Polymer Surface Research Articles

Reversibly Switchable Magnetically Controlled Solid‐Liquid Triboelectric Nanogenerator Using Hierarchical Ecoflex/NdFeB Magnetic Polymer Surface

AbstractDroplet‐driven triboelectric nanogenerator (TENG) with reversible switching capability has been widespread concerned; particularly magnetically controlled solid‐liquid TENG, due to its fast and highly reversible responses. Herein, a hierarchical composite structured magnetic polymer surface (HCSMPS) is developed using template method and magnetic field induction, and construct a HCSMPS‐based TENG (HCSMPS‐TENG). The HCSMPS‐TENG shows different states—fallen, upright, and no magnetic field—when applying different magnetic fields. The wetting properties of HCSMPS under three states vary significantly. The current output of the HCSMPS‐TENG driven by deionized water and potassium chloride (KCl) solution varies across these states due to changes in the droplet contact area. As KCl concentration increases, the current signals of the HCSMPS‐TENG initially rise due to the increased free charges but subsequently decrease due to a screening effect caused by ion adsorption. For practical application, a real‐time monitoring system is developed for KCl concentration based on the HCSMPS‐TENG, integrating a convolutional neural network. This system, equipped with a compact current collection circuit capable of remote data transmission and a user‐friendly interface developed with LabVIEW, achieves 98.64% recognition accuracy. The HCSMPS‐TENG is applied to intravenous potassium supplementation, demonstrating its potential for medical KCl concentration and infusion flow rate monitoring.

Correction to “Sonochemical Formation of Fluorouracil Nanoparticles: Toward Controlled Drug Delivery from Polymeric Surfaces”

Correction to “Sonochemical Formation of Fluorouracil Nanoparticles: Toward Controlled Drug Delivery from Polymeric Surfaces”

Polymers in Physics, Chemistry and Biology: Behavior of Linear Polymers in Fractal Structures.

We start presenting an overview on recent applications of linear polymers and networks in condensed matter physics, chemistry and biology by briefly discussing selected papers (published within 2022-2024) in some detail. They are organized into three main subsections: polymers in physics (further subdivided into simulations of coarse-grained models and structural properties of materials), chemistry (quantum mechanical calculations, environmental issues and rheological properties of viscoelastic composites) and biology (macromolecules, proteins and biomedical applications). The core of the work is devoted to a review of theoretical aspects of linear polymers, with emphasis on self-avoiding walk (SAW) chains, in regular lattices and in both deterministic and random fractal structures. Values of critical exponents describing the structure of SAWs in different environments are updated whenever available. The case of random fractal structures is modeled by percolation clusters at criticality, and the issue of multifractality, which is typical of these complex systems, is illustrated. Applications of these models are suggested, and references to known results in the literature are provided. A detailed discussion of the reptation method and its many interesting applications are provided. The problem of protein folding and protein evolution are also considered, and the key issues and open questions are highlighted. We include an experimental section on polymers which introduces the most relevant aspects of linear polymers relevant to this work. The last two sections are dedicated to applications, one in materials science, such as fractal features of plasma-treated polymeric materials surfaces and the growth of polymer thin films, and a second one in biology, by considering among others long linear polymers, such as DNA, confined within a finite domain.

Studying the Feasibility of Creating Anisotropic Highly Hydrophobic Polymer Surfaces by Ion-Track Technology

In the last two decades, the creation and research of superhydrophobic nanomaterials based on the “lotus effect” have attracted great interest. The effect is caused by the heterogeneous wetting of rough surfaces, when the grooves of a rough surface are filled with air (vapour) and water only contacts the tops of the protrusions. The drop forms a sphere on the surface and, if slightly inclined, rolls down and picks up the dirt particles. A wide variety of methods have been developed to produce such materials, among which potential of the ion track technology (ITT) is being explored. The aim of this research was to investigate the wettability of surface microrelief using two materials with different initial hydrophobicity degrees. By modifying the surface of polycarbonate and polypropylene films using the ITT, the samples with water contact angles of 140 ± 5° and 151 ± 5° at maximum, respectively, were obtained. It is shown that such angles are characteristic of microrelief, where the fraction f of the surface that is in contact with the droplet is decreased to the range 0 f 0.3. In order to increase the probability of droplets rolling down the material surface in a certain direction, the materials with inclined microrelief were obtained. In this case, the wettability becomes anisotropic. The droplet loses its spherical shape, deforming in the direction of inclination of needle-like surface elements. It was found that the anisotropy of wettability is higher at an inclination angle of the relief elements of 45° than that at 30° (relative to the flat surface).

