Polymer Substrates Research Articles

Deep‐Learning‐Assisted Affinity Classification for Humoral Immunoprotein Complexes

Immunoglobulins are important building blocks in biology and biotechnology. With the emergence of comprehensive deep‐learning approaches, there are enormous opportunities for fast and accurate methods of classification of protein–protein interactions to arise. Herein, widely accessible image classification algorithms for species‐specific typification of a range of different immunoglobulin G (IgG) complexes are repurposed. Droplets of various immunoglobulins mixed with a B‐cell superantigen (SAg) (recombinant staphylococcal Protein A) are deposited onto hydrophobic polymer substrates and the resulting protein stains are imaged using polarized light microscopy. A comprehensive study based on 23 745 images finds that the pretrained convolutional neural network (CNN) InceptionV3 not only successfully categorizes IgGs from four different species but also predicts their binding affinity to Protein A: averaged over 36 binding pairs, the following are observed: 1) an overall accuracy of 81.4%, 2) the highest prediction accuracy for human IgG, the antibody with the highest binding affinity for Protein A, and 3) that the classification accuracy regarding the various IgG/Protein A ratios generally correlates with the binding strength of the protein–protein–complex as determined via circular dichroism spectroscopy. In addition, the CNN pretrained with IgG/Protein A stain images has been challenged with a new set of images using a different superantigen (SAg, Protein G). Despite the use of the unknown SAg, the CNN correctly classifies the images of human IgG and Protein G as indicated by a 94% accuracy over the various molar binding ratios. These findings are noteworthy because they demonstrate that appropriately pretrained CNNs can be used for the prediction of protein–protein interactions beyond the scope of the original training set. Aided by deep‐learning methods, simple stains of mixed protein solutions may serve as accurate predictors of the strength of protein–protein interactions with relevance to protein engineering, self‐aggregation, or protein stability in complex media.

Substrate influence on the surface glass transition temperature of polymers

Enhanced molecular mobility near the free (polymer–air) surface is crucial for advancing organic electronic devices, yet understanding the substrate's impact on the surface glass transition temperature (Tgsurf) as film thickness decreases remains limited. This study explores how polymer films possessing attractive, neutral, and unfavorable polymer–substrate interactions affect Tgsurf. Results show that neutral interactions have no effect, while attractive or unfavorable interactions can increase or decrease Tgsurf by up to ∼37 °C. The onset thickness for this change is smaller for attractive interactions (up to 37 nm) than for unfavorable interactions (>100 nm), supporting the observed broadening of the surface glass transition with attractive interactions. We surmise that segment exchange between surface and subsurface regions introduces disparate dynamic components at the surface. Therefore, attractive interactions causing a sharper change in Tgsurf with film thickness lead to a broader surface glass transition.

Martensitic phase mechanism of ternary FeCrMn thin films influenced by the substrate rotation speeds: structural and magnetic properties

In order to investigate the martensitic phase mechanism of the ternary FeCrMn thin films sputtered under the effect of substrate rotation speeds, the structural and related magnetic properties were studied. A range of thin films were deposited at varying rotational speeds of 0, 15, 30, and 45 rpm on flexible amorphous polymer substrates through the use of DC magnetron sputtering. The films were 50 nm thick and were produced at 0.09 nm s−1. The crystal structures showed that all films have a mixture of the body-centred tetragonal (bct) and tetragonal structure. The peak intensity of bct (110) martensitic α’phase increased with the increase of the rotation speeds whereas the tetragonal (430) and (333) peaks stayed almost stable. And, the morphologic surface analysis displayed that the smooth surface turned into a rough surface with the increase of the rotation speeds. After the measurements of hysteresis loops, the films obtained by sputtering of austenitic target have ferromagnetic character with increasing saturation magnetization, MS and coercivity, HC as the substrate rotation speeds increase. With increasing rotation speeds, the increase of the MS from 148 to 242 emu cm−3 and the rise of the HC of the films from 21 to 185 Oe might be explained by the increase of the grain sizes with the increase of % martensitic α’phase caused by increasing rotation speeds. The ternary FeCrMn thin films exhibit increasing % martensitic α’phase and corresponding ferromagnetic properties with increasing substrate rotation speeds. It is concluded that the nanostructured films of FeCrMn have different properties from those of their bulk counterparts under the influence of substrate rotation speeds. Therefore, the martensitic mechanism of the films can easily be controlled by changing rotation speed for potentially flexible new device applications such as spintronics, magnetic hetero-structures, magnetic separators, etc.

