprehensive overview of existing studies focusing on the preparation of PVA/NC composite films for packaging applications. The effects of NC loading on the physico‐mechanical properties of these films, including tensile strength, elongation, water absorption/swelling behavior, barrier properties, and optical properties, have been thoroughly examined. Overall, the general findings suggest that the reinforcement of NC in the PVA polymer matrix leads to improvements in the films' properties. Specifically, the addition of NC enhances tensile strength, reduces O2, CO2, and water vapor transmission rates, and decreases the films' propensity to absorb moisture or swell under wet conditions. However, it is important to note that the presence of NC compromises the optical properties of the films by reducing transparency, and the NC content beyond threshold level reduces the feasibility of the composite film. By synthesizing these findings, this review underscores the potential of PVA/NC composite films as promising materials for packaging applications. Moving forward, further research efforts are warranted to optimize the formulation and processing of these composite films to strike a balance between mechanical strength and optical clarity, thus advancing their practical utility in the packaging industry.

Phosphor‐Loaded Triboelectric Film‐Based Multipurpose Triboelectric Nanogenerators for Highly‐Efficient Energy Harvesting, Sensing, and Self‐Illumination Applications

AbstractA novel approach is proposed for combining phosphor materials with triboelectric nanogenerators (TENGs) for mechanical energy harvesting and illumination applications. For this purpose, strongly reddish‐orange‐emitting Ba0.5Sr0.5Nb2O6:0.25 mol Eu3+ (BSNb:0.25Eu) phosphor materials are synthesized. The photoluminescence properties of the synthesized BSNb:0.25Eu are analyzed. The synthesized BSNb:0.25Eu is utilized as a dielectric filler inside a polydimethylsiloxane polymeric film due to its high dielectric properties to improve the overall dielectric properties of the composite film (CF). TENG devices are fabricated using phosphor‐loaded CFs as the tribonegative layer, transparent polyvinyl alcohol as the tribopositive layer, and aluminum as the conductive electrode. All the TENGs operate in a contact‐separation mode, and the highest electrical output is attained by optimizing the phosphor filler concentration in the CF. The optimized TENG exhibits excellent stability in long‐term operational tests, under varying harsh ambient temperatures. Indium tin oxide sputtered on both triboelectric films as an electrode and combined with a transparent hard substrate to obtain a fully transparent TENG. A self‐illuminating TENG (SI‐TENG) is fabricated by integrating near‐ultraviolet light‐emitting diodes between two identical TENGs. The SI‐TENG can harvest the mechanical energy available in the surrounding environment and illuminate it as a light source. Additionally, the proposed phosphor‐loaded polymer films can be employed for optical thermometry and mechanical energy harvesting via SI‐TENG on a large scale.

Microstructure, rheology and freeze-thaw behavior of double (W1/O/W2) emulsions prepared with palm oil: Effect of Tween 80/sodium caseinate ratio

The objective was to study the effect of the variation of Tween 80/sodium caseinate ratio on the microstructure, rheology and freeze-thaw behavior of double (W1/O/W2) emulsions prepared with palm oil. Particularly, the impact of the composition of the outer interfacial film on partial coalescence and retention of inner water droplets was investigated. Partial coalescence was restrained in the emulsion prepared with sodium caseinate only, because aggregation of oil globules was prevented due to electrostatic and steric repulsions and a resistant interfacial film. The inclusion of Tween 80 produced competitive adsorption of emulsifiers, promoting partial coalescence and increasing the elastic and viscous modules of the system. A higher Tween 80 proportion led to lower retention of inner water droplets after cold storage, attributed to the formation of smaller oil globules and a thinner interfacial film. A cooling-heating-cooling cycle was applied by differential scanning calorimetry, showing that a higher oil globule aggregation degree led to higher retention of inner water droplets during freezing and higher release of inner water droplets during thawing. The findings expand the knowledge regarding the influence of the composition of the outer interfacial film on both partial coalescence and retention of inner water droplets in W1/O/W2 emulsions.

