Polymer Films Research Articles

Effects of Storage Temperatures and Times on Drying Chicken Breasts Using Film‐Drying: A New Application of Polymeric Film for Food Preservation

ABSTRACTThis present study reports the effect of different storage temperatures on the film‐dried chicken breast (FDCB) by film‐drying technique for 15 days, including FDCB‐(−18), FDCB‐4, FDCB‐18, FDCB‐28 and FDCB‐38 (°C). Both storage time and temperature negatively affected the water‐holding capacity and moisture ratio, except for FDCB‐(−18). To ensure the quality of film‐dried chicken meats, they were rehydrated and evaluated in terms of colour values, tissue microstructure and hardness. The results showed that the rehydrated samples FDCB‐28 and FDCB‐38 promoted redness loss and increased the hardness values compared with other samples at low temperatures. Moreover, the storage temperature below 28°C was the most effective strategy for best maintaining the physicochemical, antioxidative, microbiological and sensory quality of film‐dried chicken samples, similar to those of raw meat. Interestingly, the FDCB‐(−18), FDCB‐4 and FDCB‐18 samples showed a significant (p < 0.05) inhibitory effect on microbial growth and lipid oxidation for 15 days.

Electropolymerization and characterization of a new ambipolar perimidine polymer with a perylene core

We successfully synthesized a stable electroactive perinone polymer by electropolymerization from the mixture of syn- and anti- isomers (ratio 1:1) of 3,4:9,10-bis(1,8-naphthapyrimidine)-1,6,7,12-tetrakis(1,1,3,3-tetramethylobutylphenoxy)perylene (NPP). The polymer p(NPP) exhibited distinct redox process, with reduction at -1.20 V and oxidation at 0.60 V (vs. ferrocene/ferrocenium couple). Spectroscopic and computational analyses confirmed structural similarity of the polymer to its monomeric form, revealing a perimidine unit involved in electrocoupling. Our thorough investigations elucidated the redox reactions electrochemical mechanism within the polymer film, identifying predominantly deprotonated bis-perimidine segments contributing to oxidation peaks at 0.60 V and 0.68 V. Additionally, the perylenediamide core exhibits the reversible, multi-stage reduction process. Impedance analysis highlighted efficient n-doping-induced conductivity, suggesting application in organic optoelectronic devices. This work positions p(NPP) as a versatile ambipolar multiredox p- and n-type conductor, indicating a potential for expanding perinone-based perylene-diperimidine polymers for innovative electronics.

Ferroelectric Thin Films and Composites Based on Polyvinylidene Fluoride and Graphene Layers: Molecular Dynamics Study

This work is devoted to the study of nanosized polymer polyvinylidene fluoride (PVDF) thin ferroelectric films (two-dimensional ferroelectrics) and their composites with graphene layers, using molecular dynamics methods to (1) study and calculate the polarization switching time depending on the electric field and film thickness, (2) study and calculate the polarization switching time depending on changes of the PVDF in PVDF-TrFE film, and (3) study the polarization switching time in PVDF under the influence of graphene layers. All calculations at each MD run step were carried out using the semi-empirical quantum method PM3. A comparison and analysis of the results of these calculations and the kinetics of polarization switching within the framework of the Landau–Ginzburg–Devonshire theory for homogeneous switching in ferroelectric polymer films is carried out. The study of the composite heterostructures of the “graphene-PVDF” type, and calculations of their polarization switching times, are presented. It is shown that replacing PVDF with PVDF-TrFE significantly changes the polarization switching times in these thin polymer films, and that introducing various graphene layers into the PVDF layered structure leads to both an increase and a decrease in the polarization switching time. It is shown that everything here depends on the position and displacement of the coercive field depending on the damping parameters of the system. These phenomena are very important for various ferroelectric coatings.

Rational Design of a Portable Chemometric-Assisted Voltammetric Sensor Based on Ion-Imprinted Polymeric Film for Co(II) Determination in Water.

