Hydrophilic Glass Research Articles

Effects of structure and material of polluted insulators on the wetting characteristics

Umbrella-type structure, the material of insulators and surface positions influence the wetting process of polluted insulator surfaces tremendously. Using a custom-made phase-angle-difference (PAD) detection device, the PAD of the different positions of different polluted insulators is measured, and the PAD curves and partial pollution surface electrical conductivity γ 20 varying with time are plotted. The results show that there is a certain difference in the wetting characteristics of different positions. The saturated wetting time of different positions of LXAY-70 insulators is 12.5-15 min; that for LXHY5-70 insulators is 12-25 min; that for XWP2-70 insulators is 8-14 min; and that for FXBW-10/70 insulators is 18-26.5 min. The umbrella-type structure is shown to have a direct effect on the wetting process of polluted insulators. The complicated umbrella-type structure, especially the existence of umbrella ribs, causes an uneven degree of wetting between the upper and lower surfaces, and leads to the increase of the difference in wetting state between the different positions. Furthermore, there is a certain difference in the wetting speed of insulators comprised of different materials. Hydrophilic porcelain and glass insulators are more easily wetted than composite insulators, even though the hydrophobicity class of composite insulators is 7.

Estimation of Size and Contact Angle of Evaporating Sessile Liquid Drops Using Texture Analysis

Size and contact angle of liquid drops are fundamental parameters in interfacial science. Accurate estimation of these parameters can provide objective information regarding several properties of the contacting surface. We leveraged principles of texture analysis to estimate the contact angle and the drop diameter from videos of evaporating sessile liquid drops deposited on solid surfaces. Specifically, we used a Harris corner detector to locate the corners and dynamically estimate the changing size and a Gabor wavelet-based approach to estimate the varying contact angle of the evaporating sessile drop. We demonstrated the ability of our approach to accurately estimate size and contact angles of drops deposited on a hydrophilic glass slide and on a paraffin film representing a hydrophobic surface. We also estimated the contact angle and size of drops deposited on horizontal and tilted surfaces to generate symmetric and asymmetric drop shapes, respectively. A software application that has the ability to analyze videos of sessile liquid drops as inputs is provided, and this tool can generate plots of the estimated contact angle and the drop diameter as a function of frame number.

Analysis of profile and morphology of colloidal deposits obtained from evaporating sessile droplets

We experimentally investigate the profile and morphology of the ring-like deposits obtained after evaporation of a sessile water droplet containing polystyrene colloidal particles on a hydrophilic glass substrate. In particular, the coupled effect of particle size and concentration are studied. The deposits were qualitatively visualized under an optical microscope and profile of the ring was measured by an optical profilometer. The profile of the ring resembles a partial torus-like shape for all cases of particles size and concentration. The cracks on the surface of the ring were found to occur only at smaller particle size and larger concentration. We plot a regime map to classify three deposit types - discontinuous monolayer ring, continuous monolayer ring, and multiple layers ring - on particles concentration - particle size plane. Our data shows a possible existence of a critical concentration (particle size) for a given particle size (concentration) at which the monolayer ring forms. For the larger particle sizes, the immersion capillary forces between the particles dominate, aiding the formation of a monolayer ring of the particles. We measure the width and height of the ring and show that they scale with particle concentration by a power law for the multiple layers ring. This scaling corroborates with an existing continuum based theoretical model. We briefly discuss the effect of the interaction of growing deposit with shrinking free surface on the ring dimensions and profile. The present results aid understanding of the ring formation process and will be useful in guiding the design of self-assemblies of the colloidal particles formed by the evaporating droplets.

Gripping ease in southern green stink bugsNezara viridulaL. (Heteroptera: Pentatomidae): Coping with geometry, orientation and surface wettability of substrate