Characterization, Dielectric Analysis and Thermal Properties of Novel Flexible Polymer Composite Films

In this work, mixtures of polypyrrole (PPy) and iron oxide (Fe2O3) are synthesized using oxidative chemical polymerization process to create a novel flexible PET/(PPy-Fe2O3) composite films. The films were characterized by different methods as FTIR, SEM, XRD and TGA to prove the efficient manufacturing of the composite. The dielectric performance measurements were done at frequency of 20 Hz to 6 MHz for the polymer PET and the composite (PPy-Fe2O3)/PET with varying concentrations of Fe2O3. Moreover, to reveal the characteristics of the fabricated composite, the contact angle, the work of adhesion, surface energy of the composite PET/(PPy-Fe2O3) films were considerably determined. The SEM results support the deposition of PPy-Fe2O3 composite on the PET surface. The water contact angle drops from 78.32° for PET to 40.11° for PET/6%(PPy-Fe2O3), while the dispersive free energy raised from 23.9 mJ m−2 to 43.7 mJ m−2and the polar free energy rises from 8.9 mJ m−2 to 22.3 mJ m−2. The concentration of Fe2O3 increased the surface features of the samples, according to the obtained results. At frequency of 100 Hz, the dielectric constant enhanced from 18 for PET to 923 for the PET/6%(PPy-Fe2O3), and the dielectric loss improved from 24 to 9231, while the energy density improved fromm 7.9 × 10−5 J/m3 for PET to 408 × 10−5 J m−3. The TGA results show marginal modifications in thermal stability after deposition the PPy/Fe2O3 on the PET film. The obtained data showed the dielectric characteristics of the PET/(PPy-Fe2O3) were improved respect to polymer PET, to can be applied the fabricated composite in storage devices and capacitors.

A capacitive humidity sensor based on nanodiamond/silver nanoparticles (ND/Ag) nanocomposite with high stability and rapid response for respiratory monitoring

In this work, a high-performance capacitive humidity sensor based on nanodiamond/silver nanoparticles (ND/Ag) nanocomposite is proposed. The influence of silver nanoparticles with different content in nanodiamond is investigated, and the optimum ratio of 5 wt% Ag in the composite shows the maximum humidity sensing performance, which is three times than that of the pure nanodiamond based humidity sensor. Moreover, the proposed sensor exhibits a superior repeatability, ultrafast response time (<2 s) and recovery time (<1 s). More importantly, the sensor can maintain a good repeatability and rapid response speed when exposure to high humidity for a long time, demonstrating the excellent stability of the proposed sensor. Furthermore, complex impedance spectroscopy was applied to account for the underlying sensing mechanisms of the ND/Ag composite film humidity sensor. Finally, we design a circuit to realize non-contact breathing control by using the fabricated humidity sensor, which demonstrate that the fabricated humidity sensor could be applied to some auto-control systems by human-breath. This work demonstrated that ND/Ag composite film is an ideal candidate material for constructing high-performance humidity sensors for respiratory applications.

Universal Dimensionality of Ferroelectric Domain Walls in Ultrathin Films

AbstractThe dimensionality of dynamic interfaces—domain walls (DWs) —is greatly influenced by symmetry and physical dimensions, irrespective of the microscopic details of the system. To address this fundamental question for the ferroelectric model system, the DW scaling criticality and dimensionality is investigated in ultrathin films of varied ferroelectric materials, compositions, and electrode–ferroelectric interfaces, grown on nominally flat and vicinal substrates. In spite of significant variations among ferroelectric systems, the observed prevalence of 1D DWs is consistent with a random bond disorder, elucidated through a scenario of 2D nucleation and growth‐driven DW creep. These findings highlight the thickness size‐dominated universal behavior of ferroelectric DWs, uncovering fascinating prospects for dimensionally engineered DW‐based nanoelectronics.

Synthesis, Structural Investigations, and Dielectric Properties of Irradiated Flexible Polymeric Composite Films

In this research, the casting solution manufacturing approach was used to mix polyvinyl alcohol (PVA) and copper oxide (CuO) to create the composite (PVA/CuO). X-ray diffraction analysis and Fourier transform infrared spectroscopy were applied to record the successful fabrications of the composites. Next, argon ion beams at fluencies of 2.5 × 1017, 5 × 1017, and 7.5 × 1017 ions.cm−2 were used to irradiate the composites. In frequencies of 50 Hz to 6 MHz, the dielectric characteristics of PVA/CuO were modified by the ion irradiation. The dielectric constant was enhanced from 39 for unmodified PVA/CuO to 356 for the irradiated composite by 7.5 × 1017 ions.cm−2, and the conductivity changed from 0.05 × 10−6 S cm−1 to 2.9 × 10−6 S cm−1. However, the potential barrier decreased from 0.24 eV for PVA/CuO to 0.21, 0.16, and 0.15 eV, respectively, for 2.5 × 1017, 5 × 1017, and 7.5 × 1017 ions.cm−2, and the relaxation time decreased from 9.36 × 10−8 sec for PVA/CuO, to 6.58 × 10−8 sec for 7.5 × 1017 ions.cm−2. The results indicate that the irradiated PVA/CuO nanocomposite can be used in a number of devices such as capacitors and batteries.

