Polymer Films Research Articles

Highly Moisture-Resistant Flexible Thin-Film-Based Triboelectric Nanogenerator for Environmental Energy Harvesting and Self-Powered Tactile Sensing.

Triboelectric nanogenerator (TENG) has been demonstrated as a sustainable energy utilization method for waste mechanical energy and self-powered system. However, the charge dissipation of frictional layer materials in a humid environment severely limits their stable energy supply. In this work, a new method is reported for preparing polymer film as a hydrophobic negative friction material by solution blending poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinyl chloride (PVC), doping with titanium dioxide (TiO2) nanoparticles, and further surface patterning modification. The P-TENG composed of the PVDF-HFP/PVC/TiO2 composite film with optimized hydrophobic performance (WCA = 124°) achieved an output voltage of 235 V and a short-circuit current of 35 μA, which is approximately three times that of the bare PVDF-HFP-based TENG. Under charge excitation, the transferred charge of the P-TENG can reach 35 nC. When the external load resistance is 5.5 MΩ, the output peak power density can reach 1.4 W m-2. Meanwhile, the hydrophobic surface layer with a rough surface structure enables the device to overcome the influence of water molecules on charge transfer in a humid environment, quickly recover, and maintain a high output. The P-TENG can effectively monitor finger flexibility and strength and realize real-time evaluation of the exercise state and hand fatigue of the elderly and rehabilitation trainers. It has broad application prospects in self-powered intelligent motion sensing, soft robotics, human-machine interaction, and other fields.

Development of Printed Pouch Film and Flexible Battery

This study investigates the properties of various adhesives and assesses the effects of the coating and drying conditions of aluminum surface treatment agents on adhesion strength and chemical resistance. The adhesion between aluminum and the polymer film is improved through the application of a surface treatment agent to the aluminum surface. This study examines the initial adhesive strength of a manufactured pouch film with respect to the drying temperature and time and evaluates its adhesive strength in the presence of moisture. The results indicate that the residual moisture on the aluminum surface weakens the adhesive strength and significantly affects electrolyte resistance. A noticeable reduction in strength was observed after water spraying, when the drying temperature and time were relatively low during the initial strength measurement. Among the adhesives used for aluminum and CPP lamination, olefin adhesives exhibit less susceptibility to electrolyte effects and have higher adhesive strengths compared to urethane and ester adhesives. Leveraging these characteristics, flexible pouch cells were manufactured and their stability was evaluated. The results confirm that the flexible cells demonstrate excellent stability, exhibiting potential for application in wearable devices.

Tuning Adhesion and Energy Dissipation in Polymer Films between Solid Surfaces via Grafting and Cross-Linking

Tuning Adhesion and Energy Dissipation in Polymer Films between Solid Surfaces via Grafting and Cross-Linking

Chemosensitive Properties of Electrochemically Synthesized Poly-3-Thienylboronic Acid: Conductometric Detection of Glucose and Other Diol-Containing Compounds under Electrical Affinity Control

Due to the presence of the boronic acid moieties, poly-3-thienylboronic acid has an affinity for saccharides and other diol-containing compounds. Thin films of this novel chemosensitive polymer were synthesized electrochemically on the gold surface. The adhesion of the polymer was enhanced by the deposition of a monomolecular layer of thiophenol. The technology was used to fabricate conductometric sensors for glucose and other diol-containing compounds. Simultaneous two- and four-electrode conductivity measurements were performed. The chemical sensitivity to sorbitol, fructose, glucose, and ethylene glycol was studied at different pH and electrode potentials, and the corresponding binding constants were obtained. Depending on the electrode potential, the reciprocal values of the binding constants of glucose to poly-3-thienylboronic acid at neutral pH are in the range of 0.2 mM–1.0 mM. The affinity for glucose has been studied in buffer solutions and in solutions containing the major components of human blood. It was shown that the presence of human serum albumin increases the affinity of poly-3-thienylboronic acid for diol-containing compounds.

Unlocking the Potential of Liquid Plasma Polymer Films: Characterizing Aging Effects and Their Impact on the Wrinkling Phenomenon.