Herein, chemometric-assisted synthesis of electrochemical sensors based on electropolymerised ion-imprinted polymeric (e-IIP) films was explored. Co(II)-IIPs sensors were prepared by performing electropolymerisation procedures of polymerisation mixtures comprising varying concentrations of an electroactive o-aminophenol (o-AP) monomer and Co(II) ions, respectively, according to the Taguchi L9 experimental design, exploiting the simultaneous evaluation of other controlled parameters during electrosynthesis. Each e-IIP developed from Taguchi runs was compared with the respective non-imprinted polymer (NIP) films and fitted according to Langmuir-Freudlich isotherms. Distinctive patterns of low and high-affinity films were screened based on the qualities and properties of the developed IIPs in terms of binding kinetics (KD), imprinting factor, and the heterogeneity index of produced cavities. These results can provide a generic protocol for chemometric-assisted synthesis of e-IIPs based on poly-o-AP, providing highly stable, reproducible, and high-affinity imprinted polymeric films for monitoring purposes.

Triple passivation strategy for ultra-stable luminous CsPbBr3 NCs-Acrylate based films as backlight display

To improve the stability of CsPbBr3 nanocrystals (NCs), triple protection strategies were performed to obtain the ultra-stable films, including fluorinated hydrophobic film surface, polymer coating and silica encapsulation. CsPbBr3 QDs@SiO2 nanoparticles (SiPNCs) were prepared with well-dispersed NCs (8 nm) within acrylate-modified silica-shell. Polymer@SiPNCs (poly@SiPNCs) films were prepared by copolymerization of methyl methacrylate (MMA), 2,2,3,3,4,4,5,5,6,6,7,7-dodecafluoroheptyl methacrylate (DFHM) and SiPNCs under ultraviolet (UV) light. Compared to CsPbBr3 NCs solution, SiPNCs solution had well maintained light absorption and emission wavelengths of ∼509 nm and ∼522 nm respectively. High SiPNCs content resulted in enhanced micro/nano structure and increased roughness on the surface of poly@SiPNCs film. With increasing SiPNCs content, water contact angles (WCAs) of poly@SiPNCs films reached 126 ± 2.4°, 137.3 ± 1.3° and 141.5 ± 1.9° respectively. This fabricated poly@SiPNCs film exhibited much improved stabilities to water and UV light, even after 90 days of water immersion and 120 h of UV irradiation. White light-emitting-diode (LED) device emitted bright pure white light. This work will boost a large-scale preparation of stable QDs films as backlight display.

Organic room-temperature phosphorescence of imidazole-based films by self-assembly enhancement strategies

Organic room-temperature phosphorescence (RTP) shows high potential in optical fields, and self-assembly method via various non-covalent interactions is one facile and efficient way to enhance RTP performance. Herein, we investigated the RTP behaviors of three imidazole-based polymer films containing imidazole, methyl imidazolium, and benzyl imidazolium moieties, respectively. Their RTP behaviors and chemical structures were compared and discussed to explore the underlying structure-properties relationships. Owing to plenty of hydrogen bonds of polyacrylamide matrix to lock phosphors, imidazolium-based films gave an obvious green RTP due to cations and iodine anions-enhanced intersystem crossing. The blue RTP signals of imidazole-containing film was aroused by coordination with Zn2+ ions due to crosslinking and heavy atom effects. Moreover, the RTP performance of benzyl imidazolium-based film was remarkably improved by host-guest complexation with cucurbit[7]uril, showing a long lifetime up to 230.6 ms. By utilizing the difference in their RTP lifetimes, information encryption application was successfully achieved as a proof of concept.

Designing a New Class of Mechanophoric Polymer Based on Epoxy-Functionalized Rhodamine Derivative.

Mechanophoric polymers are an interesting class of smart polymers which contains a special force-sensitive molecular motif that can lead to a chemical change within the polymer network in response to mechanical force. This investigation reports the design of a mechanophoric polymer based on epoxy-functionalized rhodamine via a monomeric approach. In this case, rhodamine (Rh) is modified with glycidyl methacrylate (GMA) through an epoxy-amine reaction to design a vinyl-functionalized multi-armed macromonomer (Rh-GMA), which is reacted with butyl acrylate (BA) to prepare the crosslinked polymeric film. The crosslinked polymeric film demonstrates mechanophoric properties under UV and stretching conditions.