Preparation of ternary composite film TiO2/Fe2O3/Ti3C2 for photoelectrocatalytic degradation of organic pollutants and bacterial inactivation in water

Global water pollution is a serious problem, and photoelectrocatalytic technology is expected to be a new path to solve it. In this study, a ternary composite TiO2/Fe2O3/Ti3C2 photoanode was synthesized by hydrothermal, water bath, and spin-coating methods for the photoelectrocatalytic degradation of pollutants and disinfection in water. The results showed that the composite film was capable of degrading 96.74 % of MB solution within 120 min and killing 99.43 % of E. coli and 100.00 % of S. aureus within 30 min. Furthermore, the MB degradation efficiency remained nearly constant throughout the 35th cyclic photoelectrocatalytic reaction, demonstrating the adequate stability of the photoanode. The outstanding performance of the film is attributed to (1) the large specific surface area due to the unique structure of composite, (2) low surface-interface resistance and improvement of photogenerated carrier separation and migration because of heterojunction structure and co-catalyst Ti3C2 with high conductivity. It is also proved that the four radicals ·O2-, ·OH, ∙Cl, ∙ClO play a role in the system. This study provides a practical direction for designing future photocatalytic materials and advancing the treatment of pollutants in water.

Preparation and Properties of Polyaniline/Hydroxypropyl Methylcellulose Composite Conductive Thin Films.

In this work, a chemical grafting polymerization method was employed to synthesize EHPMC-g-PANI self-supporting films. Polyaniline (PANI) was grafted onto hydroxypropyl methylcellulose (HPMC) modified with epichlorohydrin (EPHMC) to obtain an EHPMC-g-PANI aqueous dispersion, which was subsequently dried to form the self-supporting films. The introduction of HPMC, with its excellent film-forming ability and mechanical strength, successfully addressed the poor film-forming ability and mechanical properties intrinsic to PANI. Compared to in situ polymerized HPMC/PANI, the EHPMC-g-PANI exhibited significantly improved storage stability. Moreover, the fabricated EHPMC-g-PANI films displayed a more uniform and smoother morphology. The conductivity of all the films ranged from 10-2 to 10-1 S/cm, and their tensile strength reached up to 36.1 MPa. These results demonstrate that the prepared EHPMC-g-PANI holds promising potential for applications in various fields, including conductive paper, sensors, and conductive inks.

A robust, eco-friendly, and biodegradable cellulose nanofiber composite film for highly effective formaldehyde removal at room temperature

Formaldehyde (HCHO) poses a significant threat as a common indoor air pollutant, leading to various health issues. However, effectively addressing HCHO removal at room temperature remains a considerable challenge. This paper presents the preparation of a robust, eco-friendly, and biodegradable composite cellulose nanofiber film, incorporating CeO2-Ag@MnO2 catalysts and TEMPO-oxidized cellulose nanofiber (TOCNF), for high-efficiency HCHO removal at room temperature. A CeO2-Ag@MnO2 ternary catalyst with a core–shell structure was constructed to enhance the catalytic oxidation activity and stability. This structure increased the number of active sites on the catalyst surface and enhanced the interfacial synergistic effect of Ce-Ag-Mn. The TOCNF physically adsorbed HCHO in the composite film, while the catalyst oxidized it to CO2 and water. The composite films, particularly those with 20 wt% CeO2-Ag@MnO2 catalyst, exhibited high HCHO removal rates of 91.2 % at 20 °C and 99.6 % at 60 °C. Furthermore, the TOCNF/20 CAM composite films demonstrated excellent mechanical properties and degradability. This composite film offers an efficient and eco-friendly solution for the catalytic oxidation of HCHO at room temperature.

2D ordered porous VO2-based composite film with enhanced thermochromism performance and high stability for smart windows

Thermochromic vanadium dioxide (VO2) can autonomously adjust near-infrared light transmittance in response to the external temperature changes, offering a significant reduction in building energy consumption when applied it in smart window. However, it is a big challenge for simultaneous optimization of visible light transmittance, solar modulation ability, and stability in VO2. To address such a big challenge, this study successfully prepared a 2D ordered porous VO2@Zn3V3O8 composite film. The as-obtained film exhibits exceptional optical performance with a visible light transmittance (Tlum) of 62.75 % and the solar modulation ability (ΔTsol) of 10.62 %, based on the anti-reflective effects of porous structure and the localized surface plasma resonance (LSPR) absorption of independently distributed VO2 nanoparticles. In addition, the composite structural film showcases excellent environmental durability that 80 % of ΔTsol could be retained after 30 days aging under the conditions of 50 % humidity and 100 °C. This work propels the practical application of VO2 smart windows and offers valuable insights for the design of composite structures.