Formation Of Polymer Films Research Articles

Scalable Photo-Responsive Physical Unclonable Functions via Particle Kinetics.

The increasing menace of counterfeiting and information theft underscores the urgent need for security platforms compatible with both micro- and nanoelectronics. Existing methods for anticounterfeiting labeling and cryptographic systems rely on unclonable patterns derived from the unpredictable variability of physical phenomena. However, these approaches impose limitations on the scalability of security components. Here we present a scalable platform for photoresponsive physically unclonable functions based on oxide particle kinetics in polymer solutions. The stochastic agglomeration process occurring during the formation of polymer films with dispersed oxide particles yields random patterns, with pixel sizes scalable from micro to nanoscales. We produce mechanically flexible and self-destructible optical unclonable function patterns utilizing oxide aggregates on a polymer film. Moreover, we establish a strategy for generating electrical unclonable patterns on a conducting polymer film. This involves covering the polymer film with an aggregate pattern mask, which serves as an ultraviolet-blocking layer for randomly exposing the film to ultraviolet ozone treatment. These unclonable patterns constitute robust and compact security systems, exhibiting effective resilience against machine-learning attacks (∼50% prediction error for training data sets of 1000). The developed scalable platforms for physically unclonable functions provide a hardware solution for robust cryptographic applications.

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.

Simulation aspects of patterning polymer films via evaporative lithography and composite substrates

The continuing development of evaporative lithography is important for many areas such as the creation of photonic crystals for optronics and microelectronics, the development of biosensors for medical applications and biotechnology, and for the formation of functional coatings for nanotechnology, including the application of thin, protective polymer coatings. The article proposes a mathematical model that allows us to explain the basic mechanisms of the formation of thin polymer films (less than 50 μm thick) during their deposition onto a composite substrate by methanol evaporation from a solution. If the thermal conductivity of the substrate is spatially non-uniform, this results in inhomogeneous evaporation along the free film surface. Therefore, as the film dries, a patterned polymer coating is left behind on the substrate. The mathematical model described here is based on the lubrication approximation and takes into account the dependence of the solution density on the concentration. The numerical computation results are in qualitative agreement with the experimental data of other authors. The article shows that solutal Marangoni flow plays a primary role in the process under consideration. This study allows us to better understand the mechanisms that can be used in evaporative lithography.

An ambipolar PEDOT-perfluorinated porphyrin electropolymer: application as an active material in energy storage systems.

The development of functional organic materials is crucial for the advancement of various fields, such as optoelectronics, energy storage, sensing, and biomedicine. In this context, we successfully prepared a stable ambipolar perfluoroporphyrin-based polymeric film by electrochemical synthesis. Our strategy involved the synthesis of a novel tetra-pentafluorophenyl porphyrin covalently linked to four 3,4-ethylenedioxythiophene (EDOT) moieties. The resulting monomer, EDOT-TPPF16, was obtained through a straightforward synthetic approach with a good overall yield. The unique molecular structure of EDOT-TPPF16 serves a dual function, with EDOT moieties allowing electropolymerization for polymeric film formation, while the electron-acceptor porphyrin core enables electrochemical reduction and electron transport. The electrochemical polymerization permits the polymer (PEDOT-TPPF16) synthesis and film formation in a reproducible and controllable manner in one step at room temperature. Spectroelectrochemical experiments confirmed that the porphyrin retained its optoelectronic properties within the polymeric matrix after the electrochemical polymerization. The obtained polymeric material exhibited stable redox capabilities. Current charge-discharge cycles and electrochemical impedance spectroscopy of the electrochemically generated organic film demonstrated that the polymer could be applied as a promising active material in the development of supercapacitor energy storage devices.