Here, we present the study of the intricate dynamics between the physicochemical properties of liquid propanethiol plasma polymer films (PPFs) and the formation of wrinkles in PPF/Al bilayers. The study investigates the effect of liquid PPF aging in the air before top Al layer deposition by magnetron sputtering on the wrinkling phenomenon for 4 days. Thanks to atomic force microscopy, the wrinkle dimensions were found to decrease by approximately 55% in amplitude and 66% in wavelength, correlated with an increase in the viscosity of the PPF over the aging duration (i.e., from less than 107 to 1010 Pa·s). This behavior is not linked to alterations in cross-linking degree as evidenced by time-of-flight secondary ion mass spectrometry experiments but rather to network densification driven by the inherent molecular chain mobility due to the viscous state of the PPF. X-ray photoelectron spectroscopy measurements emphasizing the absence of oxidation of the PPF over the aging duration support this, revealing a unique aging mechanism distinct from other plasma polymer families. Overall, this study offers valuable insights into the design and application of mechanically responsive PPFs involved in bilayer systems, paving the way for advancements in nanotechnology and related fields.

Influence of biodegradable polymer films on conformation of polydiacetylene–silver nanocomposites as colorimetric time–temperature indicators

Time–temperature indicators (TTIs) are used to monitor the quality of packaged products by providing a visual indication of product deterioration due to time and temperature during transportation, storage, and distribution. This study aimed to investigate the effect of biodegradable polymer films on the limits of the color change mechanism in polydiacetylene. TTIs were prepared using biodegradable polymer films based on carboxymethyl cellulose, polyvinyl alcohol (PVOH), chitosan, and carboxymethyl chitosan (CMCh) with thermochromic properties provided by silver nanoparticles–polydiacetylene (10 % w/w AgNP–PDA). Vesicle and core–shell structures of AgNP–PDA appeared in the chitosan- and PVOH-based films owing to the effects of functional groups in the base polymer. Total color difference measurements indicated that the AgNP–PDA-containing films exhibited color changes in response to storage at 35 ℃ for a total of 14 days. Specifically, the AgNP–PDA in the chitosan- and PVOH-based films produced noticeable color changes from blue to reddish-purple or reddish-brown, respectively, which was influenced by the core–shell structure of AgNP–PDA embedded in the base polymer. The developed films are very promising for applications as TTI devices for tracking fresh products, supported by the compatibility of activation energy (Ea) from 29 to 79 kJ/mol.

Unlocking the Potential of Liquid Plasma Polymer Films: Characterizing Aging Effects and Their Impact on the Wrinkling Phenomenon.

Here, we present the study of the intricate dynamics between the physicochemical properties of liquid propanethiol plasma polymer films (PPFs) and the formation of wrinkles in PPF/Al bilayers. The study investigates the effect of liquid PPF aging in the air before top Al layer deposition by magnetron sputtering on the wrinkling phenomenon for 4 days. Thanks to atomic force microscopy, the wrinkle dimensions were found to decrease by approximately 55% in amplitude and 66% in wavelength, correlated with an increase in the viscosity of the PPF over the aging duration (i.e., from less than 107 to 1010 Pa·s). This behavior is not linked to alterations in cross-linking degree as evidenced by time-of-flight secondary ion mass spectrometry experiments but rather to network densification driven by the inherent molecular chain mobility due to the viscous state of the PPF. X-ray photoelectron spectroscopy measurements emphasizing the absence of oxidation of the PPF over the aging duration support this, revealing a unique aging mechanism distinct from other plasma polymer families. Overall, this study offers valuable insights into the design and application of mechanically responsive PPFs involved in bilayer systems, paving the way for advancements in nanotechnology and related fields.

