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AbstractGraphene, a two-dimensional carbon nanomaterial, has garnered widespread attention across various fields due to its outstanding properties. In dental implantology, researchers are exploring the use of graphene-functionalized polymer surfaces to enhance both the osseointegration process and the long-term success of dental implants. This review consolidates evidence from in-vivo and in-vitro studies, highlighting graphene’s capacity to improve bone-to-implant contact, exhibit antibacterial properties, and enhance mechanical strength. This research investigates the effects of incorporating graphene derivatives into polymer materials on tissue response and compatibility. Among 123 search results, 14 articles meeting the predefined criteria were analyzed. The study primarily focuses on assessing the impact of GO and rGO on cellular function and stability in implants. Results indicate promising improvements in cellular function and stability with the use of GO-coated or composited implants. However, it is noted that interactions between Graphene derivatives and polymers may alter the inherent properties of the materials. Therefore, further rigorous research is deemed imperative to fully elucidate their potential in human applications. Such comprehensive understanding is essential for unlocking the extensive benefits associated with the utilization of Graphene derivatives in biomedical contexts. [ABSTRACT FROM AUTHOR]

Matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) is an essential analytical technique for the molecular characterization of biomolecules and synthetic polymers. Its ability to provide comprehensive compositional information not afforded by other techniques, with high sensitivity and selectivity, is highly influenced by the sample preparation of the material prior to analysis. This review discusses MALDI-MS sample preparation protocols that do not utilize solvents. Such methods provide alternative routes for analyzing insoluble polymeric materials and may also reveal information that is not attainable with solvent-based sample preparation techniques. Additionally, this review will present relevant surface analysis and imaging results only achievable with solvent-free sample preparation methodologies.

Materials for biomedical applications often need to be coated to enhance their performance, such as their biocompatibility, antibacterial, antioxidant, and anti-inflammatory properties, or to assist the regeneration process and influence cell adhesion. Among naturally available substances, chitosan meets the above criteria. Most synthetic polymer materials do not enable the immobilization of the chitosan film. Therefore, their surface should be altered to ensure the interaction between the surface functional groups and the amino or hydroxyl groups in the chitosan chain. Plasma treatment can provide an effective solution to this problem. This work aims to review plasma methods for surface modification of polymers for improved chitosan immobilization. The obtained surface finish is explained in view of the different mechanisms involved in treating polymers with reactive plasma species. The reviewed literature showed that researchers usually use two different approaches: direct immobilization of chitosan on the plasma-treated surface or indirect immobilization by additional chemistry and coupling agents, which are also reviewed. Although plasma treatment leads to remarkably improved surface wettability, this was not the case for chitosan-coated samples, where a wide range of wettability was reported ranging from almost superhydrophilic to hydrophobic, which may have a negative effect on the formation of chitosan-based hydrogels. [ABSTRACT FROM AUTHOR]

Biofilm formation can be slowed down by restricting protein adhesion on a surface, or by antimicrobial/biocidal activity of the material (among other methods). In this progress report, the recent work on alternatives to single component antimicrobial or protein‐repellent polymer materials is presented. These are microstructured bifunctional polymer surfaces and self‐regenerating polymer multilayer stacks. The microstructured polymer surfaces consist of antimicrobial, protein‐adhesive polymer patches, and nonfouling, protein repellent‐polymer patches. By carefully balancing the size and architecture of the adhesive and repellent patches, materials with simultaneous antimicrobial activity and strong protein repellency are obtained. At similar polymer patch sizes, protein adhesion is lower on hydrogels with a low elastic modulus than on polymer monolayers attached to stiff substrates. Surface‐regenerating polymer multilayer stacks are constructed from alternating layers of antimicrobial polymer hydrogels and degradable, soluble, or depolymerizable sacrificial layers. Top layer shedding, which imitates reptiles shedding their skin, rejuvenates the surface, and regenerates the antimicrobial function of the material. Layer shedding form such materials in solution is a competition between two thermodynamic minima, top layer reattachment and top layer removal. The outcome of each shedding event depends on the kinetics of the sacrificial layer disintegration. [ABSTRACT FROM AUTHOR]