Microstructural and polymer film interaction mechanisms: Insights of GO-reinforced polymer-modified cement composites

The effects of graphene oxide (GO) on cement hydration phases and polymer film formation in GO-reinforced polymer-modified cement (GOPMC) composites were investigated by analysing interactions of film chemical structure and cement hydration kinetics towards enhanced engineering performance. Chemical characterisation by FTIR and XRD analyses revealed that alterations of the cement matrix's chemical structure, such as slow Ethylene vinyl acetate (EVA) hydrolysis, increased calcium-silicate-hydrate (C–S–H) and portlandite Ca(OH)2, were more pronounced in GOPMC composites, indicating direct and robust involvement of GO during early-age hydration kinetics. Isothermal calorimetry displayed an increased heat flow of ∼7.2 % for GOPMC compared with the reference PMC composite. Notably, air voids of GOPMC composite revealed polymer film sheets intermingled with cement hydration products to promote elastic interconnections and microstructural uniformity. Accordingly, the GOPMC composite displayed ∼16 % higher tensile strength at 28 days versus the PMC composite, primarily attributable to GO nucleation, due to its seeding effect on cement hydration kinetics thereby inducing marginally slower EVA hydrolysis, increased C–S–H nucleation sites, and smaller-sized CH crystals while mechanically reinforcing polymer films. More significantly, GO reinforced the microstructure of the GOPMC composites with no apparent chemical interference of crucial film-forming properties. This research provides a fundamental understanding of this novel material's characteristic properties and framework of engineering performance optimization for future infrastructure applications.

Application of polymer cement repair mortar in underground engineering: A review

Polymer-modified cementitious repair materials have gained attention as innovative and environmentally friendly construction materials due to their superior water retention, adhesion, freeze-thaw resistance, corrosion resistance, air permeability, and shrinkage resistance compared to ordinary repair materials. Adding a small amount of polymer can alter the concrete microstructure and form a composite material through the interaction between polymer film formation and cement hydration. This review shows that adding a certain percentage of polymers to concrete can improve the physical, fresh properties, durability, mechanical properties and microstructural development of concrete and improve the effectiveness of concrete repair treatment of underground structures. The discovery of different types and amounts of polymer cement from both physical and chemical perspectives can significantly enhance the performance of cement mortar. Various modifications, such as fibers and nanomaterials are explored to improve the properties of polymer cement for optimal treatment results. Finally, this paper summarizes key findings and provides recommendations for future research.

Tunable honeycomb-hierarchical multiscale structures of 2D/3D porous PLA/CCN composite films fabricated by the breath figure method

Highly ordered porous structures of PLA composite films can be designed with the addition of calcium carbonate nanoparticles (CCN) in polymeric film formation using the breath figure (BF) technique at controlled humidity. Both 2D and 3D monodispersed honeycomb-like porous structures of the PLA composite films are achieved by the adding CCN at the concentration of up to 1.00 phr, whereas hierarchically multiscale porous structures of the PLA/CCN films are obtained when the CCN concentration in the composites increases to more than 1.00 phr. These structures can be fabricated due to three mechanisms: water absorption and condensation, nano-Pickering emulsion, and capillary flow by self-assembly of the nanoparticles. Moreover, the nano effects of CCN on polymeric film fabrication are maximized by increasing the relative humidity to 90%, resulting in the formation of porous multilayers up to 95–120 μm in thickness. The application of the prepared porous composite films of PLA/CCN in the food and medical industries was illustrated. A model colorimetric sensor is made from PLA/CCN composite films enriched with bromothymol blue. The color of the films quickly changes from yellow to blue within 10 min after coming into contact with histamine, a representative gas generated from spoiled food.