In Situ Growth of Highly Compatible Cu2O-GO Hybrids Via Amino-Modification for Melt-Spun Efficient Antibacterial Polyamide 6 Fibers.

Polyamide 6 (PA6) fiber has the advantages of high strength and good wear resistance. However, it is still challenging to effectively load inorganic antibacterial agents into polymer substrates without antimicrobial activity. In this work, graphene oxide is used as a carrier, which is modified with an aminosilane coupling agent (AEAPTMS) to enhance the compatibility and antimicrobial properties of the inorganic material, as well as to improve its thermal stability in a high-temperature melting environment. Cuprous oxide-loaded aminated grapheme (Cu2O-GO-NH2) is constructed by in situ growth method, and further PA6/Cu2O-GO-NH2 fibers are prepared by in situ polymerization. The composite fiber has excellent washing resistance. After 50 times of washing, its bactericidal rates against Bacillus subtilis and Escherichia coli are 98.85% and 99.99%, respectively. In addition, the enhanced compatibility of Cu2O-GO-NH2 with the PA6 matrix improves the orientation and crystallinity of the composite fibers. Compared with PA6/Cu2O-GO fibers, the fracture strength of PA6/Cu2O-GO-NH2 fibers increases from 3.0 to 4.2 cN/dtex when the addition of Cu2O-GO-NH2 is 0.2wt%. Chemical modification and in situ concepts help to improve the compatibility of inorganic antimicrobial agents with organic polymers, which can be applied to the development of medical textiles.

Sol–gel prepared ZnO: UV irradiation effect on structure and surface properties

The effect of UV irradiation on sol–gel prepared ZnO films subjected to mild thermal annealing was investigated, with special attention to their structural and surface properties. Sol–gel processes, including a high-temperature annealing stage, have been adapted to the requirements of flexible electronics for in situ synthesis of semiconductor ZnO films on polymer substrates at lower temperatures due to UV irradiation. Application of UV radiation with emission peaks at 185 and 254 nm to films annealed at 180 °C made it possible to obtain ZnO films with Zn/O ratios of ca. 1, which cannot be achieved by heat treatment alone.

Novel Highly Hydrophilic Resins with Attached Polymer Layers for Liquid Chromatography

The aim of this work was to the obtaining novel mixed-mode stationary phases with increased hydrophilicity and applying them in ion and hydrophilic interaction liquid chromatography. The resins were obtained by the sequential covalent attachment of branched polyethylenimine and polyelectrolytes synthesized from diepoxide and a secondary amine on the surface of epoxidized polystyrene–divinylbenzene. To increase the shielding degree of the polymer substrate, an additional polymerization of glycidol was carried out in the functional layer of the sorbent at an increased pH of the reaction medium. The synthesized phases possessed increased hydrophilicity compared to most resins based on a styrene–divinylbenzene copolymer with covalently attached layers. This was evidenced in the ion chromatography mode by a decrease in the relative retention of polarizable anions, weakly hydrated oxyhalides (up to a change in the elution order of the bromate), and haloacetic acids. In the hydrophilic interaction liquid chromatography mode, an increased hydrophilicity of the phases was confirmed by an increase in the retention factors of polar analytes, as well as by the reversal of the elution order of ascorbic and nicotinic acids as compared to the phases based on polystyrene–divinylbenzene presented in the literature. The low efficiency of the obtained stationary phases in the ion chromatography mode was noted, which is associated with slow mass transfer in the bulk polymer functional layer. The negative impact of the polymer layer on efficiency in hydrophilic interaction liquid chromatography is less pronounced due to the presumably smaller thickness of the part of the functional layer involved in this mode. The proposed method for the synthesis of resins ensures an increase in the efficiency, selectivity, and separation ability of sorbents in the hydrophilic interaction liquid chromatography mode as compared to phases based on a styrene–divinylbenzene copolymer described previously in the literature. The resulting highly hydrophilic resins makes it possible to separate a mixture of 9 nitrogenous bases and nucleosides in 18 min, 6 vitamins in 24 min, and 8 sugars in 11 min. Thus, the method of substrate hydrophilization proposed in this work is promising for improving the chromatographic characteristics of phases in the hydrophilic interaction liquid chromatography mode and can be used to create sorbents with increased selectivity and efficiency.