Universal salt-assisted assembly of MXene from suspension on polymer substrates

Two-dimensional carbides and nitrides, known as MXenes, are promising for water-processable coatings due to their excellent electrical, thermal, and optical properties. However, depositing hydrophilic MXene nanosheets onto inert or hydrophobic polymer surfaces requires plasma treatment or chemical modification. This study demonstrates a universal salt-assisted assembly method that produces ultra-thin, uniform MXene coatings with exceptional mechanical stability and washability on various polymers, including high-performance polymers for extreme temperatures. The salt in the Ti3C2Tx colloidal suspension reduces surface charges, enabling electrostatically hydrophobized MXene deposition on polymers. A library of salts was used to optimize assembly kinetics and coating morphology. A 170 nm MXene coating can reduce radiation temperature by ~200 °C on a 300 °C PEEK substrate, while the coating on Kevlar fabric provides comfort in extreme conditions, including outer space and polar regions.

Coarse-Grained Modeling of the Water/Alkane Wetting and Dewetting Processes on Fluorinated Coatings.

This work provides a framework to digitally assess any droplet's static and dynamic contact angles on coatings and polymeric substrates. We are introducing a new dissipative particle dynamics coarse-grained model to attain the spatiotemporal conditions and the coexistence of different phases that such investigation dictates. Two computational techniques are additionally developed; a robust technique to calculate the static contact angle using density profiles and a perturbation method to evaluate dynamic contact angles. A parallel force to the surface force is applied to emulate the receding and advancing dynamics. We have validated our protocols for the static contact angle of water for a series of polymeric surfaces and the dynamic contact angle for three different fluorinated additives. We reproduced the correct hysteresis trends between the droplet content and the surface. The fluorinated nature of the additive's tails is the driving force of directed self-assembly and, consequently, the repelling nature of the surface. An equally important factor for designating the interaction profile of the surface is the coating's chemical structure, which is responsible for inhibiting or favoring the aqueous media interaction.

1D, 2D, and 3D Micropatterning of ZnO Nanoparticles and Nanorod by Two‐Photon Polymerization and Surface Functionalization

AbstractIn this paper, a novel method is proposed for selective deposition of ZnO nanoparticles (NPs) and growth of ZnO Nanorods (NRs) on multi‐dimensional patterned polymer surfaces. The method involves microfabrication of functionalized 1D, 2D, and 3D polymer structures by two‐photon polymerization (TPP) followed by selective assembly of ZnO NPs acting as seeds before growing ZnO NRs by chemical bath deposition (CBD) technique at low temperature. The immobilization of the ZnO NPs seed layer is done by electrostatic interaction between the positively charged polymer surface functionalized by amine groups and the negatively charged ZnO NPs functionalized by citrate molecules. The influence of citrate molecules on the stability of the ZnO NPs dispersions and their immobilization on the polymer surface is demonstrated. Spatially controlled and selective growth of ZnO NRs is shown at low temperatures on multi‐dimensional structures up to 9 mm2 and having different shapes, including 1D polymer lines, 2D microplates, and 3D arrays of cones. The diameter of NRs and their orientation can be controlled through the size of ZnO NPs and the shape of the polymer structure respectively.

Controllable and Facile Metallization of Polymer Surface with Biphasic Liquid Metals toward Soft Circuits.