Analysis of polycarbonate degradation at melt/FeCr-alloy interfaces as a function of the alloy composition by means of combinatorial thin film chemistry

Interfacial reactions at the polycarbonate (PC)/FeCr-alloy interface during melt contact were studied as function of the Fe:Cr ratio within the alloy. Thin Fe/Cr films with lateral composition gradients were deposited by magnetron sputtering; the analysis of the films was done with microscopy and X-ray photoelectron spectroscopy (XPS). The local interfacial polymeric film formation could be therefore directly correlated with the Fe:Cr ratio. The local thickness and structure of the formed polycarbonate residue was analyzed by means of imaging ellipsometry, atomic force microscopy as well as Fourier-transform infrared spectroscopy under grazing incidence and XPS. Moreover, confocal fluorescence microscopy of the PC melt/alloy interface could reveal the formation of minor degradation products in the interphase region. The results show that already an Fe:Cr ratio of 2 : 1 leads to a strong inhibition of the thermal degradation in comparison to the unalloyed iron, and that in general, the enrichment of chromium in the passive film leads to an effective suppression of interfacial PC degradation. The data contributes to improving the mechanistic understanding of the role of iron during this process. Additionally, a critical concentration of chromium in the alloys used for PC processing can be deduced.

Thin Cationic Polymer Coatings against Foodborne Infections

Biocidal coatings are known to minimize or terminate development of bacterial and fungicidal infections. In this paper, biocidal activity of seven cationic (co)polymers with amino groups—polyethyleneimine, polyallylamine, polydiallyldimethylammonium chloride/polyhexamethylene guanidine copolymer, diallyldimethylammonium chloride/SO2 copolymer, linear and hyperbranched epichlorohydrin/dimethylamine copolymers, polydiallyldimethylammonium chloride—were tested toward Gram-positive and Gram-negative cells. The polymers showed a significant biocidal effect in both aqueous solution and after formation of polymer films on the hydrophilic glass plates. Polymer films were almost completely removed by water during 10 wash-off cycles, that finally resulted in the ultrathin monolayers with a thickness of several nanometers. A polyethyleneimine film showed the most resistance to water with a 50% loss after three wash-off cycles and 75% loss after six wash-off cycles. Binding and subsequent deactivation of pathogenic microorganisms occurs on the outer surface of cationic polymer films. It is expected that a gradual polymer wash-off will allow renewal of the outer film surface and thereby restore the biocidal properties of the polycationic coatings, including those with a nanoscale thickness.

Study on the crushing strength improvement of artificial aggregates made with 100% solid wastes using polyvinyl alcohol solution

This study aimed to enhance the crushing strength of artificial aggregates (AAs) made with 100 wt% solid wastes using polyvinyl alcohol (PVA) solution. The effects of treatment methods (namely: mixing and coating) and different PVA dosages/concentrations on the properties of AAs were systematically investigated. The results show that using PVA solution mixing and coating treatment could considerably improve the crushing strength of AAs by about 99% and 69%, respectively. Adopting mixed treatment contributes to the formation of polymer films in AAs, which can fill the pores and enhance the bonding between particles. PVA coating treatment could form a layer of polymer film around AAs and enable the PVA to penetrate into the aggregate, filling the surrounding pores and bridging the aggregate matrix. It is found that the crushing strength of PVA-mixed aggregate with a dosage of 0.5 wt% could achieve comparable crushing strength compared with AAs coated with a high concentration (14%) of PVA. From a cost-effective perspective, the PVA mixing treatment with a dosage of 0.5 wt% is recommended for the crushing strength improvement of AAs. This study provides an effective method for enhancing the mechanical properties of AAs made from 100% solid wastes.

Measuring the ionic conductivity of solid polymer electrolyte powders

Ex-situ characterization of solid polymer electrolytes plays an important role in their development as materials for energy applications, with ionic conductivity being a crucial parameter to quantify. Conventional measurements of ionic conductivity often require the formation of a free-standing polymer film which in many instances is difficult to fabricate, thus there may be a need to quantify their ionic conductivity in powder form. In this work, we present a practical and reproducible method for measuring the ionic conductivity of solid polymer electrolytes (SPEs) in their powder form. By using a modified configuration of a through-plane cell, demonstrated with both a proton conducting- and an anion conducting-solid polymer electrolyte powder (SPEP), we are able to obtain ionic conductivity values under variable conditions in order to explore the influence of external parameters on the ionic conductivity of powders. Two types of SPEs in insoluble powder form were employed in this work: (1) a proton-exchange material (SPEP-H+) based on a hyperbranched, sulfo-phenylated poly(phenylene) SPEP (HB-sPPT-H+), with measured ionic conductivity of ⁓ 210 mS cm−1 at 80 °C and 95 % of relative humidity (RH); (2) an anion-exchange conducting polymer in its chloride form (SPEP-Cl-), consisting of a radiation-grafted ultra-high density polyethylene insoluble SPEP containing covalently-bonded benzyltrimethylammonium (BTMA) head-groups, with measured ionic conductivity of ⁓ 53 mS cm−1 at 80 °C and 95 % RH.

