Solvent-structured PEDOT:PSS surfaces: fabrication strategies and nanoscale properties

We present the preparation of nanostructured conducting PEDOT:PSS thin films by solvent vapor annealing (SVA), using the low boiling point solvent tetrahydrofuran (THF). An Atomic Force Microscopy (AFM) study allowed the observation of distinct nanostructure development as a function of solvent exposure time. Moreover, the nanostructures’ physical properties were evaluated by nanomechanical, nanoelectrical, and nano-FTIR measurements. In this way, we were able to differentiate the local response of the developed phases and to identify their chemical nature. The combination of these techniques allowed to demonstrate that exposure to THF is a facile method to effectively and selectively modify the surface nanostructure of PEDOT:PSS, and thereafter its final properties. Moreover, our nanoscale studies provided evidence about the molecular rearrangements that PEDOT:PSS suffers during nanostructure fabrication, a fundamental fact in order to expand the potential applications of this polymer in thermoelectric and optoelectronic devices.

Thermoplastic Forming of a Hydrophilic Surface with a Nanostructure Array on Zr-Cu-Ni-Al-Y Bulk Metallic Glass

The poor thermoplastic formability of reactive Zr-based bulk metallic glass becomes the main limiting factor for replacing the noble-metal-based and Be-rich bulk metallic glasses in nanostructure fabrication. In our work, a (Zr50.7Cu28Ni9Al12.3)98.5Y1.5 bulk metallic glass with good thermoplastic formability has been developed by alloying, where Y addition enlarges the processing window and decreases the viscous resistance of supercooled liquid caused by the high free volume density. The prepared Zr-Cu-Ni-Al-Y bulk metallic glass nanostructure retains the amorphous characteristic and generates the complex oxidization products in the surface layer. The enhanced hydrophilicity of the as-embossed surface follows a Wenzel-impregnating wetting regime, and it can be attributed to the large roughness coefficient induced by the capillary effect. This study provides a low-cost and environmentally friendly bulk metallic glass system to manufacture the nanostructure with a broad prospect in the field of electrocatalysis.

Capillary Effect Enhancement in a Plastic Capillary Tube by Nanostructured Surface

We investigated the enhancement of the capillary effect in a plastic capillary tube using only a nanostructured surface. Since plastic is a hydrophobic material, the capillary effect does not emerge without an additional coating or plasma treatment process. Therefore, capillary effect enhancement by the nanostructure fabrication method is expected to reduce the cost and minimise the contamination produced in the human body. By combining a hydrophilic nylon resin and a nanostructure at the tip of the plastic pipette, we could confirm that the capillary effect was produced solely by the tube fabrication process. The produced capillary effect increased linearly with increasing nanostructure height when a standard solution with a surface tension of 70 mN·m−1 was used. Thus, we can conclude that including the plastic part with nanostructure can be useful for biomedical applications. In addition, we suggest that the proposed method is highly effective in controlling the wetting properties of plastic surfaces, compared to the typical coating or plasma treatment processes.

Helical polymer self-assembly and chiral nanostructure formation

This review surveys recent progress towards robust chiral nanostructure fabrication techniques using synthetic helical polymers, the unique inferred properties that these materials possess, and their intricate connection to natural, biological chirality.

Nanostructure Fabrication in Oil Media for Enhanced Thermophysical Properties

Recently, researchers have focused on molten-salt-based nanofluids, relying on their unique ability to form special fractallike nanostructures due to the interaction between molten salt ionic molecules and the nanoparticles. These nanostructures are thought to be causing the observed heat capacity enhancement. Thus far, this phenomenon was believed to be exclusive to molten salt nanofluids. In this study, the nanostructure observed in molten-salt-based nanofluids is mimicked, and similar fractallike nanostructures were formed in-situ in polyalphaolefin (PAO) oil as the base fluid by dispersing alumina (Al2O3) nanoparticles (1% wt. concentration) in the PAO and adding hydroxyl-ended polymer (PPG) (1% wt. concentration) as surfactants to form “artificial” nanostructures by ionically bonding to the nanoparticle’s surface. The effect of these artificial nanostructures was studied to confirm that they affect the base fluid similar to the nanostructures formed in molten salt nanofluids. Results showed an increase of 4.86% in heat capacity, and a 42% increase in viscosity was measured at high shear rates, as well as a noticeable non-Newtonian rheological behavior at low shear rates. These results show that the nanostructure has formed and that the thermophysical and rheological properties of the oil have been affected as expected.

An Experiment-Based Profile Function for the Calculation of Damage Distribution in Bulk Silicon Induced by a Helium Focused Ion Beam Process

The helium focused ion beam (He-FIB) is widely used in the field of nanostructure fabrication due to its high resolution. Complicated forms of processing damage induced by He-FIB can be observed in substrates, and these damages have a severe impact on nanostructure processing. This study experimentally investigated the influence of the beam energy and ion dose of He-FIB on processing damage. Based on the experimental results, a prediction function for the amorphous damage profile of the single-crystalline silicon substrate caused by incident He-FIB was proposed, and a method for calculating the amorphous damage profile by inputting ion dose and beam energy was established. Based on one set of the amorphous damage profiles, the function coefficients were determined using a genetic algorithm. Experiments on single-crystalline silicon scanned by He-FIB under different process parameters were carried out to validate the model. The proposed experiment-based model can accurately predict the amorphous damage profile induced by He-FIB under a wide range of different ion doses and beam energies.