AbstractThe southern green stink bugNezara viridulaL. (Heteroptera, Pentatomidae) is highly polyphagous, preferring apically situated seeds and fruits on more than 150 plant species belonging to over 30 plant families all over the world. This forces them to move over highly variable terrains, including plant stems, leaves, pods and buds, which requires efficient attachment. Stink bugs have long slender legs and feet (tarsi) equipped with paired curved claws, paired soft adhesive pads (pulvilli), and flattened lanceolate hairs (setae), which arise ventrally on the first and second foot segments (tarsomeres). To characterize their attachment abilities on well‐defined test substrates, here we comparatively measured and analyzed the traction forces of bugs walking horizontally and vertically on hydrophilic (water attractive) and hydrophobic (water repellent) glass plates and rods. The latter correspond to the geometry of preferred feeding sites of stink bugs in the field. The results show a clear contribution of tarsal flattened lanceolate hairs to the stink bug's attachment. Higher traction forces are generated on a glass rod than on a glass plate, corresponding to up to individual maximum of 43 times the stink bug's body weight. Substrate hydrophobicity promotes the attachment, while the measured forces are up to eight times lower when tarsal hairs are disabled. The combination of smooth and hairy tarsal pads results in a remarkable attachment ability, which enablesN. viridulato climb unstable apical plant parts, and supports their invasive behavior and global dispersion.

Alternate Soaking Technique for Micropatterning Alginate Hydrogels on Wettability-patterned Substrates.

Techniques for patterning hydrogels are important for fabrication of cell culture, analytical, and actuator devices at the micro- and nanometer length scales. In this study, we fabricated alginate hydrogels cross-linked by divalent cations on wettability-patterned substrates by alternate soaking of precursor solutions of sodium alginate and divalent cations. The wettability-patterned substrates were fabricated on hydrophilic glass plates modified with hydrophobic self-assembled monolayers of hexamethyldisilazane followed by exposure to an ultraviolet/ozone atmosphere through a metal mask. The film thickness of alginate gels with a width and length of 0.1 and 4 mm were tuned stepwise from 30 nm to 200 nm by adjusting the precursor conditions, including the pH, type of divalent metal ions, and sodium alginate concentration, and the alternate soaking conditions, including the dipping/withdrawal speed and number of alternate soaking cycles. This technique can be applied to other functional gels and will contribute to fabrication of hydrogel devices at the micro- and nanometer scales in the future.

Reconfigurable and Permanent Wetting Patterns on Polymer Surfaces Obtained Using Plasma Oxidation and Laser Ablation

Abstract Smart surfaces with preferably reconfigurable wetting properties can lead to key applications in labon- a-chip analytical and preparative systems. In this paper, we present our recent results obtained using polymer surfaces whose wetting properties are modified in a permanent manner using laser ablation and in a reconfigurable manner using plasma oxidation. Polydimethylsiloxane (PDMS) diluted in solvent is used as the polymeric material coated over microscope glass slides in our studies. In the first part, the tracks of ~ 70 μm width are defined over the surface by surface oxidation using cold plasma exposure through a microfluidic channel. In the second part, femtosecond laser micromachining is used for selective removal of polymer coating and uncovering the hydrophilic glass substrate. We experimentally demonstrate guiding of water in the form of filaments and droplets over the obtained hydrophilic tracks of ~ 110 μm. We also discuss preliminary experiments to coat light sensitive azobenzene over a glass substrate with the help of a silane in order to achieve reversible isomerization upon periodic exposure to UV/vis radiation. Furthermore, we elaborate advantages, challenges and the significant role of such patterned surfaces in future applications.

Oil-water flow regimes in 4-mm borosilicate glass and fluorinated ethylene propylene channels: Effects of wall wettability

Formation water, found in oil deposits, is highly corrosive. By utilizing flow phenomena and surface tension forces in smaller channels (e.g., Eötvös number less than one), these fluids can be separated, thus altering corrosion and the pressure required for transport. This research investigates the effects of wall wettability on oil-water flow regimes and pressure drops. Oil-water flows were studied in 3.5-mm hydrophilic borosilicate glass and 4.0-mm hydrophobic fluorinated ethylene propylene (FEP) channels using Parol 100 mineral oil (i.e., density of 840 kg/m3 and viscosity of 0.0208 Pa s) and tap water (i.e., 997 kg/m3 and a viscosity of 0.001 Pa s). For these oil-water combinations, glass was water wetting (i.e., contact angle of 67° for a water droplet submerged in oil on glass) and FEP was water repelling (i.e., contact angle of 93° for a water droplet submerged in oil on FEP) under static conditions. Flow regimes and pressure drops were recorded for a range of oil superficial velocities [i.e., 0.31–3.7 m/s (glass) and 0.23–2.7 m/s (FEP)] and water superficial velocities [i.e., 0.080m/s–5.5 m/s (glass) and 0.060–5.5 m/s (FEP)]. Stratified, intermittent, annular, and dispersed flow regimes were observed in both tubes. Additional inverted and dual flow regimes were observed in the hydrophobic FEP; oil wetted the wall in inverted flows, and flow regimes occurred inside of another flow regime in dual flows (e.g., inverted-annular intermittent). The modified Weber number indicated whether the walls were wetted by oil, mixed oil and water, or water. Pressure drops were found to be correlated to the flow regime with increased pressure drops observed when oil fully or partially wetted the wall.