Polymer-based semiconductor wafer cleaning: The roles of organic acid, processing solvent, and polymer hydrophobicity

We propose a novel polymer-based cleaning technique to remove nanoparticles (<100 nm) from high-k and low-k wafers. Our method involves applying a polymer solution containing a hydrophobic polymer and organic acid onto the wafer surface, resulting in the formation of a nanoparticle-containing polymer film that can be peeled off. To ensure gentle removal of the film without wafer damage, we have developed a water-based “flake” method. Water penetrates the film through the organic acid, producing fine polymer flakes that can be easily removed along with the nanoparticles. Our systematic cleaning experiments involving diverse polymers, organic acids, and solvents on various nanoparticles and wafers demonstrate that polyvinylidene fluoride, a polymer with low surface energy, is exceptionally effective in nanoparticle removal due to its hydrophobic properties. Furthermore, it exhibits significant flake generation when exposed to water, thanks to its polymorphic characteristics, thereby exerting the most potent polymer-based cleaning effect. These experimental findings are consistent with our thermodynamic model simulations. This polymer-based cleaning technique provides a feasible solution to the long-standing environmental concerns associated with conventional semiconductor cleaning processes.

Detection of nitrification inhibitor dicyandiamide: A direct electrochemical approach.

A single run approach for rapid detection of nitrification inhibitor, dicyandiamide (DCD) using electrogenerated chlorine assisted polymerization through azo bond, under acidic conditions and at a preanodized screen printed carbon electrode (SPCE*) is presented. The role of chloride containing support electrolyte in acidic medium along with oxygen functionalities/edge sites are found to be crucial for the successful oxidative polymerization and subsequent adsorption of oxidized products on the electrode surface. The SEM, cyclic voltammetry and X-ray photoelectron spectroscopy studies were used to characterize the polymer film formation. The system exhibited a linear range between 20 and 170μM with a detection limit of 3μM (S/N=3). The method was successfully tested for the detection of DCD in dairy and water samples. Simultaneous detection of DCD in the presence of melamine has also been demonstrated.

Upcycling Waste Polycarbonate to Poly(carbonate imine) Vitrimers with High Thermal Properties and Unprecedented Hydrolytic Stability

The global market for polycarbonate (PC) increases steadily because of its heat resistance, toughness, and optical transparency. To achieve sustainability, the waste polycarbonate (WPC) should be recycled. This work reports a 100% atom-efficiency upcycling of WPC to a WPC-derived aldehyde (WPC-CHO). Then, poly(carbonate imine) vitrimers (PCIs) based on the WPC-CHO and two aromatic diamines were prepared. Generally, polyimines can cleave in mild acidic conditions such as 0.1 M HCl(aq) and seldom show good thermal and tensile properties. The PCIs in this work showed good thermal and tensile properties and an unprecedented resistance toward acid hydrolysis. They can survive even immersing in a 5 M H2SO4 THF/H2O solution for 6 months. This unusual resistance toward acid hydrolysis expands the application of PCIs in an acidic environment. Small pieces of PCIs can be compression-molded into a newly formed polymer film at 240 °C. This thermal reprocessability demonstrates the vitrimer characteristic of the PCIs. The PCIs can be degraded through simultaneous aminolysis of carbonate and transimination of imine by hexylamine (HA) in a catalyst-free mild condition. Based on the aminolysis and transimination, we degraded the cross-linking network in the PCI-based carbon fiber-reinforced polymer (CFRP) and recovered undamaged carbon fiber. This environmentally friendly work will attract the attention of researchers who are interested in sustainability and circularity.