Flexible and thin polymer surfaces with superhydrophobic characteristic have great prospects in many engineering fields, such as self‐cleaning, ice‐proofing, and drag reduction. However, the large‐scale practical applications of superhydrophobic materials are still rarely reported and generally impeded by the existing fabrication methods due to the limits of complicated procedures, toxic solvent applications, harsh conditions occasionally, high cost and low yield. Herein, an ultra‐facile one‐step debonding method to develop superhydrophobic surface based on multilayer extruded macromolecular PA/PE composite film is developed. By employing thermoplasticity and extensibility of polymer film, the pristine smooth PA/PE film could get hierarchical microscale grass‐like, block island and groove structures on its surface, forming an open air‐pockets layer, which endows the normal film with new features of superhydrophobicity, low water adhesion, self‐cleaning and ice‐proofing with inexpensive, environmentally friendly, simple, and fast fabricating strategy. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulations of melt films of poly(alkyl methacrylate)s (PAMAs) with methyl, ethyl, and n‐butyl substituents, respectively, have been performed using an all‐atom model to investigate their surface and thin film properties. The applied all‐atom force fields predict the bulk densities of PAMAs in good agreement with experiments. Moreover, predictions of the surface tensions of PMMA, PEMA, and Pn‐BMA melts are in reasonably good agreement with experiments. The density profiles and orientational‐order parameters of chain segments show atomic‐scale characteristics in the air/polymer interfacial region. In the surface region, the backbone segments of PAMAs form a well‐defined layer structure with the chain vectors oriented parallel to the surface, while the ester side‐chains strongly segregate to the surface region and show perpendicular orientation to the surface, with the most pronounced surface segregation noted for Pn‐BMA. Such surface segregations of chain segments make it difficult to apply a simple relationship between the cohesive energy density and the surface tension of polymers, for example, and should be taken into account in relating the surface/thin film characteristics to the bulk properties of polymers in general. [ABSTRACT FROM AUTHOR]

Details of the design and implementation of an open-source platform for studying the adhesion of cells attached to solid substrata are provided. The hardware is based on a laser-cut flow channel connected to a programmable syringe pump. The software automates all aspects of the flow rate profile, data acquisition and image analysis. An example of the pelagic diatom Thalassiosira rotula adhered to poly(dimethyl siloxane) surfaces is provided. The procedure described enables the shear rate to be converted to drag force for arbitrary-shaped objects, of utility to the study of many cell species, especially ones that are obviously non-spherical. It was determined that 90% of cells are removed with the application of drag forces < 3 × 10 − 12 N, and that this value is relatively independent of the incubation time on the surface. This result is important to understand how marine species interact with polymer surfaces that are used in electrical insulator applications. [ABSTRACT FROM AUTHOR]

Abstract: The possibility to impart surface properties to any polymeric substrate using a fast, reproducible, and industrially friendly procedure, without the need for surface pretreatment, is highly sought after. This is in particular true in the frame of antibacterial surfaces to hinder the threat of biofilm formation. In this study, the potential of aryl‐azide polymers for photofunctionalization and the importance of the polymer structure for an efficient grafting are demonstrated. The strategy is illustrated with a UV‐reactive hydrophilic poly(2‐oxazoline) based copolymer, which can be photografted onto any polymer substrate that contains carbon–hydrogen bonds to introduce antifouling properties. Through detailed characterization it is demonstrated that the controlled spatial distribution of the UV‐reactive aryl‐azide moieties within the poly(2‐oxazline) structure, in the form of pseudogradient copolymers, ensures higher grafting efficacy than other copolymer structures including block copolymers. Furthermore, it is found that the photografting results in a covalently bound layer, which is thermally stable and causes a significant antiadherence effect and biofilm reduction against Escherichia coli and Staphylococcus epidermidis strains while remaining noncytotoxic against mouse fibroblasts. [ABSTRACT FROM AUTHOR]