Inter‐ and intraspecific differences in leaf beetle attachment on rigid and compliant substrates

AbstractThe influence of substrate stiffness on the attachment ability of insects has been largely neglected so far. In the present study, traction experiments with adult beetles Gastrophysa viridula and Leptinotarsa decemlineata were carried out to study the influence of smooth, non‐structured surfaces, having different stiffness, on beetle attachment. Force measurements were performed with tethered walking adult insects, both males and females, intact and after removal of claws, on hydrophilic (normal) and hydrophobic (silanized) glass and four polydimethylsiloxane (PDMS) substrates ranging from 0.3 to 20 MPa in elastic modulus. Adult G. viridula generated higher safety factors (force/body weight) than L. decemlineata, 4.6–54.0 and 0.5–15.8 (min.–max.) respectively. The results show that the amputation of claws had no significant influence on the force generation by beetles on these smooth substrates. Males and females of both species performed best on stiffer surfaces having elastic moduli larger than 5 MPa. On the softer substrates, forces and safety factors significantly decreased. This effect was more prominent in L. decemlineata compared to the ten times lighter G. viridula. Since some natural substrates are rather soft, it is assumed that the effect of decrease in attachment ability of leaf beetles on soft substrata is of potential importance for the biology of leaf beetles.

Inkjet printing for localized coating and functionalization of medical devices

Abstract Inkjet printing has become essential for pharmaceutical research as well as biomedical applications. It is a promising tool to meet future challenges in patientindividual designed pharmaceuticals and implants. In this context, the main areas of use are high-throughput screening (HTS), drug-loaded microparticles, drug formulation and oral dose development, 3D-printing/bioprinting as well as coating of implants. This study deals with the latter. In view of promising applications for localized coating and functionalization of implant surfaces this work shows preliminary results on inkjet printing of the polymer poly(2- ethyl-2-oxazoline) (PetOx), a protein repellent polymer (PRP). To deposit single droplets with small volumes (~500 pl) of aqueous PetOx solution (50 g/l), printing parameters were determined for the piezo-driven drop-ondemand inkjet printhead NanoTip J, operating in a Nanoplotter 2.1 (both from GeSiM mbH, Germany). Different printing strategies are demonstrated by varying droplet spacing and drying time while printing on hydrophilic glass substrate. Printing and stacking of almost uniform polymer lines (width ~ 200 μm) is demonstrated.

Strong, Rebondable, Dynamic Cross-Linked Cellulose Nanocrystal Polymer Nanocomposite Adhesives.

A series of strong, rebondable polydisulfide nanocomposite adhesive films have been prepared via the oxidation of a thiol-endcapped semicrystalline oligomer with varying amounts of thiol-functionalized cellulose nanocrystals (CNC-SH). The nanocomposites are designed to have two temperature-sensitive components: (1) the melting of the semicrystalline phase at ca. 70 °C and (2) the inherent dynamic behavior of the disulfide bonds at ca. 150 °C. The utility of these adhesives was demonstrated on different bonding substrates (hydrophilic glass slides and metal), and their bonding at both 80 and 150 °C was examined. In all cases, stronger bonding was achieved at temperatures where the disulfide bonds are dynamic. For high surface energy substrates, such as hydrophilic glass or metal, the adhesive shear strength increases with CNC-SH content, with the 30 wt % CNC-SH composites exhibiting adhesive shear strengths of 50 and 23 MPa for hydrophilic glass and metal, respectively. The effects of contact pressure and time of bonding were also investigated. It was found that ca. 20-30 min bonding time was required to reach maximum adhesion, with adhesives containing higher wt % CNCs requiring longer bonding times. Furthermore, it was found that, in general, an increase in contact pressure results in an increase in the shear strength of the adhesive. The rebonding of the adhesives was demonstrated with little-to-no loss in adhesive shear strength. In addition, the 30 wt % nanocomposite adhesive was compared to some common commercially available adhesives and showed significantly stronger shear strengths when bonded to metal.