Polydopamine-assisted minute fabrication of vertically aligned ZIF-L membranes for CO2/N2 separations

Metal-organic framework (MOF) membranes demonstrate significant potential for industrial gas separations, yet fabricating vertically aligned two-dimensional (2D) MOF membranes on polymer substrates remains a considerable challenge due to the weak adhesion and difficulty in achieving precise alignment. This study presents a one-step method for the rapid synthesis of vertically aligned ZIF-L membranes, using a polydopamine (PDA)-assisted approach. This method enables the rapid formation of homogenous, thin but defect-free membranes on polymer substrates within 5 min, drastically reducing the preparation time by over 200 times. The vertically aligned ZIF-L membranes, characterized by the interlayer galleries facing the gas mixtures, exhibit an excellent CO2 permeance exceeding 1200 GPU and a CO2/N2 selectivity of 14.5. The versatility of this approach allows for its application on various flat-sheet or even hollow fiber supports. Our findings highlight the potential of PDA-assisted synthesis for efficient, scalable preparation of high-performance MOF membranes for industrial gas separations.

Iterative printing of bulk metal and polymer for additive manufacturing of multi-layer electronic circuits

In pursuing advancing additive manufacturing (AM) techniques for 3D objects, this study combines AM techniques for bulk metal and polymer on a single platform for one-stop printing of multilayer 3D electronic circuits with two novel aspects. The first innovation involves the embedded integration of electronic circuits by printing low-resistance electrical traces from bulk metal into polymer channels. Cross-section grinding results reveal (92 ± 5)% occupancy of electrically conductive traces in polymer channels despite the different thermal properties of the two materials. The second aspect encompasses the possibility of printing vertical bulk metal vias up to 10 mm in height with the potential for expansion, interconnecting electrically conductive traces embedded in different layers of the 3D object. The work provides comprehensive 3D printing design guidelines for successfully integrating fully embedded electrically conductive traces and the interconnecting vertical bulk metal vias. A smooth and continuous workflow is also introduced, enabling a single-run print of functional multilayer embedded 3D electronics. The design rules and the workflow facilitate the iterative printing of two distinct materials, each defined by unique printing temperatures and techniques. Observations indicate that conductive traces using molten metal microdroplets show a 12-fold reduction in resistance compared to nanoparticle ink-based methods, meaning this technique greatly complements multi-material additive manufacturing (MM-AM). The work presents insights into the behavior of molten metal microdroplets on a polymer substrate when printed through the MM-AM process. It explores their characteristics in two scenarios: When they are deposited side-by-side to form conductive traces and when they are deposited out-of-plane to create vertical bulk metal vias. The innovative application of MM-AM to produce multilayer embedded 3D electronics with bulk metal and polymer demonstrates significant potential for realizing the fabrication of free-form 3D electronics.