Abstract: Poly(sulfur‐co‐1,3‐diisopropenyl benzene) copolymers with varying compositions are synthesized from elemental sulfur and 1,3‐diisopropenyl benzene by melt polymerization. The resulting polymers are spin‐coated onto silicon wafers, and their thin‐film properties (thickness, surface composition, hydrophobicity, swellability, roughness, and morphology) are studied. The surface composition of the polymer films (determined by X‐ray photoelectron spectroscopy) indicates that the carbon‐containing repeat units of the polymer segregate to the air–polymer interface, so that the resulting surfaces are hydrophobic. This is in line with results from surface plasmon resonance spectroscopy measurements, which indicate that the materials are protein‐adhesive. Atomic force microscopy reveals that all materials are quite rough and show signs of microphase separation. Antimicrobial assays reveal that the materials are moderately active against Escherichia coli. [ABSTRACT FROM AUTHOR]

In this study, we investigate how a surface structure underneath a surface-attached polymer coating affects the bioactivity of the resulting material. To that end, structured surfaces were fabricated using colloidal lithography (lateral dimensions: 200 nm to 1 µm, height ~15 to 50 nm). The surface structures were further functionalized either with antimicrobial, cell-adhesive polycations or with protein-repellent polyzwitterions. The materials thus obtained were compared to non-functionalized structured surfaces and unstructured polymer monolayers. Their physical properties were studied by contact-angle measurements and atomic force microscopy (AFM). Protein adhesion was studied by surface plasmon resonance spectroscopy, and the antimicrobial activity against Escherichia coli bacteria was tested. The growth of human mucosal gingiva keratinocytes on the materials was analyzed using the Alamar blue assay, optical microscopy, and live-dead staining. The data shows that the underlying surface structure itself reduced protein adhesion and also bacterial adhesion, as evidenced by increased antimicrobial activity. It also enhanced cell adhesion to the surfaces. Particularly in combination with the adhesive polycations, the surfaces increased the cell growth compared to the unstructured reference materials. Thus, functionalizing structured surfaces with adhesive polymer could be a valuable tool for improved tissue integration.

Contact-active antimicrobial polymer surfaces bear cationic charges and kill or deactivate bacteria by interaction with the negatively charged parts of their cell envelope (lipopolysaccharides, peptidoglycan, and membrane lipids). The exact mechanism of this interaction is still under debate. While cationic antimicrobial polymer surfaces can be very useful for short-term applications, they lose their activity once they are contaminated by a sufficiently thick layer of adhering biomolecules or bacterial cell debris. This layer shields incoming bacteria from the antimicrobially active cationic surface moieties. Besides discussing antimicrobial surfaces, this feature article focuses on recent strategies that were developed to overcome the contamination problem. This includes bifunctional materials with simultaneously presented antimicrobial and protein-repellent moieties; polymer surfaces that can be switched from an antimicrobial, cell-attractive to a cell-repellent state; polymer surfaces that can be regenerated by enzyme action; degradable antimicrobial polymers; and antimicrobial polymer surfaces with removable top layers. [ABSTRACT FROM AUTHOR]

The emerging infectious diseases have created one of the major practical needs to develop active packaging materials with durable antibacterial and antiviral properties for the food industry. To meet this demand, the development of new technologies applicable to food contact surfaces is highly desired but challenging. The recent discovery of the photoactive properties of vitamin K (VK) derivatives has raised great expectations as promising candidates in functional film development due to the generation of biocidal reactive oxygen species (ROS) by these compounds. Inspired by the excellent photoactivity of one of the light-stable VK derivatives, menadione (VK 3 ), under visible daylight irradiation, we demonstrate a protocol for the fabrication of daylight-mediated biocidal packaging materials by incorporating VK 3 into a poly (ethylene-co-vinyl acetate) (EVA) matrix. The VK 3 (i.e., 1-5% w/w) incorporated EVA films successfully demonstrated the production of ROS and antibacterial and antiviral performance against Escherichia coli , Listeria innocua , and T7 bacteriophage, respectively, under daylight exposure conditions. The results revealed that the addition of a proper percentage of VK 3 significantly enhanced the ROS productivity of the films and created a novel daylight-induced microbial killing performance on the films. The biocidal functions of the films are long-lasting and rechargeable when exposed to light repeatedly, making them a viable contender for replacing currently available conventional packaging films.