Deformation mechanism of conjugated polymer films during single and cyclic stretching

Reversibility and durability have become new bottlenecks for conjugated polymers to realize “stretchable” semiconducting devices. Therefore, the correlation between microstructure and mechanical properties requires explicit delineation. Herein, the deformation and fracture mechanisms of DPP-TVT (poly [2,5-bis(4-decyl tetradecyl) pyrrolo [3,4-c]pyrrole-1,4-(2H, 5H)-dione-(E)-1,2-di (2,2′-bithiophen-5-yl)ethene) films with various degree of lamellar order were investigated from microscopic view. In the medium ordered films, the lamellae and amorphous phase cooperate to form the fibrous network structure in respond to tensile deformation. When recovered, this fibrous network could deform and being compressed, providing an efficient stress transfer pathway to accommodate the residual strain. Therefore, the medium ordered films did not form cracks even under 100 cycles of 50 % strain. However, in near-amorphous films, the uniformly aligned chains in stretched films were difficult to reorient under compression, resulting in the formation of large wrinkles and poor fatigue resistance. And the highly ordered films generate cracks both under single and cyclic stretch due to lacking of stress dissipation pathways. This study lays the groundwork for enhancing the mechanical robustness of conjugated polymer films.

Antimicrobial Polymer Films with Grape Seed and Skin Extracts for Food Packaging

The development of antimicrobial food packaging is a very important and current goal, but it still difficult to implement in practice. Reducing microbial contamination and preserving food quality are very important tasks for food manufacturers as the use of antimicrobial packaging can preserve the health of consumers. On the other hand, the difficulty of degrading packaging materials, leading to environmental pollution, is also an important problem. These problems can be solved by using biodegradable biopolymers and antimicrobial agents in the production of food packaging. Very suitable antimicrobial agents are grape seed and skin extracts as they have high antioxidant and antimicrobial capacity and are obtained from grape pomace, a waste product of winemaking. The present review presents the valuable bioactive compounds contained in grape seeds and skins, the methods used to obtain the extracts, and their antimicrobial and antioxidant properties. Then, the application of grape seed and skin extracts for the production of antimicrobial packaging is reviewed. Emphasis is placed on antimicrobial packaging based on various biopolymers. Special attention is also paid to the application of the extract of grape skins to obtain intelligent indicator packages for the continuous monitoring of the freshness and quality of foods. The focus is mainly placed on the antimicrobial properties of the packaging against different types of microorganisms and their applications for food packaging. The presented data prove the good potential of grape seed and skin extracts to be used as active agents in the preparation of antimicrobial food packaging.

Electrostatic Surface Charging by Water Dewetting.

Water dewetting generates static electricity. We reviewed historical experiments of this phenomenon, and we studied the charging of polymer slides and metal electrode supported polymer films withdrawn vertically from a pool of aqueous solutions. For pure water, charging was negative and surface charge densities increased with the speed of dewetting, which we explain by the thermally activated entrainment of nanometer-sized water droplets or clusters charged by unbalanced adsorbed electric double-layer ions. Surface charge densities increased for reduced polymer film thickness following a power law, which we explain by reduced discharge of the entrained water volumes. At low salinity c ≲ 10 μM, charging was proportional to electrokinetic interfacial charge densities: the negative charging was increased for alkaline solutions and for most salts at μM concentrations and the charge polarity was inversed to positive for a cationic surfactant, a salt with a highly positively charged cation, and for a strong acid at approximately pH 4. Charging was reduced again for c ≳ 100 μM, especially at high dewetting speeds and for chaotropic ions, which we explain by the entrainment of larger and more discharged droplets. We determined adsorption energies of the charged water clusters on the dewetted surface from thermally stimulated discharge of the charged polymer slides and we show that the surface charge distribution, imaged by charged toner powders and measured microscopically by Kelvin probe force microscopy, is a record of the dewetting process that provides spatial and kinetic information about the three-phase contact line motion.