Revealing the formation process of extra capacitance in Fe3O4/Li batteries with the first-principles study

The formation of extra capacitance in Fe3O4/Li batteries can be comprehended by utilizing the in situ magnetometry method. Nevertheless, the precise mechanism behind this phenomenon remains elusive. In this study, we adopt Li x O8/Fe to investigate the formation process of extra capacitance in Fe3O4/Li batteries from a microscopic and quantitative viewpoint. The Fe0 atoms exhibit an enhanced capability to store extra charge during the Li16O8/Fe process, and has significantly contributes to the magnetization of the batteries. Furthermore, we provide an accurate description of the process from the storage of excess electrons to the formation of polymer films. The outcomes of our research could potentially facilitate better control over the generation of additional capacitance.

Porous polymer film formation by water droplet templating using polystyrene.

Studies show that the formation of breath figures over polystyrene is not clearly understood-sometimes the patterns are regular and sometimes they are barely formed. In an attempt to understand this process a little more, breath figures over polystyrene of three molecular weights and on the smooth and grooved DVD surfaces are prepared and studied. The microporous films are prepared by the evaporation of the chloroform solution of the polymers in a humid environment. The thus formed breath figure patterns are studied under a confocal laser scanning microscope and the images are analyzed. Breath figures were formed for (a) three molecular weights of the polymer (b) two casting techniques, and (c) on smooth and grooved surfaces (of a commercial DVD). The wetting of the breath figures formed by water is also reported here. The pore diameters were found to increase with increase in molecular weight and also with concentration of the polymer used. Only drop-casting method yield breath figures. Voronoi entropy, calculated from the images, indicates ordered pores on the grooved surface compared to smooth surfaces. Contact angle studies indicate a hydrophobic nature of the polymer, with the hydrophobicity increasing by the patterning.

Effect of EVA Polymer and PVA Fiber on the Mechanical Properties of Ultra-High Performance Engineered Cementitious Composites

In order to study the mechanical properties of ultra-high performance engineered cementitious composites (UHP-ECC) used for cable channel repair, orthogonal tests were carried out with four influencing factors, water binder ratio, silica fume, fly ash and mortar ratio, to obtain the optimum mix ratio of the cement paste. On this basis, the effects of ethylene-vinyl acetate (EVA) polymer and polyvinyl alcohol (PVA) fiber on the fluidity, flexural strength and compressive strength of UHP-ECC were studied, and the micromechanism was analyzed with SEM. The results show that the fluidity of UHP-ECC material prepared was 170-200 mm, which meets the requirements of working performance. The average compressive strength at 28 days reached 85.3 MPa, and the average flexural strength at 28 days reached 22.3 MPa. EVA polymer has a fast film forming rate in an alkaline environment. The formed polymer film wraps the fiber, enhances the bridging role between the fiber and the matrix and increases the viscosity of the material. Therefore, the early flexural strength is significantly improved. The 1-d flexural strength of UHP-ECC material mixed with 9-mm fiber is increased by 18%, and the 1-d flexural strength of 3-mm fiber is increased by 15%. Due to PVA fiber's high elastic modulus and tensile strength, it improved the flexural and tensile properties of the material after incorporation, especially in the later stages; the 28-d flexural strength of UHP-ECC material mixed with 9-mm fiber increased by 12%, and the 28-d flexural strength of 3-mm fiber increased by 7%. It was concluded that the effect of 9-mm PVA fiber is better than that of 3 mm PVA fiber.

Glass formation and dynamics of model polymer films with one versus two active interfaces.