Super Stable Fluorescein Isothiocyanate Isomer I Monolayer for Total Internal Reflection Fluorescence Microscopy.

Total internal reflection fluorescence microscopy (TIRFM) is an important method in surface science and for the analysis of surface-bound macromolecules. Here, we developed and explored the use of a novel fluorescein isothiocyanate isomer I (FITC)-adsorbed monolayer for alignment and validation of TIRFM measurements and configurations. Aqueous solutions of FITC exist as several different protolytic forms (dianionic, anionic, neutral, and cationic) with each form having different emission characteristics. However, the emission behavior of FITC adsorbed on hydrophilic, hydrophobic, and unmodified glass surfaces at different pH was unknown. TIRFM imaging and spectroscopy were used to study FITC and FITC-labeled bovine serum albumin (BSA-FITC) monolayers generated on three different glass surfaces. Monolayer emission intensity, spectra, and the photobleaching profiles were all dependent on pH and the surface properties of the glass. Very strangely, however, at pH 5.0 on hydrophobic surfaces, the FITC monolayers produced were both bright and apparently unbleachable over ∼20 min of imaging (60 s total exposure). During monolayer formation at pH 5.0, we saw clear evidence for concentration-based quenching, indicating high surface coverage. When the monolayer had been rinsed with buffer to remove unbound FITC, we observed an increase in emission intensity during illumination indicative of some form of photoactivated species being present. Eventually, the fluorescence emission stabilized and remained constant for extended periods of time with no evidence of photobleaching. We hypothesize that during the adsorption process (a hydrophobic-hydrophobic interaction) there was conversion to the fluorescent quinoid form of FITC. In contrast, at pH 7.4 and 9.6 on hydrophobic surfaces, FITC monolayers had well-defined, fast photobleaching kinetics (decay to ∼50% intensity in 5-10 s). The equivalent BSA-FITC monolayers were slightly brighter, with similar photobleaching kinetics. While the precise mechanism for this unusual behavior is still unknown, all these low-cost monolayers were easily prepared, were reproducible, and can serve as convenient test samples for TIRFM alignment, calibration, and validation prior to undertaking measurements with more sensitive biogenic or biological specimens.

Role of DTAB and SDS in Bubble-Particle Attachment: AFM Force Measurement, Attachment Behaviour Visualization, and Contact Angle Study

Atomic force microscopy (AFM) and contact angle measurements were used to study the role of dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulphate (SDS) in bubble-particle attachment. The results show that the forces between bubbles and the hydrophilic glass particle were always repulsive in the absence of DTAB and SDS. An attractive hydrophobic force was induced when the particles became hydrophobic, and the force was proportional to the water contact-angle. In the presence of DTAB and SDS, the cationic head group of DTAB adsorbed onto the negative hydrophilic glass surface as a monolayer and thus induced a hydrophobic force. However, at a high DTAB concentration, the DTAB molecules began to adsorb as a bilayer, reverting back to a hydrophilic surface. The hydrophobic force disappeared and the water film between the bubble and particle was stabilised under the repulsive double-layer force. The anionic SDS molecules could not adsorb onto the hydrophilic glass surface. The repulsive force always dominated the bubble-particle interaction. In the case of hydrophobic glass, the hydrophobic force decreased, and even disappeared, with the addition of DTAB and SDS. All the findings from the AFM force curves were consistent with the attachment behaviour and contact angle results.

Pilot implantation study of a borate-glass filled hydrophilic bone cement

Hydrophilic composite-resin cements reinforced with highly degradable borate-glass may provide sustained strontium release to improve local bone quality. An 8 week pilot implantation study in a rabbit femoral defect model was conducted to evaluate the local response to new bone cement materials. The materials demonstrated favorable tissue responses with evidence of direct new bone formation. Counter to the literature, there were no beneficial effects associated with strontium releasing biomaterials. Nevertheless, highly hydrophilic glass filled cements may present benefit through rapid surface mineralization, and in vivo swelling, providing a press fit coupling to bone.