Spray-deposition of graphene/polymer thin coatings on polyimide sheets for lunar dust adhesion mitigation

NASA seeks to develop technologies to mitigate dust accumulation from planetary surfaces on robotic and human systems hardware during planned space exploration missions. With a return to the Lunar surface, lunar dust threatens the durability and reusability of components and vehicles due to its fine, jagged morphology and highly abrasive nature. Lunar dust consists of particles less than 60 μm in size that are chemically reactive, electrostatically and sometimes magnetically charged. Unique materials and technologies that reduce or mitigate lunar dust adhesion will be critical to support long duration missions and eventual sustained presence on the lunar surface. The goal of this work was to prepare dust resistant, space durable polymer films to satisfy dust accumulation mitigation needs for future NASA missions. In this regard, several graphene coated polyimide thin films have been developed with surface resistivity properties in the range of 103 Ω/sq to 1011 Ω/sq and evaluated for their dust adhesion performance. Raman spectroscopy was used to characterize and assess the quality of graphene ink coated sheets while surface resistivity measurements were used to assess electrical conductivity. Scratch testing and abrasion resistance measurements were used to evaluate overall abrasion performance. Water contact angle and optical microscopy were used to evaluate changes in surface topography and chemistry. Graphene coated polyimide surfaces with charge dissipative resistivity (106 Ω/sq) demonstrated a minimum in residual particle areal coverage compared to conductive and insulating surfaces.

Study of the properties of combined multilayer polymer materials for aeronautical equipment

The results of studies of changes in the physical and mechanical properties of heat-resistant polyethylene terephthalate (PET), polymide (PI) and fluoroplastic (PP) films, as well as synthetic polyethylene terephthalate (PET) and aramid fabrics in a wide range of specified exposure temperatures and temperature exposure times are presented. The most suitable heat-resistant polymer films and fabrics for use in inflatable structures of aeronautical equipment have been identified. An assessment of the operational parameters of the investigated materials showed linear character of change in properties in a given temperature and time interval of researches.

Characterizing the thickness and temperature dependence of elastic modulus in polymer films using picosecond ultrasonics

Abstract Polymer nanofilms have found extensive applications in fields such as medical science and microelectronics, making the exploration of their mechanical properties highly significant. In this study, we examine the dependency of the out-of-plane elastic modulus of polymer films on both thickness and temperature, utilizing picosecond ultrasonics. Multiple acoustic modes of a polymer film are employed to measure its elastic modulus with heightened precision. Measurements are conducted on samples with different thicknesses and at different temperatures. The results indicate that the modulus of polymer nanofilms strongly depends on both thickness and temperature. For polymethyl methacrylate (PMMA) films with a thickness of less than 81 nm, the modulus determined exhibits a decrement correlating with thickness and is quantifiably inferior to the analogous bulk value. Additionally, as the temperature rises, the elastic modulus declines at clearly varying rates, which are described by two distinct modulus-temperature coefficients.

Effect of different nanofillers incorporation on HDPE/LDPE films nanocomposite

The objective of this study was to develop polymeric films of high-density polyethylene (HDPE)/low-density polyethylene (LDPE) that comprise 1 wt% of different nanofillers, that is, either nanofibrillated cellulose (NFC), montmorillonite clay (MMT), or graphene nanoplatelets (GNPs); the polymeric films were developed with and without the inclusion of a coupling agent (CA). The results indicated that all the samples that comprised nanofillers exhibited, at least, an increase of 3 to 25°C compared with that of the matrix and demonstrated higher stability at the beginning of the thermal degradation, as verified using TGA. In the DSC analysis of the samples that contained GNPs had highest crystallinity index (55%), having as the consequent improvement in the mechanical properties and in the oxygen permeation. The incorporation of GNPs provided a 127.71% increase in deformation at break and a lower value in oxygen permeability with 50.06 mL.cm.(cm2.s.cmHg)−1, when compared to the polymeric matrix. It was concluded that all the different nanofillers tested promoted distinct improvements in HDPE/LDPE films nanocomposite. It can be inferred that these modifications are related to the chemical composition, size and morphology of each nanofiller. Thereby, it is indicated that with the use of each nanofiller one must be in accordance with the necessary demand of each composite film.