Polymers and other glass-forming liquids can exhibit profound alterations in dynamics in the nanoscale vicinity of interfaces, over a range appreciably exceeding that of typical interfacial thermodynamic gradients. The understanding of these dynamical gradients is particularly complicated in systems with internal or external nanoscale dimensions, where a gradient nucleated at one interface can impinge on a second, potentially distinct, interface. To better understand the interactions that govern system dynamics and glass formation in these cases, here we simulate the baseline case of a glass-forming polymer film, over a wide range of thickness, supported on a dynamically neutral substrate that has little effect on nearby dynamics. We compare these results to our prior simulations of freestanding films. Results indicate that dynamical gradients in our simulated systems, as measured based upon translational relaxation, are simply truncated when they impinge on a secondary surface that is locally dynamically neutral. Altered film behavior can be described almost entirely by gradient effects down to the thinnest films probed, with no evidence for finite-size effects sometimes posited to play a role in these systems. Finally, our simulations predict that linear gradient overlap effects in the presence of symmetric dynamically active interfaces yield a non-monotonic variation of the whole free standing film stretching exponent (relaxation time distribution breadth). The maximum relaxation time distribution breadth in simulation is found at a film thickness of 4-5 times the interfacial gradient range. Observation of this maximum in experiment would provide an important validation that the gradient behavior observed in simulation persists to experimental timescales. If validated, observation of this maximum would potentially also enable determination of the dynamic gradient range from experimental mean-film measurements of film dynamics.

N,S-heterocyclic carbene containing benzothiazol-2-ylidene-Ru(II) and Pd(II) new complexes functionalized with butyl linked carbazole moiety: Synthesis, characterization and their catalytic efficiency and electropolymerizations

In contrast to the large number of polymeric N-heterocyclic carbenes (NHCs) there are relatively few examples of NHCs-containing conductive polymers. However, conducting polymers (CPs) could be excellent hosts for NHC compounds, as they can easily form polymer films electrochemically, and their optical & electrical properties can be easily tuned by electrochemically or changing bonding groups in their structure. In this work, the N,S-heterocyclic carbene (NHC) ligand precursor, N-(4-butylcarbazole)benzothiazolium bromide (1) was prepared by solvent-free alkylation of benzothiazole by 9-(4-bromobutyl)carbazole with high efficiency. The air- and moisture-stable new piano-stool Ru(II)-N,S-NHC (2) and PEPPSI type Pd(II)-N,S-NHC (3) complexes, were synthesized and characterized by 1H- and 13C NMR, FT-IR, UV–vis and ESI-MS spectroscopic methods and elemental analysis. Further confirmations of structural details for benzothiazolium salt (1) and its Ru(II)-N,S-NHC complex (2) were determined by X-ray single-crystal diffraction. The catalytic performance of the complexes (2 and 3) in transfer hydrogenation (TH) of acetophenone and Suzuki–Miyaura cross-coupling reactions of aryl bromides were also investigated, respectively. All compounds (1–3) were electrochemically polymerized and conducting polymer films with pendant carbene complex moieties were obtained. The electrical and optical properties of the resulting polymers were characterized via spectroelectrochemical studies.

Chitosan: A Promising Multifunctional Cosmetic Ingredient for Skin and Hair Care

The cosmetic industry has an undeniable need to design and develop new ecosustainable products to respond to the demands of consumers and international regulations. This requires substituting some traditional ingredients derived from petrochemical sources with new ones with more ecofriendly profiles. However, this transition towards the use of green ingredients in the cosmetic industry cannot compromise the effectiveness of the obtained products. Emerging ingredients in this new direction of the cosmetic industry are chitosan and its derivatives, which combine many interesting physicochemical and biological properties for the fabrication of cosmetic products. Thus, the use of chitosan opens a promising future path to the design of cosmetic formulations. In particular, chitosan’s ability for interacting electrostatically with negatively charged substrates (e.g., skin or damaged hair), resulting in the formation of polymeric films which contribute to the conditioning and moisturizing of cosmetic substrates, makes this polymer an excellent candidate for the design of skin and hair care formulations. This review tries to provide an updated perspective on the potential interest of chitosan and its derivatives as ingredients of cosmetics for skin and hair care.