One-step visible laser writing of Cu-doped graphene hybrid structure for in-plane supercapacitor assembly

High-quality copper-graphene holds great potential for applications in electronics, but fabricating these hybrid structures in a cost-effective route remains challenging. Herein, we propose a one-step writing process for manufacturing copper-doped graphene hybrid structure using low-cost visible laser. The ionic precursor coated on the surface of polymeric substrate not only acts as a copper source for doping, but also can promote near-surface graphenization of the polymer as proved in this study. The interaction between copper and graphene during this in-situ laser processing has been in-deep discussed to reveal the formation mechanism of the hybrid structure. The obtained hybrid structure shows excellent performance that can assemble high-performance devices, such as the in-plane supercapacitor we demonstrated. This study presents a low-cost, rapid, and efficient strategy for structuring the composites to meet the demands for high-performance structures in booming electronics.

(Alumina and graphene)/ PLA nanocomposites manufactured by digital light processing 3D printer

In this study, the variant effects of alumina and graphene reinforcing nanoparticle percentages on the tensile and wear properties of the nanocomposites, produced using digital light processing (DLP), were determined by employing SEM images of fracture and worn surfaces to introduce a hybrid (alumina + graphene)/PLA nanocomposite with desirable wear and mechanical properties. With the addition of alumina up to 2 wt%, the tensile strength was initially decreased exhibiting a rapid brittle fracture over the flat fracture surface. However, with a continued increase in the amount of reinforcing particles, the tensile strength eventually increased by 16% compared to the pure resin sample at 8 wt% of alumina while changing the fracture mode with plenty of cleavages accompanied by crack deflections. The specific wear rate in the 8 wt% alumina sample decreased by almost 62% compared to the pure resin sample. Graphene caused a significant drop in tensile strength due to the generation of cavities and porosities around the graphene agglomerates, but it greatly improved the wear properties, with the specific wear rate decreasing by almost 77% at just 1 wt%. Then hybrid nanocomposites of alumina and graphene reinforcements were produced with the aim of optimal tensile and wear properties. The 0.5% graphene +3.5% alumina improved the wear resistance and provided moderate tensile properties; however, the 1% graphene +3% alumina could not increase the wear resistance due to the weakening of graphene plates sticking to the polymer substrate.

A cationic three-dimensional covalent organic framework membrane for nanofiltration of molecules and rare Earth ions

Permanently microporous materials have evolved as focal point of research for tackling issues in separation science and membrane technology. Covalent organic frameworks (COFs) stand out for their distinctive synergy of crystalline nature, uniform channels, and structural diversities. Three-dimensional (3D) COFs, distinguished by angstrom-sized and interconnected channels, hold special promise for separating small targets; however, this potential remains underexplored. Here, we report feasible growth of cationic 3D COF membranes on a flexible polymer substrate for versatile nanofiltration toward both molecules and ions. Through comprehensive performance evaluations, we reveal that the resultant membrane exhibits durable and prominent molecular selectivity to separate fine species with molecular weights above 300 g mol−1 at fast methanol permeation. Lanthanide ions of industrial value also can be harvested by the membrane with rejection rates of up to 91.4%. Together with its nonselectivity to competing ions, our membrane implements efficient extraction of rare earth elements from ion mixtures. These findings illuminate the potential of 3D COFs for liquid separation and offer a solution to building versatile membranes.

Functionalization of Polypropylene by TiO2 Photocatalytic Nanoparticles: On the Importance of the Surface Oxygen Plasma Treatment.

A new two-step method for developing a nanocomposite of polypropylene (PP) decorated with photocatalytically active TiO2 nanoparticles (nTiO2) is proposed. This method involves the low-temperature plasma functionalization of polypropylene followed by the ultrasound-assisted anchoring of nTiO2. The nanoparticles, polymeric substrate, and resultant nanocomposite were thoroughly characterized using nanoparticle tracking analysis (NTA), microscopic observations (SEM, TEM, and EDX), spectroscopic investigations (XPS and FTIR), thermogravimetric analysis (TG/DTA), and water contact angle (WCA) measurements. The photocatalytic activity of the nanocomposites was evaluated through the degradation of methyl orange. The individual TiO2 nanoparticles ranged from 2 to 6 nm in size. The oxygen plasma treatment of PP generated surface functional groups (mainly -OH and -C=O), transforming the surface from hydrophobic to hydrophilic, which facilitated the efficient deposition of nTiO2. Optimized plasma treatment and sonochemical deposition parameters resulted in an active photocatalytic nTiO2/PP system, degrading 80% of the methyl orange under UVA irradiation in 200 min. The proposed approach is considered versatile for the functionalization of polymeric materials with photoactive nanoparticles and, in a broader perspective, can be utilized for the fabrication of self-cleaning surfaces.