Chemical metallization (e.g., chemical/electrical plating) of the polymer surface is an extremely important, convenient, cost-effective, and broadly applied strategy to realize combined advantages of functional metals and polymers for today's industry. However, traditional chemical and electrical metallization of polymer surfaces requires the participation of physical methods, which greatly constrains the utilization of versatile metals in modern electronics. This work successfully utilized a traditional chemical strategy to address the challenging preliminary conductivity and subsequent liquid metal (LM) metallization of insulated polymer surfaces. Through the facile strategy, an ultrathin (6 μm) LM film could be conveniently coated on both the external and internal surface of polymers to fabricate large-area flexible circuits with fine line width (15 μm) at low-cost (9.5 $·dm-2). A detailed reaction mechanism of the LMs was reported, and various chemical parameters of the metallization were thoroughly investigated. Interestingly, the metallized polymer surface showed a distinguished CuGa2/Ga biphasic structure of the LMs, which enabled the polymer as an extraordinarily soft conductor with ultrahigh uniaxial strain (>1200%), extremely low resistance variation (R/R0 < 7), strong metal-polymer adhesion (1.5 N·mm-1), and excellent electrical durability. Furthermore, with the benefit of the photolithography technique, precisely designed circuits could be achieved, and wireless transmission/control soft electronic devices were easily fabricated.

Selective-layer polysulfone membranes based on unfunctionalized and functionalized MoS2/polyamide nanocomposite for water desalination.

Recently, reverse osmosis (RO) has become the most widely used process in membrane technology. It has aroused great interest in water desalination through membranes. According to recent studies, the surface properties of support layers in thin film membranes are crucial for improving reverse osmosis performance. Surface polymerization was used to produce the membranes in this work, with the polyamide acting as a selective layer on the polysulfone support film. Three membranes were produced with different proportions of molybdenum sulfide (MoS2) nanopowder. The effectiveness of the membranes was improved by increasing water permeability while maintaining excellent salt retention. All membranes produced were tested using various characterization methods including scanning electron microscope, Brunauer-Emmett plate, and zeta potential. The water permeability of the polyamide membrane with PA-MoS2 (0.015% w/v) was 29.79 L/m2 h bar, more than the PA-MoS2 membranes (0.005% w/v, 19.36 L/m2 h) and PA-MoS2 (0.01% w/v, 3.63 L/m2 h bar). Under the same conditions, salt rejection of more than 96.0% for NaCl and 97.0% for MgSO4 was also observed. According to the SEM, the 0.015% PA-MoS2 membrane exhibited lower surface roughness, greater hydrophobicity, and a higher water contact angle. Due to the hydrophobic nature of MoS2, these properties resulted in the lowest salt rejection.

Easy-to-Engineer Flexible Nanoelectrode Sensor from an Inexpensive Overhead Projector Sheet for Sweat Neuropeptide-Y Detection.

In this paper, we report an inexpensive and easy-to-engineer flexible nanobiosensor electrode platform by exploring a nonconductive overhead projector (OHP) sheet for sweat Neuropeptide-Y (NPY) detection, a potential biomarker for stress, cardiovascular regulation, appetite, etc. We converted a nonconductive OHP sheet into a conductive nanobiosensor electrode platform with a hybrid polymerization method, which consists of interfacial polymerization of pyrrole and a template-free electropolymerization technique to decorate the electrode platform with poly(EDOT-COOH-co-EDOT-EG3) nanotubes. The selection of poly(EDOT-COOH) features an easy conjugation of NPY antibody (NPY-Ab) through EDC/Sulfo-NHS coupling chemistry, while poly(EDOT-EG3) is best known to reduce nonspecific binding of biomolecules. The antibody conjugation on the polymer surface was characterized by a quartz crystal microbalance, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and chronoamperometry techniques. The OHP nanosensor platform exhibited the successful detection of NPY analyte through a chronoamperometry method in phosphate-buffered saline with a wide range of concentrations from 1 pg/mL to 1 μg/mL with a limit of detection of 0.68 pg/mL having good linearity (R2 = 0.9841). The sensor platform exhibited excellent stability, reproducibility, repeatability, and a shelf-life of 13 days. Furthermore, the sensor showed superior selectivity to a 100 pg/mL NPY analyte among other interfering compounds such as tumor necrosis factor α, cortisol, and Interleukin-6. The clinical practicality of the sensor was confirmed through the detection of 100 pg/mL NPY spiked artificial perspiration, highlighting the possibility of integrating the sensor platform to wearable healthcare applications.