The low energy muon (LEM) technique has been used to probe local changes in the dynamical spectrum of thin film polymer samples taking place as a function of the temperature and the implantation depth below the free surface. The studies have been made on samples of polydimethylsiloxane (PDMS) and polybutadiene (PB) using the transverse magnetic field (TF) configuration and diamagnetic probe muons. In PDMS evidence is found for suppression of the glass transition temperature near the surface, along with significantly modified dynamics in the near-surface region as well as at depths significantly below the surface. For PB the LEM technique reveals well-defined layers of dynamical and spatial inhomogeneity at depths of order 0.1–0.2 μ m below the free surface. These inhomogeneous regions may be assigned to nanopores produced by solvent streaming during preparation of spin-cast films. A thermal annealing procedure is shown to significantly reduce the thickness of these inhomogeneous layers. These results demonstrate that using LEM in the TF configuration provides a promising new method for studying surface-modified local dynamics of polymers that is also able to reveal nanostructured buried layers in polymer films. [ABSTRACT FROM AUTHOR]

There are a growing number of microcystin-degrading organisms that have been isolated; however, their ability to degrade these toxins in an immobilized state within water treatment plant media filters is yet to be explored in detail. Modified polymer coatings were applied to a polystyrene surface through plasma polymerization to determine if biofilm attachment of two previously characterized microcystin-degrading bacteria, LH21 and ACM-3962, were enhanced. Under the experimental conditions, LH21 formed a biofilm [as measured by the specific biofilm formation (SBF) index] on the uncoated polystyrene surface, and attachment was enhanced upon the three polymer coatings, acrylic acid, propionic acid, and allyl amine. Conversely, ACM-3962 was unable to form a biofilm on any surface. This study provides insights into methods that can be used to promote attachment of such organisms to treatment plant filter media, which can ultimately result in greater control and more predictable removal of microcystins. Finally, the methods can be used for screening organisms for their ability to attach to surfaces, a critical process for biofiltration within water treatment plant filters. [ABSTRACT FROM AUTHOR]

Contact angle hysteresis phenomena on polymer surfaces have been studied by contact angle measurements using sessile liquid droplets and captive air bubbles in conjunction with a drop shape method known as Axisymmetric Drop Shape Analysis — Profile (ADSA-P). In addition, commercially available sessile drop goniometer techniques were used. The polymer surfaces were characterized with respect to their surface structure (morphology, roughness, swelling) and surface chemistry (elemental surface composition, acid–base characteristics) by scanning electron microscopy (SEM), scanning force microscopy (SFM), ellipsometry, X-ray photoelectron spectroscopy (XPS) and streaming potential measurements. Heterogeneous polymer surfaces with controlled roughness and chemical composition were prepared by different routes using plasma etching and subsequent dip coating or grafting of polymer brushes, anodic oxidation of aluminium substrates coated with thin polymer films, deposition techniques to create regular patterned and rough fractal surfaces from core–shell particles, and block copolymers. To reveal the effects of swelling and reorientation at the solid/liquid interface contact angle hysteresis phenomena on polyimide surfaces, cellulose membranes, and thermo-responsive hydrogels have been studied. The effect of different solutes in the liquid (electrolytes, surfactants) and their impact on contact angle hysteresis were characterized for solid polymers without and with ionizable functional surface groups in aqueous electrolyte solutions of different ion concentrations and pH and for photoresist surfaces in cationic aqueous surfactant solutions. The work is an attempt toward the understanding of contact angle hysteresis phenomena on polymer surfaces aimed at the control of wettability for different applications. [ABSTRACT FROM AUTHOR]