Electrochemical polymer synthesis using thiophene and pyrrole/carbazole: Their electrochemical behaviours and capacitor performance

In this study, carbazole-derived monomers were synthesized on ITO-coated PET via electrochemical reactions and conductivity measurements of the resulting polymeric films were performed by UV, FT-IR, NMR, TG-DTG, SEM and AFM analyses. Their spectroelectrochemical properties were investigated. The carbazole (C) based thiophene (Th) polymer abbreviated as pThC and its copolymer with pyrrole (Py), named as pThC-Py were obtained by electrochemical polymerization method. The surface stability of the resulting polymer films was good depending on time. The contact angle (CA) between the water and theco- polymer surface was determined by dropping 6.09 μL of pure water and CA average was calculated as 68.19° < 90°. According to the thermal analysis data of the polymers, the thermal stability of the pThC-Py was better than pThC as it had higher thermal decomposition temperature. Comparisons of electrical conductivity measurements of the polymer films were made depending on the temperature (25, 50 and 90 °C). Due to increasing temperature, the electrical conductivity of pThC-Py film was read as 29.3 S/cm at 90 °C, and also the electrical conductivity values of the pThC-Py were determined as 1.92 × 10−2 S/cm at 25 °C and 14.2 S/cm at 50 °C. Because of the high electrical conductivity of the pThC-Py, its capacitor performance was tried to be determined from cyclic voltammetric measurements. According to the voltammetric results, the power density (P) and the energy density (E) values of the synthesized substance were calculated as 290.532 W/g and 9.684 Wh/g, respectively. This indicates that the amount of energy the material storable is relatively high. Moreover, it is possible to say that it can be included in the classical capacitor class and in the supercapacitor category by improving its features. Moreover, since the electrical conductivity of pThC-Py is quite good, it is thought that it may be suitable for use in electronic devices.

Preparation of chitosan/Tenebrio molitor larvae protein/curcumin active packaging film and its application in blueberry preservation

With growing concerns about postharvest spoilage of fruits, higher requirements have been placed on high-performance and sustainable active packaging materials. In this study, we prepared curcumin-based functional composite films using chitosan (CS) and Tenebrio molitor larvae protein (TMP) as the substrates. The effects of curcumin concentration on the structural and physicochemical properties of the composite films were determined. Curcumin was equally distributed in the polymer film through physical interactions. Furthermore, the curcumin composite film with 0.3 % addition exhibited a 27.39 % increase in elongation at break (EBA), a 37.04 % increase in the water vapor barrier, and strong UV-blocking properties and antioxidant activity compared with the control film (CS/TMP). The degradation experiment of the composite film on natural soil revealed that the composite film exhibited good biodegradability and environmental protection. Furthermore, the applicability of functional composite films for preserving blueberries was investigated. Compared with the control film and polyethylene (PE) films, the prepared composite films packaging treatment reduced the decay rate and weight loss rate of blueberries during storage, delayed softening and aging, and maintained the quality of blueberries. Using sustainable protein resources (TMP) and natural polysaccharides as packaging materials provides an economically, feasible and sustainable way to achieve the functional preservation of biomass materials.

Quantification of interfacial adhesion of multilayer polymeric films using a custom‐built instrumented machine

Quantification of interfacial adhesion of multilayer polymeric films using a custom‐built instrumented machine

Improvement of polycaprolactone and polyethylene glycol flexible polymeric film enhances bone volume and interconnectivity in bone lesions through transport of mesenchymal stem cells differentiated to osteoblasts

AbstractBone fractures are one of the most common types of human injury. This study aimed to create a synergistic action of polymeric films (PFs) based on polycaprolactone (PCL) and polyethylene glycol (PEG) (PCL‐PEG‐PFs) deposited by casting, combined with mesenchymal stem cells (MSCs) that differentiate into osteoblasts for bone regeneration. In vitro experiments indicated that the PCL‐PEG‐PFs (70:30) exhibited low cytotoxicity and enhanced cell adhesion capacity. In vivo studies were performed to evaluate the bone regeneration capacity of PFs with MSCs that adhered to and differentiated into osteoblasts. The cell differentiation process was carried out for 18 days in cell culture for subsequent implantation in the calvaria of male C57BL/6J mice, which remained in contact with the bone lesion for another 14 days. In vivo studies indicated that the application of PCL‐PEG‐PFs (70:30) increased the bone surface area to the total volume, with significant regeneration areas (levels greater than 25%) and interconnectivity compared to the control. In addition, the generated tissue presented cells with a morphology comparable to that of the peripheral tissue of the injured region, indicating a positive synergistic interaction between PCL‐PEG‐PFs (70:30) and MSCs differentiated into osteoblasts in contact with the bone lesion.

