Superhydrophobic Surface by Replication of Laser Micromachined Pattern in Epoxy/Alumina Nanoparticle Composite

Superhydrophobic surfaces were obtained by superposition of microstructure—defined by replication of laser micromachined masters, with nanostructure—created by durable epoxy/γ-Al₂O₃ nanoparticle composite, used for replication. Hierarchical surface topography thus obtained consisted of hexagonally spaced microcavities and nanoparticle agglomerates, exposed on the replica surface by radio frequency (RF) air plasma etching. Surface topography was further enhanced by rims around the microcavity edges, resulting from nanosecond laser micromachining defects in aluminum masters. Subsequent wet chemical hydrophobization with 1H,1H,2H,2H-perfluorotetradecyltriethoxysilane (PFTDTES) provided superhydrophobic behavior in replicas with a microcavity spacing of 30 μm, as indicated by a water contact angle of 160° and a sliding angle of 8°. The preparation method is relatively simple, inexpensive, and potentially scalable.This work was supported by the National Science Centre of Poland through projects nos. 2011/03/N/ST8/05879 and UMO-2012/05/B/ST8/02876. The authors are grateful to Professor Weimin Liu and Professor Feng Zhou of the Lanzhou Institute of Chemical Physics, Chinese Academy of Science, for making the laser micromachining, JEOL SEM, and Drop Shape Analysis equipment available

Polysaccharide-based self-assembling nanohydrogels: An overview on 25-years research on pullulan

The aim of this overview is to review the evolution of the studies carried out, during more than 25 years, on nanohydrogels obtained by self-assembling of pullulan (PUL) using several hydrophobization strategies. After the first publications, mainly devoted to the preparation and characterization of PUL nanogels, a remarkable number of studies demonstrated how wide can be the field of applications within the main topic of biopharmaceutics. Numerous hydrophilic and lipophilic drugs were entrapped in the nanogel networks, consequently PUL nanogels have been proposed as delivery systems for single drugs and for combination therapies which allowed improvements of pharmacological activities and patient compliance. Furthermore, the large amount of water content allowed loading also proteins which could maintain their native structure and properties. Stimuli-sensitive and stealth PUL nanogel formulations allowed improving the performances of antitumor drugs. These nanohydrogels have also been studied for imaging techniques and for vaccines to be administered by injection and by mucosal application. The studies on PUL nanogels are still in progress and the perspectives for future researches are also addressed

Main properties of sands hydrophobized by alkoxysilane emulsions

The results of laboratory tests and geotechnical view on sands hydrophobized by alkoxysilane emulsions are presented. For the soils subjected to this process, very low permeability and no capillary elevation was observed. Laboratory tests also indicate that other physical and mechanical properties of hydrophobized sands remain nearly untouched, i.e., the considered hydrophobisation process does not reduce the strength of soils. Properly composed alkoxysilane emulsions can also solidify in pores to produce a stabilizing silicate binder. The filtration barriers in ground and soil stabilization are thus considered as possible applications of the hydrophobized soils. The process of treatment of granular soils with alkoxysilanes is neutral for the environment and the cost of implementation of the method is relatively low.http://www.degruyter.com/view/j/acgeo.2014.62.issue-5/s11600-014-0223-8/s11600-014-0223-8.xml?format=IN

Template-dependent hydrophobicity in mesoporous organosilica films

A template dependence of the degree of self-hydrophobization of methylene-bridged periodic mesoporous organosilica (PMO) films is reported. The film with the smallest pore size of 1.7 nm, templated by CTAC, results in higher hydrophilicity when compared to films with a pore size of 4.1 or 5.3 nm, templated by BrijL4 and BrijS10, respectively. Both the surface and the bulk hydrophilicity were evaluated by water contact angle measurements and water ellipsometric porosimetry and the same trends were observed. Additionally, we provide the first evidence for a steric hindrance of the self-hydrophobization process. We show that a partial template removal results in the methylene-to-methyl transformation being observed at a temperature as low as 200 degrees C, significantly lower than previously demonstrated. These results should be taken into account when PMO materials are considered for applications such as low-k dielectrics, membranes, catalyst and chromatographic supports, and drug carriers

Cellulose oxidation by Laccase-TEMPO treatments

In this work, laccase-TEMPO (Lac-T) treatments were applied to bleached commercial dissolving pulp in order to introduce carbonyl and carboxyl groups, which were found to improve dry and wet strength-related properties. Also the solubility behavior towards xanthate reactions was assessed. The effect of a refining step (R) before the oxidative treatment, the absence or presence of oxygen pressure, TEMPO dose (2 or 8% oven dried pulp) and reaction time (8 or 20 h) were thoroughly examined. Treatments conducted in the presence of oxygen pressure exhibited greater amount of functional groups. Introducing a pre-refining treatment resulted in similar functional groups but higher wet strength was achieved. Specifically, a high W/D strength ratio was observed, indicating that wet strength-related property was satisfactorily developed. Besides the fact that all Lac-T treatments caused severe cellulose degradation, no fiber strength loss was detected. In fact, all oxidized samples presented higher Wet Zero-Span Tensile Strength, mainly in R+ Lac-T (O2) sample, which suggested the formation of hemiacetal linkages between the new introduced aldehyde groups and available free hydroxyl groups resulting from fibrillationPostprint (author's final draft

Design of surface-active artificial enzyme particles to stabilize Pickering emulsions for high-performance biphasic biocatalysis

© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Surface-active artificial enzymes (SAEs) are designed and constructed by a general and novel strategy. These SAEs can simultaneously stabilize Pickering emulsions and catalyze biphasic biotransformation with superior enzymatic stability and good re-usability; for example, for the interfacial conversion of hydrophobic p-nitrophenyl butyrate into yellow water-soluble p-nitrophenolate catalyzed by esterase-mimic SAE

Novel hydrophobization of wood by epoxidized linseed oil. Part 2. Characterization by FTIR spectroscopy and SEM, and determination of mechanical properties and field test performance

Scots pine samples were impregnated with epoxidized linseed oil (ELO) by means of a two-step process, and the effect of treatments has been studied concerning the Fourier transform infrared (FTIR) spectra, mechanical properties, moisture uptake, and field test performance. FTIR analysis of ELO-treated samples revealed that part of the ELO epoxy reactive group was chemically bound to the hydroxyl groups of wood. ELO-treated samples have improved dimensional stability, while the mechanical properties were slightly reduced and the moisture uptake was significantly lowered. The field performance of lap joints treated with ELO (90 kg m(-3)) after 60 months' exposure showed great improvements in performance, as the average annual moisture content (MC) was maintained at the level of 19.3% compared to 34.6% for lap joints treated with linseed oil (LO). The lap-joint area was not stained, and less discoloration by staining fungi on the external surfaces was observed in ELO-treated samples compared to samples treated with LO

Direct Semiconductor Wafer Bonding in Non-Cleanroom Environment: Understanding the Environmental Influences on Bonding

We investigated semiconductor direct wafer bonding in a regular, non-cleanroom environment to understand environmental influences on bonding characteristics. The correlations among surface treatments, particle densities, bonding strengths, and interfacial conductivities were systematically investigated. On the basis of our investigation and condition optimization, we realized direct semiconductor bonding in the regular atmosphere with high interfacial mechanical stabilities and electrical conductivities, sufficient for device applications. Furthermore, we demonstrated fabrication and operation of solar cells using the developed bonding technique, with current paths across the bonded interfaces. These results and related technical insights may be useful for a low-cost, simpler manufacture of high-performance electrical and optical devices