Templated Nucleation of Clotrimazole and Ketoprofen on Polymer Substrates.

The use of different template surfaces in crystallization experiments can directly influence the nucleation kinetics, crystal growth, and morphology of active pharmaceutical ingredients (APIs). Consequently, templated nucleation is an attractive approach to enhance crystal nucleation kinetics and preferentially nucleate desired crystal polymorphs for solid-form drug molecules, particularly large and flexible molecules that are difficult to crystallize. Herein, we investigate the effect of polymer templates on the crystal nucleation of clotrimazole and ketoprofen with both experiments and computational methods. Crystallization was carried out in toluene solvent for both APIs with a template library consisting of 12 different polymers. In complement to the experimental studies, we developed a computational workflow based on molecular dynamics (MD) and derived descriptors from the simulations to score and rank API-polymer interactions. The descriptors were used to measure the energy of interaction (EOI), hydrogen bonding, and rugosity (surface roughness) similarity between the APIs and polymer templates. We used a variety of machine learning models (14 in total) along with these descriptors to predict the crystallization outcome of the polymer templates. We found that simply rank-ordering the polymers by their API-polymer interaction energy descriptors yielded 92% accuracy in predicting the experimental outcome for clotrimazole and ketoprofen. The most accurate machine learning model for both APIs was found to be a random forest model. Using these models, we were able to predict the crystallization outcomes for all polymers. Additionally, we have performed a feature importance analysis using the trained models and found that the most predictive features are the energy descriptors. These results demonstrate that API-polymer interaction energies are correlated with heterogeneous crystallization outcomes.

SRIM simulation of hydrogen ions interaction with bismuth oxide nanoparticles doped with rare earth elements

Simulation methods have received much attention across various fields in recent years. The rare-earth lutetium tantalate (LuTaO4) doped “Bismuth Oxide (Bi2O3) thin films were deposited onto polymer substrates using a SRIM program.” The SRIM program was used to calculate some physical characteristics of Bi2O3 films at energies between 1.0 MeV and 20 MeV. The “electronic and nuclear stopping powers” of LuTaO4, Bi2O3, C10H8O4, and LuTaO4/ Bi2O3/C10H8O4 samples were investigated. These findings show that rare earth doping may improve the performance of composite materials. The interaction of ion beams with matter can result in a wide variety of phenomena. The deposition of Bi2O3 films doped with LuTaO4 on C10H8O4 led to changes in the “electronic and nuclear stopping powers” and range in the materials. Published data were compared with the results obtained and the calculations parameters were provided.

MIL-125 (Ti) and porous dielectric polymer substrate introducing composite gel polymer electrolyte with enhanced mechanical property, thermal stability and electrochemical property

Lithium metal batteries have potentially high energy density, but severe uncontrolled lithium dendrites and unstable side reactions prevent large-scale applications. Serial three-dimensional porous poly (vinylidene fluoride) and copolymer membrane-based composite gel electrolytes are designed by introducing MIL-125 (Ti) and ethylene carbonate. Abundant lithium-ion transportation channels and homogeneous ion transport microregion are provided the new type porous fluoropolymer substrate. We also find that crystalline phase and dielectric properties of serial polymer membrane have significant impact on electrochemical performance for composite gel electrolytes. The mechanical and dielectric property of composite electrolyte enhanced by incorporating uniform and well distribution MIL-125 (Ti), which improve the electrolyte/electrode interface charge distribution and promote uniform lithium deposition, leading to lithium dendrite suppression. MIL-125 (Ti)/P(VDF-TrFE-CTFE) composite membrane shows the enhanced maximum strain of 181 %, thermal stability (188 °C) and corresponding composite gel electrolyte reflects higher ionic conductivity of 1.7 × 10–3 S cm-1 and wider electrochemical window at room temperature than PVDF and PVDF-HFP composite electrolytes. Expectedly, quasi-solid state lithium metal battery of MIL-125 (Ti)/P(VDF-TrFE-CTFE) composite gel electrolyte exhibits higher discharge capacity (152.8 mAh g-1) at 240th cycle and 1 C, longer cycling life and better rate performance under large current density than PVDF and PVDF-HFP composite electrolytes.