Abstract: Cysteamine was grafted on polymer foils (poly l-lactic acid, polystyrene, low and high density polyethylenes, polyethyleneterephthalate, polytetrafluoroethylene, polyvinylfluoride and polyvinylidenefluoride) previously treated (activated) in plasma discharge. Grafting of cysteamine on polymer surface is expected to provide a new material applicable in medicine treatment. Properties of the sample surfaces change significantly before and after plasma treatment and cysteamine grafting and they were studied using various methods to characterize changes in surface chemistry, polarity, wetability, etc. Surface chemistry was studied by X-ray photoelectron spectroscopy, chemistry and polarity by electrokinetic analysis and by goniometry, roughness and morphology by atomic force microscopy. Representatives of unmodified and modified polymers were used for in vitro study of adhesion and proliferation of vascular smooth muscle cells. Plasma treatment and cysteamine grafting improve dramatically surface cytocompatibility. Electrokinetic analysis and X-ray photoelectron spectroscopy confirmed the cysteamine bonds to polymer surfaces via opposite functional groups (–SH or –NH2) depending on chemistry and polarity of polymers under study. This preferential grafting influence an adhesion and proliferation of vascular smooth muscle cells significantly. Even cytocompatibility of plasma treated polytetrafluoroethylene and subsequently grafted with cysteamine is “better” in comparison with tissue culture polystyrene. [Copyright &y& Elsevier]

Highlights: [•] Supervised learning lets LIBS identify organic traces located on polymer surfaces. [•] Classifiers capture nonlinear relationships between emissions and target nature. [•] False negative rate of 2% and false positive rate of 1% are reached. [•] Proposed approach offers better understanding than other chemometric alternatives. [Copyright &y& Elsevier]

Highlights: [•] Simple and efficient nanoimprinting technique to fabricate two-dimensional nanohole arrays on the polymer surfaces has been proposed. [•] The nanoimprinting technique based on the capillary force lithography was successfully applied to PEDOT:PSS surfaces regardless of their composition and grade. [•] The nanopatterned polymer layer refracted the incident light, thereby increasing the path lengths and hence leading to enhancement in absorption of the subsequently grown organic thin films. [ABSTRACT FROM AUTHOR]

Abstract: We report on the preparation of functional polymer surfaces with controlled topography by using the breath figures approach. The resulting surfaces prepared from a mixture of a PS-b-PAA diblock copolymer and a homopolymer (PS) exhibit pores that are mainly composed of diblock copolymer whereas the rest of the surface is formed by homopolymer. The formation of a hexagonal assembly of pores was achieved by controlling several parameters during the casting process including relative humidity, composition of the blend and polymer concentration. A selective modification of the pore inner part by using appropriate polypeptide sequences permitted the use of these surfaces as scaffolds for pattern and display of active biomolecules, as ordered templates for specific recognition processes and finally for the micropatterning of bacterial cells. [Copyright &y& Elsevier]

Abstract: X-ray photon correlation spectroscopy (XPCS) has emerged as a powerful technique for investigating slow, nanometer-scale structural dynamics in materials. This paper reviews major directions of recent XPCS research on complex fluids where significant information relevant to their rheological behavior has been obtained. The review focuses on three topics: block-copolymer phases, colloidal glasses and gels, and polymer thin-film surfaces and interfaces. The paper also discusses important anticipated developments for XPCS in the near future and describes some particularly promising directions for the technique in advancing understanding of complex-fluid rheology, including the application of XPCS to microrheology. [Copyright &y& Elsevier]

Microbial adhesion and retention on surfaces are complex phenomena, critical to the formation and development of biofilms. Recently, the focus of research has been more and more on the importance of retention of bacteria under fluctuating high shear forces in biofilm formation. The aim of the present work was to carry out a comparative study of the retention process of different bacterial and yeast species using: (1) a range of surfaces with different surface free energy properties and (2) a number of different bacterial cell physiological states. It was found for the first time that once a threshold cell number is retained on the surface, microbial retention patterns are formed following a power law, i.e., not stochastic. Our results demonstrated that the overall spatial patterns of microbial retention observed for the different substrates are similar for the all investigated cell types and that the drastic modification of the surface free energy does not affect this spatial organization. On the other hand, the microbial retention patterns appear to be significantly affected by the physiological state of the cells. Finally, the experimental retention patterns have been well simulated by a general agent-based model, confirming that the typical fractal distribution of retained cells is the result of a self-organization process. [ABSTRACT FROM AUTHOR]