Anti-icing performance of super-wetting surfaces from icing-resistance to ice-phobic aspects: Robust hydrophobic or slippery surfaces

Ice formation and aggregation on external surfaces range from being mildly annoying to potentially life-threatening. Super-wetting surfaces are proved to display robust anti-icing properties. In this work, hydrophobic hybrid coating (HC), robust superhydrophobic fluorous coating (FC), slippery hybrid coating (SHC) and fluorous slippery coating (SFC) are successfully prepared in order to reveal the performance of super-wetting surfaces in anti-icing application from ice-resistance to ice-phobic aspects. Firstly, water crystallization point can be depressed to about −17 °C on prepared super-wetting surfaces which is 3° lower than that on hydrophilic glass surface. Water freezing time is delayed to more than 1000 s on slippery surfaces as well, which is 20-fold longer than on glass. Moreover, cyclic ice adhesion strength is significantly decreased to 0.1 N on slippery surfaces (SHC and SFC), which is 3 orders of magnitude lower than that on the other three surfaces. Frosting experiment demonstrates that SHC and SFC can suppress frost formation under low temperature and high humidity environment by effectively removing condensed water droplets, at the same time, frost formation mechanism on different surfaces is also discussed. This analysis provides insight toward designing suitable materials for anti-icing application.

Controlling the hydrophilicity and cohesion during deposition of highly oriented type I collagen films: An approach for biomedical applications

Using the Langmuir-Blodgett (LB) technology we have pioneered a straightforward and low-cost approach to fabricate highly oriented collagen in thin film format (thickness: ~20 nm, surface areas: 2.5 × ~6.0 cm). An important factor for the use of these films is their cohesion under various conditions. Film formation was studied by coating hydrophilic or hydrophobic glass substrates. The fresh or aged (2 1/2 years, −18 °C.) collagen solutions used for this purpose either contained collagen network-stabilizing agents (n-propanol or phosphate ions) or were prepared without these stabilizers. Film formation on the air/water interface was analyzed by pressure-area isotherms. Maximum surface pressures were ~4–7 mN/m and ~10–18 mN/m for isotherms using n-propanol or phosphate buffer saline (PBS), respectively, versus ~0.4–0.8 mN/m without using a stabilizer; with higher surface pressures for the combination fresh solution/n-propanol or aged solution/PBS. Deposited films were studied by optical and electron microscopy and fast Fourier transform analysis. Coatings (to both substrate types) exhibit a defined orientation of collagen aggregates within a matrix of oriented collagen when freshly made or aged collagen solutions were used and n-propanol was present during film formation. The higher degree of hydrophilicity of the aged solution does not adversely affect the cohesion and collagen orientation during film formation. Using physiological phosphate ions shows that deposition of defect-free and oriented collagen (on both substrate types) is only possible using fresh collagen solutions. Unlike n-propanol-containing solutions, films were most stable using hydrophilic glass substrates. Film formation failed in the absence of network stabilizers. Controlling the cohesion via (a) the water accessibility of collagen structures, (b) specific network stabilizers and (c) substrate properties enables tunable film characteristics for future biomedical approaches.

Biofilm formation and adhesion to bovine udder epithelium of potentially probiotic lactic acid bacteria.

Mastitis is one of the most important diseases threatening modern dairy herds. The idea of fighting the disease through colonising the udder with lactic acid bacteria (LAB), thereby building a beneficial biofilm, is the base for a probiotic approach towards mastitis control. The purpose of this study was to screen 13 LAB strains (eleven wild strains, two ATCC strains) inhibitory to the growth of mastitis-causing pathogens for their in vitro ability to form a biofilm and to adhere to bovine glandular mammary epithelium in order to assess their probiotic potential. Furthermore, we aimed to gain knowledge about the chemical nature of the adhesins involved by subjecting the bacteria to various chemical and enzymatical pre-treatments. The biofilms were grown on hydrophilic glass and on hydrophobic polypropylene in de Man, Rogosa and Sharpe (MRS) broth and afterwards quantified with a crystal violet assay. Biofilm formation was observed in all strains. However, the extent strongly depended on the strain, surface charge and medium. The adhesion assay also revealed a strong strain dependency, but this trait was also present in all of the investigated LAB isolates. Depending on the strain, chemical or enzymatical pre-treatment revealed carbohydrate molecules as well as proteins and lipids to be crucial for the adhesion of LAB to epithelial cells. The seven strains showing the strongest biofilm formation and/or adhesion represent promising candidates for further investigation in order to develop a probiotic remedy for the treatment of mastitis. Still, their safety for consumers and patients as well as their capability to colonise the udder remain to be investigated in in vivo studies.