Fabrication of mixed matrix membranes based on PVDF matrix and ZrT-1-NH2 filler for efficient adsorptive removal of Orange G

Adsorption membranes have become a hot spot for wastewater treatment in recent years. Due to the lack of active sites in traditional inert materials such as polyvinylidene fluoride (PVDF) membranes, it is difficult to bind pollutants in water with high affinity. Therefore, in this study, ZrT-1-NH2/PVDF mixed matrix membranes (MMMs) were prepared by combining an amino-functionalized Zr-based metal–organic cage (ZrT-1-NH2) with a polymer substrate via non-solvent-induced phase separation method for the efficient removal of Orange G (OG) from water. This method has many advantages such as simplicity in operation, high applicability, controllable MOFs loading. The structural characteristics and adsorption properties and of MMMs were also investigated through a series of characterizations and experiments. The result shows that in a 100 mL OG solution with an initial concentration of 50 mg/L and pH=3, M60 exhibited significant adsorption capacity, the removal efficiency reached 97.23 %, with an adsorption capacity of 64.18 mg/g, which is much higher than the pristine PVDF membrane. It is mainly attributed to electrostatic interactions and hydrogen bonding interactions between ZrT-1-NH2 and OG molecules. This is consistent with the DFT calculations. The introduction of ZrT-1-NH2 filler improves the performance of PVDF membranes and expands their potential applications.

Optimization of Hot Embossing Condition Using Taguchi Method and Evaluation of Microchannels for Flexible On-Chip Proton-Exchange Membrane Fuel Cell.

Hot embossing is a manufacturing technique used to create microchannels on polymer substrates. In recent years, microchannel fabrication technology based on hot embossing has attracted considerable attention due to its convenience and low cost. A new evaluation method of microchannels, as well as an approach to obtaining optimal hot embossing conditions based on the Taguchi method, is proposed in this paper to fabricate precise microchannels for a flexible proton-exchange membrane fuel cell (PEMFC). Our self-made hot embossing system can be used to fabricate assorted types of micro-channel structures on polymer substrates according to various applications, whose bottom width, top width, height and cross-sectional area vary in the aims of different situations. In order to obtain a high effective filling ratio, a new evaluation method is presented based on the four parameters of channel structures, and the Taguchi method is utilized to arrange three main factors (temperature, force and time) affecting the hot embossing in orthogonal arrays, quickly finding the optimal condition for the embossing process. The evaluation method for microchannels proposed in this paper, compared to traditional evaluation methods, incorporates the area factor, providing a more comprehensive assessment of the fabrication completeness of the microchannels. Additionally, it allows for the quick and simple identification of optimal conditions. The experimental results indicate that after determining the optimal embossing temperature, pressure and time using the Taguchi method, the effective filling rate remains above 95%, thereby enhancing the power density. Through variance analysis, it was found that temperature is the most significant factor affecting the hot embossing of microchannels. The high filling rate makes the process suitable for PEMFCs. The results demonstrate that under optimized process conditions, a self-made hot embossing system can effectively fabricate columnar structure microchannels for PEMFCs.

Design and Construction of Highly Luminescent Transparent Woody Materials Exhibiting Unique Fluorescence-Enhanced Staining Effects for Visualization of Intrinsic Microporous Networks.