Direct Growth of a Polymer Film to Induce Horizontal Orientation of Zn4(OH)6SO4·xH2O for Stable Zn Metal Batteries.

The loose and randomly oriented byproduct (i.e., Zn4(OH)6SO4·xH2O, ZHS) in situ formed on the zinc (Zn) surface is recognized to be the primary cause for dendritic Zn growth and side reactions. Switching the detrimental passivation film into a dense and kinetically favorable solid electrolyte interphase (SEI) is a straightforward strategy to tackle these issues faced by Zn metal anodes but remains largely unexplored. Herein, a new polymer film directly grown on Zn metal through room-temperature plasma-enhanced chemical vapor deposition is proposed to induce the lateral growth of ZHS nanosheets and decrease the Zn2+ desolvation barrier, thereby forming a beneficial composite SEI for suppressing Zn dendrite growth and surface corrosion. As a result of the joint effect, we realize an impressively stable cycling behavior in symmetric cell over 3400 h at 2 mA cm-2. Moreover, full cells also demonstrate prolonged lifespans. This work opens a new avenue for stabilizing Zn metal batteries by turning detrimental ZHS into a favorable interlayer.

Preparation of stable polyvinyl alcohol/polyurea hydrogel using oligomeric compounds containing urea-bonded

The aim of this research is the production of a biocompatible hydrogel film with high stability; the polymer should absorb enough water, and its structure should be preserved in water for a long time and not disintegrate. Polyvinyl alcohol (PVA) was chosen as the main polymeric base of the desired hydrogel. Oligomeric compounds with urea bonded containing active groups at two chain ends can react with the hydroxyl groups of the polymer and play the role of a cross-linker. Urea linkage oligomers (ULO) were prepared by reacting 2 mol of sulfamic acid, 3 mol of phosphorus, and 8 mol of urea in a molten state. The amount of PVA was kept constant, while the amount of ULO was different, the prepolymer solution was mold-dried at ambient temperature and subjected to a heat press. The gel behavior and characterization of the polymer films were investigated by FT-IR, NMR, SEM, ion chromatography, and XRD analyses, the data on the tensile strength and antibacterial properties of the samples are also reported. The production of a hybrid composite consisting of PVA and polyurea under the heat press has been confirmed; the ammonium phosphate, sulfate, nitrate, and melamine powder were produced in the layer of polymer structure. This innovative hybrid polymer with a network of urea bonds can be a favorable option for skin treatment applications due to the specific characteristic of urea known as keratolytic.

Preparation ofhydrogels based on natural polymers for pelleting of sugar beet seeds

One of humanity`s important problems is the lack of water in arid regions. One of the ways to solve the water shortage problem is the use of seed pelleting technology. The polymer film coating contributes to the effective maintenance of their quality during storage, including humidity regulation. The creation of effective coatings based on biodegradable natural polymers will help preserve natural resources and prevent environmental pollution. The purpose of this work is the radiation synthesis and characterization of hydrogels based on natural and synthetic polymers and the search for optimal conditions for coating the seeds with the resulting polymers. The methodology of the work includes the radiation synthesis of hydrogels, physicochemical characterization by gravimetry, germination, and germination energy study of coated seeds. Results and discussion. Hydrogels based on chitosan, polyvinylpyrrolidone, starch, and agar-agar were obtained using the radiation. The optimal parameters are 25 kGy irradiation dose and 5wt.% starch concentration. The presence of agar-agar in the hydrogel composition and the increase of irradiation dose from 15 to 45 kGy boost the gel fraction yield. The work investigated the water-holding capacity of pelleted seeds and the process of water desorption from the polymer shell. It has been established that the polymer shell around the seed can retain water in the early stages of its development. Seeds coated in two layers retain moisture 7 times longer compared to uncoated samples. Conclusion. These results can be used to manage seed performance potential and subsequent yield, including improving seed quality and nutrient delivery.