Abstract: Surface crystallization of calcium sulfate dihydrate (gypsum) on a series of polymeric surfaces was studied using a quartz microbalance system. Polyelectrolyte multilayer films (positively and negatively charged surfaces) were formed on the quartz crystal microbalance (QCM) sensors utilizing a layer-by-layer spin-assembly method. The kinetics of gypsum surface crystallization was quantified in terms of the evolution of gypsum mineral scale on the different surfaces. For comparison mineral scaling was also evaluated on silica and polyamide surfaces. For surfaces of the same charge polarity (+/-), the mass density of gypsum scale was lower (PSS

The surface dynamics of amorphous and semicrystalline polymer films have been measured using helium atom scattering. Time-of-flight data were collected to resolve the elastic and inelastic scattering components in the diffuse scattering of neutral helium atoms from the surface of a thin poly(ethylene terephthalate) film. Debye-Waller attenuation was observed for both the amorphous and semicrystalline phases of the polymer by recording the decay of elastically scattered helium atoms with increasing surface temperature. Thermal attenuation measurements in the specular scattering geometry yielded perpendicular mean-square displacements of 2.7 • 10-4 Å2 K-1 and 3.1 • 10-4 Å2 K-1 for the amorphous and semicrystalline surfaces, respectively. The semicrystalline surface was consistently ∼15% softer than the amorphous across a variety of perpendicular momentum transfers. The Debye-Waller factors were also measured at off-specular angles to characterize the parallel mean-square displacements, which were found to increase by an order of magnitude over the perpendicular mean-square displacements for both surfaces. In contrast to the perpendicular motion, the semicrystalline state was ∼25% stiffer than the amor- phous phase in the surface plane. These results were uniquely ac- cessed through low-energy neutral helium atom scattering due to the highly surface-sensitive and nonperturbative nature of these interactions. The goal of tailoring the chemical and physical proper- ties of complex advanced materials requires an improved under- standing of interfacial dynamics, information that is obtainable through atomic beam scattering methods. [ABSTRACT FROM AUTHOR]

The examples of phase transitions in Langmuir-Blodgett films of polyvinylidene fluoride (PVDF) and in the surface layer of polystyrene were chosen to demonstrate the great potential of using luminescent molecular probes for studying the heterogeneity of the surfaces of solids and thin films, as well as structural transformations and phase transitions in systems of different natures. The method provides unique information on the local properties of surfaces and thin films when used in combination with other techniques. [ABSTRACT FROM AUTHOR]

Abstract: Fluorinated silane functionalized poly(vinylidene fluoride) (PVDF) is synthesized by graft polymerization of 3-trimethoxylpropyl methylacrylate with PVDF followed by coupling of fluorinated silanes. Flat membrane prepared using this functionalized PVDF has a water contact angle of 140°. Superhydrophobic PVDF membrane with a contact angle larger than 150° is prepared by the electrospinning of the fluorinated silane functionalized PVDF. The morphologies of the membranes are characterized using scanning electron microscopy. The surface composition of the membranes is analyzed using FTIR and the contact angles and water drops on the surface of the membrane are measured using video microscopy. [Copyright &y& Elsevier]

