Vertically aligned CNT arrays: structural integrity and surface properties

Surface analysis and mechanical behaviour mapping of vertically aligned CNT forest array through nanoindentation

It is not a simple task to measure a contact angle of a water drop on a superhydrophobic surface with sessile drop method, because a roll-off angle is very low. Usually contact angle of a water drop on a superhydrophobic surface is measured by fixing a drop with intentional defects on the surface or a needle. We examined the effects of drop size and measuring condition such as the use of a needle or defects on the static contact angle measurement on superhydrophobic surface. Results showed that the contact angles on a superhydrophobic surface remain almost constant within intrinsic measurement errors unless there is a wetting transition during the measurement. We expect that this study will provide a deeper understanding on the nature of the contact angle and convenient measurement of the contact angle on the superhydrophobic surface.

In this work, a mechanically durable anticorrosion superhydrophobic coating is developed using a nanocomposite coating solution composed of silica nanoparticles and epoxy resin. The nanocomposite coating developed was tested for its superhydrophobic behavior using goniometry; surface morphology using scanning electron microscopy and atomic force microscopy; elemental composition using energy dispersive X-ray spectroscopy; corrosion resistance using atomic force microscopy; and potentiodynamic polarization measurements. The nanocomposite coating possesses hierarchical micro/nanostructures, according to the scanning electron microscopy images, and the presence of such structures was further confirmed by the atomic force microscopy images. The developed nanocomposite coating was found to be highly superhydrophobic as well as corrosion resistant, according to the results from static contact angle measurement and potentiodynamic polarization measurement, respectively. The abrasion resistance and mechanical durability of the nanocomposite coating were studied by abrasion tests, and the mechanical properties such as reduced modulus and Berkovich hardness were evaluated with the aid of nanoindentation tests.

The surface properties and electrical behavior of carbon-based materials can be effectively modified by energetic ion irradiation. In the present study, graphene oxide (GO) and cyclic olefin copolymer foils (COC, Topas 112 and 011, respectively) were irradiated with 1 MeV Au ions using a 3 MV Tandetron accelerator at fluences of 1 × 1014, 1 × 1015, and 2.5 × 1015 cm-2. The irradiation induced systematic modifications in surface chemistry, morphology, wettability, and electrical properties. Composition changes were investigated using Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA), while surface morphology and roughness were characterized by atomic force microscopy (AFM). This revealed a clear fluence-dependent evolution of nanoscale topography. The vibrational characteristics were assessed through Raman spectroscopy, and the chemical composition of the surface layers was analyzed by X-ray photoelectron spectroscopy (XPS). The surface wettability was evaluated by static contact angle measurements, and surface free energy was determined using the Owens-Wendt-Rabel-Kaelble (OWRK) method. These measurements showed a consistent decrease in water contact angle and an increase in surface free energy with increasing ion fluence in the COC substrates, whereas GO exhibited a distinct response. Electrical characterization demonstrated a pronounced fluence-dependent decrease in sheet resistivity in polymers. The results show that 1 MeV Au ion irradiation enables systematic and fluence-dependent modification of both surface and electrical properties.

Enhance the fracture toughness of RDX-based propellant: design of mussel-activated RDX surface functionalized coating

Formation and composition of adsorbates on hydrophobic carbon surfaces from aqueous laccase-maltodextrin mixture suspension

Impact of high substrate temperature on pulsed laser deposited ZnO pillars: A technological route to investigate the structural, optical and superhydrophilic properties

Triethoxysilyl functionalized hyperbranched polsiloxysilanes at the focal (FT-HBPSs) and terminal (TT-HBPSs) positions were synthesized to investigate adsorption behavior onto a silicon wafer surface. The surface of the silicon wafer adsorbed with the HBPSs was characterized by X-ray photoelectron spectroscopy, atomic force microscopy (AFM), static and dynamic water contact angle measurements. The AFM images indicated the formation size of dot-like structures were approximately 200 nm. The presence of vinyl terminal groups of FT-HBPSs permitted conversion of the surface from a non-polar hydrocarbon to a polar hydroxylated or carboxylated structures. After the polarity was changed, the surface properties were also studied using the above surface analysis techniques. The dynamic contact angle measurement indicated that the silicon wafer surface modified by FT-HBPSs was more hydrophilic in water than TT-HBPS. This behavior can be explained by the difference of connecting points between HBPS and the silicon wafer surface.

Fabrication of oleophobic fluorocarbon film by 13.56 MHz CH2F2/Ar plasma chemical vapor deposition

Novel fluorosilicone triblock copolymers prepared by two-step RAFT polymerization: Synthesis, characterization, and surface properties

The preservation of built and cultural heritage poses numerous challenges globally, given its intrinsic value and historical significance. This study assesses the performance of two surface treatments, comprising a dispersion of functionalized silicon-based nanoparticles at a concentration of 0.1% in water. Two different variants were examined: the first being simple functionalized (NS) "T1" and the second being dehydrated functionalized (NF) "T2" nanoparticles. The application of both treatments, T1 and T2, was carried out on specimens of fired clay tile using a sponge brush in two layers, with 30 min between each layer. These treatments were compared with the application of three commercial products: a 90% siloxane-based reactive grade compound (SX), a solvent-based silicone resin active (C1), and silicone-based active and water-conveyed additives (C2). After application, the specimens were evaluated simultaneously to determine the behavior and effectiveness of the treatments in two different exposure environments (in a natural urban/industrial environment for 24 months and a controlled environment in a QUV chamber for 2000 h). The performance of the treatment was assessed through the measurement of static contact angle, capillary water absorption, and optical appearance in accordance with colorimetric and FTIR standards. It was established that the application of the T2 treatment yields comprehensive outcomes in fired clay tiles as a hydrophobic treatment, imparting advantageous properties. Urban and industrial settings significantly impact visual aesthetics, as reflected in high ΔE* values. Functionalized nanoparticles demonstrate enhanced performance even at low concentrations, making them ideal for preserving the aesthetics and structural integrity of walls and roof tiles in heritage buildings.

Hysteresis during contact angles measurement

Diblock copolymers composed of a polystyrene first block and a PEG-fluoroalkyl chain-modified polystyrene second block were synthesized by controlled atom transfer radical polymerization (ATRP), starting from the same polystyrene macroinitiator. The wettability of the polymer film surfaces was investigated by measurements of static and dynamic contact angles. An increase in advancing water contact angle was evident for all the films after immersion in water for short times (10 and 1000 s), consistent with an unusual contraphilic switch of the PEG-fluoroalkyl side chains. Such a contraphilic response also accounted for the retained wettability of the polymer films upon prolonged contact with water, without an anticipated increase in the hydrophilic character. The copolymers were then used as surface-active modifiers of elastomer poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS)-based two-layer films. The elastomeric behavior of the films was varied by using SEBS matrices with different amounts of polystyrene. Whereas the mechanical properties strictly resembled those of the nature of the SEBS matrix, the surface properties were imposed by the additive. The contraphilic switch of the PEG-fluoroalkyl side chains resulted in an exceptionally high enrichment in fluorine of the film surface after immersion in water for seven days.

Fluorination of carbon fibre sizing without mechanical or chemical loss of the fibre

A narrow process window for the preparation of polytypes of microcrystalline silicon carbide thin films by hot-wire CVD method