Study of poly allyl diglycol carbonate Kinetics treatment induced by ultrasonic frequency plasma

This research reveals the possibility of altering the structural, surface, fluorescence, and optical characteristics of CR-39 polymer detector by the effect of Ultrasonic frequency (UF) plasma argon gas. The samples were exposed to the plasma at different times ranging from 20 min to 100 min. Fourier Transform Infrared (FTIR) Spectroscopy, contact angle goniometer, surface roughness tester, photoluminescence spectroscopy, and UV/Vis Spectroscopy have been applied to analyze alterations of CR-39 polymeric films to understand the mechanisms of produced alterations by plasma treatment. The obtained FTIR spectra demonstrated that the plasma treatment-related changes in the absorption bands are associated with the treatment time, leading to two critical processes, degradation, and crosslinking. In comparison to the untreated surface, the surface wettability results showed that the liquids' contact angle decreased after treatment with a UF plasma source. This modification in the treated surface denotes an increase in polar groups there, which causes the surface to change to a hydrophilic state. The surface roughness of the samples following plasma treatment showed that UF plasma significantly changed the surface morphology of the CR-39 films. After plasma exposure, considerable emission bands were produced, and the photoemission spectra of the treated film showed a fluorescence response. As the exposure time increased, more fluorescence peaks were formed due to the increase in defects. The UV/Vis spectra showed that the modified films' absorption edges were moved toward lower photon energies. This resulted in a smaller optical energy gap, which led to an expansion of the carbon cluster. Additionally, the untreated sample's transmittance dropped from 92% to 47% for the treated film. In contrast to untreated films, a change in optical characteristics was seen in treated films.

Compact Mid‐Infrared Spectrometer Using Continuously Variable Infrared Filter and Microbolometer Array for Simple and Fast Measurement of Molecular Mid‐IR Spectra

AbstractThe mid‐infrared (mid‐IR) region is attractive for spectroscopy because this range has molecular fingerprint information. Existing FTIR‐based systems are limited by their complex optical systems, highlighting the ongoing necessity to advance miniaturization and simplify these systems. Here, a compact mid‐IR spectroscopy is introduced in the mid‐IR range, utilizing a continuously variable mid‐IR filter. This filter is made from Germanium (Ge) and BaF2 and is produced using physical vapor deposition. Continuously varying wavelengths of mid‐IR light are transmitted from different areas of the filter. These different wavelengths of light enter each pixel of the microbolometer array. Calibration is conducted using a sample material to match each pixel of the microbolometer array to its corresponding wavelength. Additionally, a deconvolution algorithm is applied to sharpen the acquired spectrum. This results in acquisition of high signal‐to‐noise ratio mid‐IR spectra in the LWIR region. Using this technology, mid‐IR spectroscopy for several types of samples like polymer film, and gas molecules is possible. In addition, by adopting total internal reflection, it is possible to measure non‐uniform thickness samples, such as liquid droplets.

Transient Interfacial Pattern Formation in Block Copolymer Thin Films via Sequential Thermal and Solvent Immersion Annealing.