Formation Mechanism of Polypyrrole-Coated Hollow Glass Microspheres (PPy@HGMs) Composite Powder.

Coating conductive nanoparticles onto the surface of hollow glass microspheres (HGMs) is essential for broadening their applications. However, the low density and high specific surface area of HGM powders, along with the thin walls of the cavity shells and poor surface adhesion, pose challenges for the uniform attachment of functional particles. In this study, we developed a novel integrated process that combines flotation, hydroxylation, and amination pretreatment for HGMs with in situ surface polymerization to achieve a uniform coating of polypyrrole (PPy) on the surface of HGMs. We explored the corresponding growth process and coating mechanism. Our findings indicate that the amount of coating, particle size, and uniformity of PPy on the surface of HGMs are significantly influenced by the pretreatment and the in situ polymerization time, as well as the microspheres/pyrrole feedstock ratio. The in situ polymerization on the surface of HGMs resulted in a uniform encapsulation of spherical PPy, with the average particle size of PPy-coated HGMs (PPy@HGMs) increasing by 14.60% compared to the original HGMs. The elemental nitrogen in the PPy@HGMs primarily exists in the form of C-N and N-H bonds. This study demonstrates that the surface functional groups of HGMs engage in chemical bonding and interactions with PPy molecules. Mechanistic analysis reveals that the hydroxyl and amino groups enriched on the surface of the pretreated HGMs serve as activation centers, facilitating the uniform enrichment of pyrrole monomers and promoting chain growth polymerization of the conjugated chain through nucleophilic and electrophilic interactions with the subamino groups in the pyrrole ring. Additionally, the reaction between the Lewis acid properties of PPy and the Lewis-type electron-donating amino groups in KH550 fosters strong bonding and the formation of a robust interface.

Mechanistic Study of Atomic Oxygen Erosion on Polyimide Under Electric Fields: A Molecular Dynamics and Density Functional Theory Approach.

Polyimide (PI) is widely used in aerospace applications due to its superior insulating properties. However, the high concentration of atomic oxygen (AO) in low Earth orbit leads to significant performance degradation in PI, and the underlying mechanism of AO erosion under an electric field remains unclear. This study utilizes molecular dynamics simulations to model AO erosion on PI under various electric field strengths and explores the corresponding degradation mechanisms. The results indicate that the presence of an electric field exacerbates the degradation of PI by AO. AO erosion elevates the polymer's temperature, and the combined effects of thermal and electric stresses increase the polymer's free volume, loosening its structure and accelerating degradation. The quantity of AO-induced erosion products increases with rising electric field strength, causing more large carbon chains to detach from the polymer surface. Density functional theory (DFT) calculations further reveal that the electric field reduces the frontier orbital energy gap in PI molecules, making AO erosion reactions more thermodynamically favorable. This work provides an atomic-level insight into the degradation mechanism of PI under AO erosion in electric fields and offers a theoretical basis for future studies on polymer resistance to AO erosion in space environments.

Multi-Dimensionally Functionalized Pressure Sensor for Human Motion Detection Based on 1D AgNWs/2D rGO-Coated 3D Porous Sponge.

This study presents a conductive-type pressure sensor based on a conductive composite of 1D/2D nanomaterials coated onto a 3D nonconductive polymer structure with various pores. A 3D porous elastomer for the substrate was fabricated by using a sugar template, which led to an increased mechanical deformation range. The sugar template enhanced the surface roughness of the polymer, resulting in an improvement in the adhesion of nanomaterials to the polymer surface. Subsequently, it was functionalized by coating with hybrid nanomaterials of 1D silver nanowires (AgNWs) and 2D reduced graphene oxide (rGO) through a dip-coating process. When pressure is applied, the rGO/AgNWs/ecoflex pressure sensor deforms along the direction of the applied force, causing the conductive multidimensional nanomaterials to come into contact. Consequently, the improved networks between the two nanomaterials expanded the current paths, increasing the current detected through the electrodes attached to the sensor. The rGO/AgNWs/ecoflex pressure sensor, with its porous structure within the flexible ecoflex, demonstrated a high sensitivity (up to 2.29 kPa-1) over a wide detection range of 0-120 kPa. This enables the monitoring of a wide range of motions, including small pressures such as subtle touch, respiratory vibrations, and drinking, as well as large pressures such as human bodily movements, finger/arm bending, and foot pressure, making it an excellent candidate for applications requiring precise pressure detection.