Luminescent wood materials are an emerging class of biomass hybrid host materials owing to the hierarchical porous structure and functionalization versatility. The fluorescence properties are largely dependent on exogenous fluorophores, which are, however, often plagued by notorious aggregation effects. In this work, an efficient strategy for the preparation of luminescent transparent wood materials is developed by incorporating tetraphenylethylene-derived aggregation-induced emission (AIE)-active fluorophores during a delignification-backfill transparency process. These wood hybrids showed unexpected luminescence enhancement that significantly increased the fluorescence quantum yield of the fluorophores up to 99%, much higher than that of the fluorophores in other states such as crystalline solids or doped in a polymer substrate. Mechanistic investigations reveal that in situ polymerization of prepolymerized methyl methacrylate in delignified microporous wood frames produces high molecular weight ordered PMMA polymers, resulting in a rigid molecular environment that improves the luminescence efficiency of TPE-based fluorophores at the interfaces of PMMA polymer and cell walls. By confocal laser scanning microscopy (CLSM), this excellent fluorescence staining capability was furthermore utilized to visualize the intrinsic porous network of wood in three dimensions over a large volume with submicrometer resolution, thus providing an alternative approach to the study of structure-function relationships in such wood hybrids.

Tuning the Permeation Properties of Poly(1‐trimethylsilyl‐1‐propyne) by Vapor Phase Infiltration Using Trimethylaluminum

AbstractVapor phase infiltration (VPI) has emerged as a promising tool for fabrication of novel hybrid materials. In the field of polymeric gas separation membranes, a beneficial impact on stability and membrane performance is known for several polymers with differing functional groups. This study for the first time investigates VPI of trimethylaluminum (TMA) into poly(1‐trimethylsilyl‐1‐propyne) (PTMSP), featuring a carbon–carbon double bond as functional group. Saturation of the precursor inside the polymer is already attained after 60 s infiltration time leading to significant densification of the material. Depth profiling proves accumulation of aluminum in the polymer itself, but a significantly increased accumulation is visible in the gradient layer between polymer and SiO2 substrate. A reaction pathway is proposed and supplemented by density‐functional theory (DFT) calculations. Infrared spectra derived from both experiments and simulation support the presented reaction pathway. In terms of permeance, a favorable impact on selectivity is observed for infiltration times up to 1 s. Longer infiltration times yield greatly reduced permeance values close or even below the detection limit of the measurement device. The present results of this study set a strong basis for the application of VPI on polymers for gas‐barrier and membrane applications in the future.

An investigation of the electrical dynamics in electroactive polymer transducers with resistive electrodes

To pursue a variable-capacitance working principle, transducers based on soft electroactive polymers (EAPs) need deformable electrodes that match the compliance and stretchability of the EAP polymeric substrates. A variety of manufacturing procedures are available to create conductive materials that can achieve this, including solutions that can provide remarkably low resistivity. However, the simplest and most feasible options often involve the use of particle-filled (e.g. carbon-filled) polymer composites, which, while easy to produce, tend to exhibit relatively high resistivity. This high level of resistivity, combined with the inherent capacitance of EAP transducers, introduces dynamic effects in the devices electrical activation, which may affect performance. This paper investigates the impact of electrode resistivity on the electrical dynamics of EAP devices, combining continuum models and experimental validations. We use a continuum generalisation of known resistive-capacitive (RC) transmission line models to accurately predict voltage gradients on the surfaces of electrostatic transducers subject to rapidly varying voltages. We then present an experimental validation by measuring the spatial voltage distributions over carbon-based polymeric electrodes of dielectric elastomer (DE) transducers, and find a good agreement with our model predictions. We use our validated model to provide general estimates of the typical charging time and limit working frequency ranges of DE devices as a function of their dimensional scale and electrode sheet resistance. Our model provides useful indications for designing compliant electrodes in EAP transducers given target performance, or to understand the working limits of devices with given geometry and dielectric-electrode properties.