A variety of structures encountered in nature only arise in materials under highly nonequilibrium conditions, suggesting to us that the scope for creating new functional block copolymer (BCP) structures might be significantly enlarged by embracing complex processing histories that allow for the fabrication of structures quite unlike those created under "near-equilibrium" conditions. The present work examines the creation of polymer film structures in which highly nonequilibrium processing conditions allow for the creation of entirely new types of transient BCP morphologies achieved by transitioning between different ordered states. Most previous studies of BCP materials have emphasized ordering them from their disordered state obtained from a solution film casting process, followed by a slow thermal annealing (TA) process at elevated temperatures normally well above room temperature. We have previously shown that achieving the equilibrium TA state can be accelerated by a direct solvent immersion annealing (DIA) preordering step that creates nascent ordered microstructures, followed by TA. In the present work, we examine the reverse nonequilibrium sequential processing in which we first thermally anneal the BCP film to different levels of partial (lamellar) order and then subject it to DIA to swell the lamellae. This sequential processing rapidly leads to a swelling-induced wrinkle pattern that initially grows with immersion time and can be quenched by solvent evaporation into its corresponding glassy state morphology. The article demonstrates the formation of wrinkling "defect" patterns in entangled BCP films by this sequential annealing that does not form under ordinary TA conditions. At long DIA times, these highly "defective" film structures evolve in favor of the equilibrium morphology of parallel lamellae observed with DIA alone. In conjunction with our previous study of sequential DIA + TA, the present TA + DIA study demonstrates that switching the order of these processing methods for block copolymer films gives the same final state morphology in the limit of long time as any one method alone, but with drastically different intermediate transient state morphologies. These transient morphologies could have many applications.

Bending creep behaviour of various polymer films analysed by surface strain measurement.

Understanding the temporal bending deformation of polymer films is key to designing mechanically durable flexible electronic devices. However, such creep behaviour under persistent bending remains unclear due to a lack of precise and accurate bending strain analysis methods. Herein, we quantitatively analysed the bending creep behaviour of various polymeric films using our developed strain measurement method that can precisely measure surface strain from optical diffraction. The surface strain measurement reveals that bending creep deformation differs depending on the polymer structure. The four-element Burgers model was employed to model the temporal strain increase on the bending surface successfully. By fitting the four-element model to the time course of the measured surface strain, we found that each polymer film has a different threshold surface strain for the appearance of bending creep deformation. Such disparity in the bending creep behaviour can be explained by the difference in strain energy density between the polymer films and their elastic model; polymer films with a small strain energy density difference show small bending creep deformation. The results obtained in this study contribute to the elucidation of the bending creep behaviour of polymer films and the development of flexible electronic devices operated under persistent bending.

A finite element framework on water vapor transmission rates by pinhole damages in inorganic ultrabarriers for flexible electronics

This work presents a computational framework to predict possible scenarios of pinhole distributions in hermetic barrier encapsulated organic layers to fill the lack of pinhole damage studies in thin film/organic electronics to a great extent. We describe various scenarios, including multiple pinhole damages of varying sizes and distances on a polymer film. An equation of water vapor transmission rates is proposed for polyimide films encapsulated with ALD ultrabarriers from computational experiments performed with different strategies. The validity of this equation covers pinhole damages ranging from 100 nm to 2.2 mm and any size of surface area of the film can be applied. Since the proposed equation does not include the interaction of wetness gradients with neighboring pinholes, the distance effect is investigated to estimate decreases in WVTR as the distance decreases between pinholes. An interactive, customized graphical user interface was created with ANSYS Parametric Design Language to make computational calculations user-friendly and widely available to researchers. Solution strategies of complete and unit cell runs, including standard and sub-modeling approaches, are proposed with advantages and disadvantages in computational time and accuracy of results.

Boundary Frustration in Double-Gyroid Thin Films.

Self-consistent field theory for thin films of AB diblock polymers in the double-gyroid phase reveals that in the absence of preferential wetting of monomer species at the film boundaries, films with the (211) plane oriented parallel to the boundaries are more stable than other orientations, consistent with experimental results. This preferred orientation is explained in the context of boundary frustration. Specifically, the angle of intersection between the A/B interface and the film boundary, the wetting angle, is thermodynamically restricted to a narrow range of values. Most termination planes in the double gyroid cannot accommodate this narrow range of wetting angles without significant local distortion relative to the bulk morphology; the (211)-oriented termination plane with the "double-wave" pattern produces relatively minimal distortion, making it the least frustrated boundary. The principle of boundary frustration provides a framework to understand the relative stability of termination planes for complex ordered block polymer phases confined between flat, nonpreferential boundaries.