Facile route for processing natural polymers for the formulation of new low-cost hydrophobic protective hybrid coatings for carbon steel in petroleum industry

AbstractThis research helps with the creation, assessment, and characterization of a new hybrid protective coating for carbon steel alloy in acid conditions. The findings of this study will be useful for both chemical and petrochemical companies as well as scientists. This study aims to protect C-steel in acid pickling solution 1.0M HCl and formulate new hydrophobic protective hybrid organic–inorganic coatings from biopolymers chitosan and plant resin guar gum. Eight coating samples of chitosan in the absence and the presence of guar gum, silica and two heterocyclic compounds are prepared at feasible operational conditions using hot melt method. The aiding additives improved compatibility between coating constituents as confirmed by using different methods of analysis. This new processing approach has addressed the problems of using chitosan in corrosion control such as solubility in acid media and low mechanical strength. Coating samples of chitosan and its composites with the heterocyclic compounds (2-Hydrazinyl-6-methyl-4, 5-dihydro pyrimidine-4-on) or (2-Hydrazinyl-6-phenyl-4, 5-dihydro pyrimidine-4-on) are potent biocides. Coating shifts corrosion potential of carbon steel by 30 mV to more noble direction relative to the active potential 520 mV of bare carbon steel surface. Impedance and polarization measurements indicate that coating samples protect metal surface as mixed-type inhibitor by adsorption mechanism. There is a good agreement between percentages protection %P of coating calculated using the values of charge transfer resistance, Rct, and corrosion current density, icorr. All %P values are above 99% for all coating samples. Guar gum plant resin increases gloss of the coating film. Silica fills the pores in the polymeric film and increases the stuffiness of the polymeric coating film by modifying the particle size. All coated samples have high contact angle ranging from 150° to 165° indicating low wettability and high hydrophobicity of coating film on the metal surface.

Valorization of Seafood Waste for Food Packaging Development

Packaging plays a crucial role in protecting food by providing excellent mechanical properties as well as effectively blocking water vapor, oxygen, oil, and other contaminants. The low degradation of widely used petroleum-based plastics leads to environmental pollution and poses health risks. This has drawn interest in renewable biopolymers as sustainable alternatives. The seafood industry generates significant waste that is rich in bioactive substances like chitin, chitosan, gelatins, and alginate, which can replace synthetic polymers in food packaging. Although biopolymers offer biodegradability, biocompatibility, and non-toxicity, their films often lack mechanical and barrier properties compared with synthetic polymer films. This comprehensive review discusses the chemical structure, characteristics, and extraction methods of biopolymers derived from seafood waste and their usage in the packaging area as reinforcement or base materials to guide researchers toward successful plastics replacement and commercialization. Our review highlights recent advancements in improving the thermal durability, mechanical strength, and barrier properties of seafood waste-derived packaging, explores the mechanisms behind these improvements, and briefly mentions the antimicrobial activities and mechanisms gained from these biopolymers. In addition, the remaining challenges and future directions for using seafood waste-derived biopolymers for packaging are discussed. This review aims to guide ongoing efforts to develop seafood waste-derived biopolymer films that can ultimately replace traditional plastic packaging.

Development of Polymeric Films Based on Sunflower Seed Proteins and Locust Bean Gum

Most polymeric food packaging materials are non-biodegradable and derived from petroleum, thus recent studies have focused on evaluating alternative biodegradable materials from renewable sources, with polysaccharides and proteins as the main types of employed biopolymers. Therefore, this study aimed to develop biopolymeric films based on sunflower proteins and galactomannans from locust bean gum. The influence of the galactomannan amount (0.10%, 0.30%, 0.50%, and 0.75% w/v) on the physicochemical, thermal, and mechanical properties of cast sunflower protein-based films was studied. Sunflower proteins gave rise to yellowish, shining, and translucid films. With the incorporation of locust bean gum-derived galactomannans, the films became more brown and opaque, although they still maintained some translucency. Galactomannans significantly changed the proteins’ secondary structures, giving rise to films with increased tensile resistance and stretchability. Nevertheless, the increase in the galactomannan amount did not have a significant effect on the film’s thermal stability. The protein/galactomannan-based films showed values of water vapor and oxygen permeability that were slightly higher than those of the pristine materials. Overall, blending locust bean gum galactomannans with sunflower proteins was revealed to be a promising strategy to develop naturally colored and translucid films with enhanced mechanical resistance while maintaining flexibility, fitting the desired properties for biodegradable food packaging materials.