Rapid In Situ Preparation of Conductive Graphite-like Films on Polymer Surfaces via Hydrogen Plasma Technology.

Many special polymer materials with high strength, low density, and high processability have been developed for the substitution of metal products in recent years; however, their electrical insulation properties sometimes limit their application in medicine, electronics, and aerospace fields. Constructing a conductive layer on polymers may be a promising strategy for conquering these problems, but simply obtaining a high-quality conductive layer remains a challenge. Here, we develop a universal strategy to in situ fabricate a conductive graphite-like film on various polymer surfaces based on a simple one-step gas plasma ion implantation method. Theoretical and experimental results confirm that the reducibility of free radicals and the electrophilicity of cations in plasma are critical for the formation of graphite-like films on polymer surfaces. Compared with argon and oxygen plasma, hydrogen plasma with strong reducing hydrogen radicals and weak electrophilic hydrogen cations can produce the highest degree of graphitization of graphite-like films. The as-prepared polymers treated by hydrogen plasma ion implantation presented good surface conductivity and reduced friction coefficient, which has great potential for application in medicine, electronics, and aerospace fields.

Ice Adhesion to Cationic, Anionic, Zwitterionic, and Nonionic Polymer Surfaces

Ice Adhesion to Cationic, Anionic, Zwitterionic, and Nonionic Polymer Surfaces

Atomistic Insights into the Ionic Response and Mechanism of Antifouling Zwitterionic Polymer Brushes.

Zwitterionic polymer brushes are not a practical choice since their ionic response mechanisms are unclear, despite their great potential for surface antifouling modification. Therefore, atomic force microscopy and molecular dynamics simulations investigated the ionic response of the surface electrical properties, hydration properties, and protein adhesion of three types of zwitterionic brushes. The surface of PMPC (poly(2-methacryloyloxyethyl phosphorylcholine)) and PSBMA (poly(sulfobetaine methacrylate)) zwitterionic polymer brushes in salt solution exhibits a significant accumulation of cations, which results in a positive shift in the surface potential. In contrast, the surface of PSBMA polymer brushes demonstrates no notable change in potential. Furthermore, divalent Ca2+ enhances protein adhesion to polymer brushes by Ca2+ bridges. Conversely, monovalent Na+ diminishes the number of salt bridges between PSBMA and PCBMA (poly(carboxybetaine methacrylate)) zwitterionic polymer brushes and proteins via a competitive adsorption mechanism, thereby reducing protein adhesion. A summary of polymer brush material selection and design concepts in a salt solution environment is provided based on the salt response law of protein adhesion resistance of various zwitterionic materials. This work closes a research gap on the response mechanism of zwitterionic polymer brushes' antifouling performance in a salt solution environment, significantly advancing the practical use of these brushes.

Highly Resistive Biomembranes Coupled to Organic Transistors enable Ion‐Channel Mediated Neuromorphic Synapses

AbstractOrganic electrochemical transistors (OECTs) functionalized with lipid membranes could enable new hybrid synapses for sensing and neuromorphic computing in biological media. However, prior attempts to pair these components resulted in low quality membranes formed on the OECT surface. We present a new method for forming a highly‐resistive phospholipid bilayer coupled to a poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) OECT that avoids the disruptive effects of the rough polymer surface. Transistor coupled droplet bilayers (TCDBs) formed from diphytanoyl phosphatidylcholine lipids exhibit an average specific resistance that is 1000X higher than values reported for solid‐supported lipid membranes assembled on PEDOT:PSS. High membrane resistance and the addition of voltage‐activated ionophores enable us to demonstrate that selective ion transport and spontaneous membrane resealing in response to dynamic gate voltage imparts selective programming and memory‐storage capability to an OECT without chemical modification of the PEDOT:PSS. These capabilities enable paired‐pulse facilitation and depression with writing speeds and memory retentions that are both &gt;10X higher than previously reported with membrane‐coated OECTs. The high resistance of the TCDB establishes a basis for hybrid biomolecular synapses that can integrate stimuli‐responsive membranes and organic electronics for future applications in sensing, signal processing, and neuromorphic computing at the edge of biology.