Ultra-broadband nonlinear optical response of two-dimensional h-BN nanosheets and their hybrid gel glasses.

Hydrophilic hydroxylated hexagonal boron nitride nanosheets (BNNSs), also called 'white graphene', exhibit high water solubility, compatibility, dispersity with physical and/or chemical effects on the gel matrix, and unexpected but outstanding near-infrared adsorption and nonlinear optical limiting properties. These properties mean that hydroxylated BNNSs are suitable for practical applications in solidification and devices. Hydroxylated BNNSs are doped into an organically modified silicate matrix through a facile sol-gel process. The resulting BNNS-organically modified silicate glass hybrids demonstrate various solid structures (glass, coating, and film), good uniformity, thermostability, toughness, and high linear transmittance in the visible and near-infrared regions. Hybrid glasses showed large optical limiting effects and high doping concentrations without the addition of a compatibiliser, and their limiting thresholds and concentration exceed those of the corresponding suspensions by factors of 1.3-2 and 20-130, respectively. The optical limiting performance of BNNSs is almost equal to or may exceed those of graphene oxide and graphene in solutions and doped glasses. The combined mechanisms of nonlinear absorption, refraction, and scattering are deduced. A solid organically modified silicate hybrid transparent system doped with BNNSs is a promising candidate material for optical limiters and nonlinear optical devices. This system could be an efficient solid-state optical limiter in the visible and long-wavelength near-infrared regions (532-2000 nm).

Increased Efficiency of Solar Cells Protected by Hydrophobic and Hydrophilic Anti-Reflecting Nanostructured Glasses.

We investigated the fabrication of large-area (cm2) nanostructured glasses for solar cell modules with hydrophobic and hydrophilic properties using soft lithography and colloidal lithography. Both of these techniques entail low-cost and ease of nanofabrication. We explored the use of simple 1D and 2D nanopatterns (nanowires and nanocones) and the effect of introducing disorder in the nanostructures. We observed an increase in the transmitted light for ordered nanostructures with a maximum value of 99% for wavelengths >600 nm when ordered nanocones are fabricated on the two sides of the solar glass. They produced an increment in the efficiency of the packaged solar cell with respect to the glass without nanostructures. On the one hand, the wettability properties showed that the ordering of the nanostructures improved the hydrophobicity of the solar glasses and increased their self-cleaning capacity. On the other hand, the disordered nanostructures improved the hydrophilic properties of solar glasses, increasing their anti-fogging capacity. The results show that by selecting the appropriate nanopattern, the wettability properties (hydrophobic or hydrophilic) can be easily improved without decreasing the efficiency of the solar cell underneath.

Omniphobic membranes for direct contact membrane distillation: Effective deposition of zinc oxide nanoparticles

An omniphobic membrane was fabricated for membrane distillation (MD) by effectively depositing ZnO nanoparticles on a hydrophilic glass fiber (GF) membrane using a chemical bath deposition method to create hierarchical re-entrant structures, followed by surface fluorination and the addition of a polymer coating to lower the surface energy of the membrane. The omniphobic membranes possessed a particulate membrane morphology and an extremely high fluorine concentration on the surface. The omniphobicity of the fabricated membrane was indicated by the contact angles for water and ethanol, which were as high as 152.8±1.1° and 110.3±1.9°, respectively. Compared to hydrophobic GF membranes without deposited ZnO nanoparticles, the omniphobic membrane revealed a higher wetting resistance to low surface tension feed solutions in direct membrane distillation (DCMD) experiments. The water flux was stably maintained in a 0.3mM sodium dodecyl sulfate (SDS) solution (60°C 1M NaCl) with salt rejection rate higher than 99.99%. The results suggest that the omniphobic membrane exhibited not only superior wetting resistance to low surface tension liquids but also promise for desalinating low surface tension wastewaters.

Two-dimensional Arrays of Molecular Rods as a Precursor of Gel Fibrils

The monolayer behavior of a chiral gelator with perfluoroalkyl chains, (1R,2R)- or (1S,2S)- N,N’-diperfluoroheptanoyl 1,2-diaminocyclohexane (denoted as RR- or SS-CF7, respectively), was investigated by means of the Langmuir-Blodgett method. The AFM image of an enantiomeric film deposited onto a hydrophilic glass plate exhibited an array of rod-like aggregates with 0.05-0.8 μm in diameter, suggesting that they were a two-dimensional analogue of fibrils in a gel.