Photochromic spiropyran molecules are utilized as additives for the development of polymer surfaces whose wetting characteristics can reversibly respond to irradiation with laser beams of properly chosen photon energy. The hydrophilicity is enhanced upon UV laser irradiation due to the photo-induced isomerization of the non-polar spiropyran molecules to the polar merocyanine. The situation is reversed upon green laser irradiation. Micropatterning of the photochromic-polymer films using soft lithography or photo-polymerization techniques affects their wettability towards a more hydrophobic or more hydrophilic behavior depending on the dimensions of the patterned features and on the hydrophilicity/hydrophobicity of the flat surface. The light-induced wettability variations of the structured surfaces are enhanced by up to a factor of three as compared to those on the flat surfaces. This enhancement is attributed to the photo-induced reversible volume changes to the imprinted gratings, which additionally contribute to the wettability changes due to the light-induced photochromic interconversions. [ABSTRACT FROM AUTHOR]

Adhesion interaction of the most widely distributed species of microscopic fungi: Aspergillus niger, Trichoderma viride, Penicillium funiculosum, Aspergillus terreus to surfaces of materials (polymers, metals) is studied. The force of adhesion interaction was measured by the method of centrifugal detachment. Based on the analysis of kinetic curves the macroscopic characteristics of adhesion micro-organism-metal surface were obtained. We show on the example of Aspergillus niger that stochastic nature of adhesion of microorganisms cells is caused by heterogeneity of support surface, heterogeneity of conidium sizes, and their distribution by forces of adhesion obeys the Gauss law. We established that structure of cellular wall of microscopic fungi was changed in dependence on age, and change of force of adhesion interaction correlated with changes in cellular wall structure of microscopic fungi, and dominating role in strengthening of adhesion interaction was played by increase of albuminous components concentration in surface layer of cell. [ABSTRACT FROM AUTHOR]

Abstract: We present a technique to fabricate polymer substrates with locally structured surfaces in the nanometer scale. By ion projection direct cross-linking the surface of a stretched polymer is locally cross-linked and afterwards annealed above the glass transition temperature to induce surface rippling. The rippling periodicity depends on the thickness of the cross-linked surface layer, formed through hydrogen vacancies, which are generated by the ion bombardment. We systematically studied the effect of the projectile mass on the hydrogen vacancy distribution in polystyrene (PS) samples. Simulations revealed a decreasing depth of the maximum hydrogen vacancy numbers by increasing projectile mass. This value can be correlated to the thickness of the cross-linked PS layer, which directly determines the ripple periodicity. An additional Au capping layer was used to further reduce the cross-linked layer thickness to a few nanometers. By this, defined structures with a ripple periodicity of 250nm were fabricated. In addition, the technique allows inferring the Young’s modulus of thin cross-linked PS layers. [Copyright &y& Elsevier]

Young's equation describes the wetting phenomenon in terms of the contact angle between a liquid and a solid surface. However, the contact angle is not the only parameter that defines liquid–solid interactions, an additional parameter related to the adhesion between the liquid drop and the solid surface is also of importance in cases where liquid sliding is involved. It is postulated that wetting which is related to the contact angle, and interfacial adhesion, which is related to the sliding angle, are interdependent phenomena and have to be considered simultaneously. A variety of models that relate the sliding angle to the forces developed along the contact periphery between a liquid drop and a solid surface have been proposed in the literature. Here, a modified model is proposed that quantifies the drop-sliding phenomenon, based also on the interfacial adhesion that develops across the contact area of the liquid/solid interface. Consequently, an interfacial adhesion strength parameter can be defined depending on the mass of the drop, the contact angle and the sliding angle. To verify the proposed approach the adhesion strength parameter has been calculated, based on experimental results, for a number of polymer surfaces and has been correlated with their composition and structure. The interaction strength parameter can be calculated for any smooth surface from measurements of the contact and the sliding angles. [ABSTRACT FROM AUTHOR]

Abstract: We tested a possibility of surface modification of a polytetrafluoroethylene (PTFE) film by irradiating either proton or helium ion beams for up to 20 min with both beam energies from 9 MeV to 50 MeV and beam currents from 1 nA to 100 nA. The treated PTFE films were evaluated by dynamic water contact angle measurement, scanning electron microscopy, X-photoelectron microscopy and cellular adhesion. The results indicated that lower energy and helium ion beams induced better surface modification than proton beams did, judged by the above chemical and physical changes of the films. [Copyright &y& Elsevier]