Surface metamorphosis techniques for sustainable polymers: Optimizing material performance and environmental impact

The transition to sustainable polymers is crucial for reducing the environmental footprint of additive manufacturing, particularly in fused deposition modeling (FDM). This study investigates surface metamorphosis techniques—methods to modify polymer surfaces at micro and nanoscale levels to enhance performance and minimize environmental impact. We explore plasma treatment, chemical etching, and laser texturing on biodegradable and recycled polymers, assessing their effects on surface properties, such as adhesion, roughness, and chemical resistance. Our results demonstrate significant enhancements in mechanical properties. For example, PLA’s tensile strength increased from 55.3 MPa (untreated) to 63.8 MPa (plasma treated), and its elongation improved from 4.2% to 5.1%. PHA showed a similar trend, with tensile strength rising from 45.1 MPa to 52.6 MPa, and elongation increasing from 5.6% to 6.4%. rPET and rPP also exhibited improvements, indicating the effectiveness of these surface treatments. Employing a multi-criteria decision-making approach, we assess and prioritize these techniques based on their mechanical enhancements and sustainability profiles. While this study presents hypothetical results, it establishes a comprehensive framework for optimizing surface metamorphosis processes, guiding future experimental research. Our findings suggest that tailored surface modifications can significantly improve the performance and environmental sustainability of polymers in FDM, offering pathways for integrating eco-friendly materials into advanced manufacturing. This work contributes to the development of green manufacturing technologies by highlighting surface metamorphosis as a key strategy for achieving high-performance and sustainable materials.

Near-Surface Reconfiguration of Biopolymer Blends by Mechanical Embossment: Creation of Friction-Reduced Foils

Biopolymer blends of polylactic acid (PLA) and polybutylene adipate-co-terephthalate (PBAT) are extruded into flexible monolayer films. These blends are excellent candidates for the realization of environmentally friendly packaging applications. A necessary pre-requisite for that are appropriate tribological properties under mechanical contact. Reasonable wear resistance allows good protection of packed goods, and low friction forces reduce difficulties in stacking. In this research, mechanical embossment under high loads at room temperature was used for the modification of polymer surfaces to exhibit a significant friction reduction under dry conditions. The results particularly show a systematic decrease in the coefficient of friction for biopolymer blends containing 30 wt% and 40 wt% PBAT. FTIR was used to analyze the change in surface composition after mechanical embossing. A sophisticated FTIR calibration method revealed that the blend with 30 wt% PBAT shows a modified distribution of PBAT and PLA at the surface due to mechanical embossment. This leads to a controlled and long-lasting modification of the surface properties without a substantial change in the chemical composition of the polymer in bulk. Without the use of additional coatings, biodegradable packaging foils with improved characteristics are accessible.

Effect of Surface Polymeric Organosilicon Nanolayers on the Electrochemical and Corrosion Behavior of Copper.

The formation of polymeric self-organizing organosilicon surface nanolayers on copper occuring as a result of modification of the metal surface with organosilane-based formulations has been studied. The anticorrosive effect of such surface layers in corrosive chloride-containing electrolytes as well as in artificial and natural atmospheres has been studied in detail. It has been found that the maximum protective effect is observed at a thickness of 3.8 molecular layers, where the densest cross-linked polymer layers are formed that hinder the adsorption of chloride ions and other corrosive agents on the metal surface, thus significantly reducing the rate of their reactions with the surface copper atoms, and, as a result, inhibiting the corrosion and local anodic dissolution of the metal.