Suppression of Hydrophobic Recovery in Photo-Initiated Chemical Vapor Deposition

Photo-initiated chemical vapor deposition (PICVD) functionalizes carbon nanotube (CNT)-enhanced porous substrates with a highly polar polymeric nanometric film, rendering them super-hydrophilic. Despite its ability to generate fully wettable surfaces at low temperatures and atmospheric pressure, PICVD coatings normally undergo hydrophobic recovery. This is a process by which a percentage of oxygenated functional group diffuse/re-arrange from the top layer of the deposited film towards the bulk of the substrate, taking the induced hydrophilic property of the material with them. Thus, hydrophilicity decreases over time. To address this, a vertical chemical gradient (VCG) can be deposited onto the CNT-substrate. The VCG consists of a first, thicker highly cross-linked layer followed by a second, thinner highly functionalized layer. In this article, we show, through water contact angle and XPS measurements, that the increased cross-linking density of the first layer can reduce the mobility of polar functional groups, forcing them to remain at the topmost layer of the PICVD coating and to suppress hydrophobic recovery. We show that employing a bi-layer VCG suppresses hydrophobic recovery for five days and reduces its effect afterwards (contact angle stabilizes to 42 ± 1° instead of 125 ± 3°).

Data decoding of integer orbital angular momentum beams based in straight edge diffraction nanometric film

The orbital angular momentum revolutionized optical communications, like an OAM beam of light need not be interrupted for the transfer ofdata, provides immunity to electromagnetic interference, allows increase bandwidth, rate and transmission capacity information, making theprocess more efficient. Supported by the ability to encode information on OAM modes of light, is necessary the development of a decoder thatintegrate to hardware systems, solve the problem of current techniques, which main disadvantage is to require the use of additional energysources, increasing the implementation cost, and make it less compact. The purpose of this report is towards modelling an optoelectronicdecoder system which discriminates the orbital angular momentum mode in the beam, associated with transmitted information and translates itfrom the selected transmission channel (i.e. outdoor atmosphere) to a recognizable information. Current methodology proposed for thispurpose, integrates the use of thin films of nanometric order, whose design features allows interaction with OAM beams that, can bedistinguish its topological charge.

Thermal and light-induced spin transition in a nanometric film of a new high-vacuum processable spin crossover complex

Herein, we report the identification of a novel high-vacuum processable spin-crossover complex which can be efficiently used to prepare continuous ultrathin films with retention of switchable magnetic properties.

Properties of Calix4-Lead(Pb) Films Using Langmuir-Blodgett (LB) Technique as an Application of Ion Sensor

Calixarenes are promising compounds to be used as ionophores and for molecular recognition. Their ability to form Langmuir and Langmuir-Blodgett (LB) films is of great interest in order to obtain small sensor devices which incorporate an active nanometric film. Calix[4]arene (Calix4) has been used in this work and its ability to form Langmuir films has been shown. Calix4 forms monolayers but at higher compressions tends to form multilayers. The presence of ions in the subphase, as lead chloride salt solutions, leads to some changes in the surface pressure-area (П-A) isotherms and surface potential-area (ΔV-A) isotherms. The effective dipole moments (μ) of the calixarene molecules in the uncomplexed and complexed states has been calculated from the ΔV values by using Helmholtz equation. Some characteristics of the films and mean molecular area have been deduced from the isotherms graph.

Nanometric-Size Effect upon Diffusion and Reaction in Semiconductors: Experimental and Theoretical Investigations

The use of nanometric size materials as embedded clusters, nanometric films, nanocrystalline layers and nanostructures is steadily increasing in industrial processes aiming to produce materials and devices. This is especially true in today Si-based microelectronics with transistors made of a multitude of different thin film materials (B-, As-, and P-doped Si, NiSi (Pt), poly-Si, W, TiOx, LaO, SiO2, Al, HfO2), and exhibiting a characteristic lateral size of 32-22 nm. Size reduction leads to an increasing role of surfaces and interfaces, as well as stress and nanoscale effects upon important phenomena driving fabrication processes, such as atomic diffusion, phase nucleation, phase growth, and coarsening. Consequently, nanotechnology related to Material Science requires an investigation at the nanometric (or atomic) scale of elementary physical phenomena that are well-known at the microscopic scale. This paper is focused on nanosize effects upon diffusion in Si and Si reactive diffusion. We present recent results showing that the kinetic of lattice diffusion is enhanced in semiconductor nanometric (nano) grains, while grain boundary (GB) diffusion is not changed in nanoGBs. It is also shown that diffusion in triple-junction (TJ) is several orders of magnitude faster than GB diffusion, and that its effect cannot be neglected in nanocrystalline (nc) layers made of 40 nm-wide grains. Experimental results concerning Si sub-nanometric film reaction on Ni (111) substrate are also presented and compared to theoretical results giving new prospects concerning nanosize effects on reactive diffusion at the atomic scale.