Bio-Based Polyurethane Networks Containing Sunflower Oil Based Polyols

This work focused on the preparation and investigation of polyurethane (SO-PU)-containing sunflower oil glycerides. By transesterification of sunflower oil with glycerol, we synthesized a glyceride mixture with an equilibrium composition, which was used as a new diol component in polyurethanes in addition to poly(ε-caprolactone)diol (PCLD2000). The structure of the glyceride mixture was characterized by physicochemical methods, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), nuclear magnetic resonance spectroscopy (NMR), and size exclusion chromatography (SEC) measurements. The synthesis of polyurethanes was performed in two steps: first the prepolymer with the isocyanate end was synthesized, followed by crosslinking with an additional amount of diisocyanate. For the synthesis of the prepolymer, 4,4’-methylene diphenyl diisocyanate (MDI) or 1,6-hexamethylene diisocyanate (HDI) were used as isocyanate components, while the crosslinking was carried out using an additional amount of MDI or HDI. The obtained SO-PU flexible polymer films were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The so-obtained flexible SO-PU films were proved to be suitable for the preparation of potentially biocompatible and/or biodegradable scaffolds. In addition, the stress versus strain curves for the SO-PU polymers were interpreted in terms of a mechanical model, taking into account the yield and the strain hardening.

Dynamic Recyclable High-Performance Epoxy Resins via Triazolinedione–Indole Click Reaction and Cation–π Interaction Synergistic Crosslinking

Thermosetting plastics exhibit remarkable mechanical properties and high corrosion resistance, yet the permanent covalent crosslinked network renders these materials challenging for reshaping and recycling. In this study, a high-performance polymer film (EI25-TAD5-Mg) was synthesized by combining click chemistry and cation–π interactions. The internal network of the material was selectively constructed through flexible triazolinedione (TAD) and indole via a click reaction. Cation–π interactions were established between Mg2+ and electron-rich indole units, leading to network contraction and reinforcement. Dynamic non-covalent interactions improved the covalent crosslinked network, and the reversible dissociation of cation–π interactions during loading provided effective energy dissipation. Finally, the epoxy resin exhibited excellent mechanical properties (tensile strength of 91.2 MPa) and latent dynamic behavior. Additionally, the thermal reversibility of the C-N click reaction and dynamic cation–π interaction endowed the material with processability and recyclability. This strategy holds potential value in the field of modifying covalent thermosetting materials.

Modelling of energy harvesting with bendable concrete and surface-mounted PVDF

Polyvinyl alcohol fiber reinforced engineered cementitious composite (ECC) using piezoelectric polymer film has attracted significant interest due to its energy harvesting potential. This work provides a theoretical model for evaluating the energy harvesting of bendable ECC using surface-mounted polyvinylidene fluoride (PVDF). In the mechanical part, concrete damage plasticity model based on the explicit dynamic analysis was utilized to simulate the dynamic flexural behavior of ECC beam under different dynamic loading rates. The mechanism of force transfer through the bond layer between the PVDF film and ECC specimen was simulated by a surface-surface sliding friction model wherein the PVDF film was simplified as shell element to reduce computational cost. Then, the electromechanical behavior of the piezoelectric film was simulated by a piezoelectric finite element model. A simplified model was also given for a quick calculation. The theoretical model was verified with the experimentally measured mechanical and electrical results from the literature. Finally, a parametric analysis of the effects of electromechanical parameters on the efficiency of energy harvesting was performed. The verified theoretical model can provide a useful tool for design and optimization of cementitious composite systems for energy harvesting application.