scholarly journals Single‐step deposition of hexamethyldisiloxane surface gradient coatings with a high amplitude of water contact angles over a polyethylene foil

Author(s):  
Hediyeh Malekzad ◽  
Tommaso Gallingani ◽  
Federica Barletta ◽  
Matteo Gherardi ◽  
Vittorio Colombo ◽  
...  
Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 2897
Author(s):  
Sílvia Petronilho ◽  
André Oliveira ◽  
M. Rosário Domingues ◽  
Fernando M. Nunes ◽  
Manuel A. Coimbra ◽  
...  

Starch is a promising candidate for preparing biodegradable films with useful gas barriers and thermoplastic capabilities. However, these materials are hydrophilic and brittle, thus limiting their application range. To overcome these drawbacks, it has been hypothesized that starch can be hydrophobized and plasticized during the starch-based film production using a single-step approach and following transesterification principles. In this work, KOH powder and spent frying oil (SFO) were used as an alkaline catalyst and a source for triacylglycerides, respectively, to promote the modification of starch. Different ratios of SFO (w/w related to the dried starch weight) were tested. When compared to the neat films (without a catalyst and SFO), the incorporation of at least 15% SFO/KOH gave rise to transparent, hydrophobic (water contact angles of ca. 90°), stretchable (ca. 20×), elastic (ca. 5×), and water tolerant starch-based films, contrary to the films produced without the catalyst. ATR-FTIR and 1H NMR revealed structural differences among the produced films, suggesting that starch was modified with the SFO-derived fatty acids. Therefore, adding KOH during the potato starch/spent frying oil-based film’s production was determined to be a promising in situ strategy to develop starch-based materials with improved hydrophobicity and flexibility, while valorizing the potato chip industry’s byproducts.


Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 38
Author(s):  
Faiza Safdar ◽  
Amjed Javid ◽  
Munir Ashraf

Synthesis and modification of nanoparticles to make them suitable to functionalise a substrate for various application fields involves many steps, which are complex, time-consuming, and sometimes require special equipment. This is a major drawback to meet rapid technological requirements. In this work, a procedure has been developed to modify TiO2 nanoparticles by the sol-gel method at their synthesis stage using titanium tetraisopropoxide and modifying agents including ODS and GPTMS. The prepared nanoparticle finish can be used as it is without any further processing, thus eliminating the need for extra steps required to decorate them on some substrate. The nanoparticles were characterised by SEM, EDX, FTIR, XRD, and zeta potential. The adhesion of the obtained nanoparticles was tested by applying them to a cellulosic substrate. The obtained substrate was subjected to mechanical action and adhesion efficiency was estimated on the basis of UV transmittance and antibacterial properties that showed excellent results. The hydrophobic properties of the obtained nanoparticles were assessed by measuring water contact angles, which reached 157.9°, indicating their superhydrophobic nature. The developed procedure is facile and will be suitable for the engineering of multiple surfaces.


2016 ◽  
Vol 879 ◽  
pp. 2501-2506 ◽  
Author(s):  
Núria Llorca-Isern ◽  
Ana Maria Escobar ◽  
Oriol Rius

Superhydrophobic surfaces, with extremely high water contact angles (CAs) of more than 150° are of special interest due to their various anti-adhesive and self-cleaning properties. Recent studies demonstrate that the superhydrophobicity principally results from the presence of binary structures at both the micrometre and nanometre scales together with the low-energy wax-like materials on the surfaces. Materials with similar properties, to those of the lotus leaf structure are very useful in several areas, such as the aeronautical industry and civil engineering; so many methods have been developed to mimic the lotus leaf structure. Metals are very important and irreplaceable engineered materials in many industrial fields. An alternative method for enhancing superhydrophobicity on different metals is proposed. The method proceeds by coating the metallic surface with a superhydrophobic reactive such as dodecanoic acid being a common application its use in paints with eco-friendly properties. The goal of this study is to induce direct superhydrophobicity by a single step and coating process on prepared surfaces of pure commercial aluminium 99.9 wt %, pure commercial 99.9 wt % copper and stainless steel grade 316L (UNS S31603). The chemical reaction proceeds by etching the activated surface with lauric acid in ethanol solutions.


Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1263
Author(s):  
Liyun Xu ◽  
Yu Zhang ◽  
Ying Guo ◽  
Ruiyun Zhang ◽  
Jianjun Shi ◽  
...  

In order to obtain stable superhydrophobicity, suitable hydrophobic treatment agents should be selected according to different material properties. In this paper, cotton and poly(ethylene terephthalate) (PET) fabrics were respectively coated with dodecyl methacrylate (LMA) via argon combined capacitively coupled plasma (CCP), and the surface hydrophobicity and durability of the treated cotton and polyester fabrics are also discussed. An interesting phenomenon happened, whereby the LMA-coated cotton fabric (Cotton-g-LMA) had better water repelling and mechanical durability properties than LMA-coated PET fabric (PET-g-LMA), and LMA-coated hydroxyl-grafted PET fabrics (PET fabrics were successively coated with polyethylene glycol (PEG) and LMA, PET-g-PEG & LMA) had a similar performance to cotton fabrics. The water contact angles of Cotton-g-LMA, PET-g-LMA and PET-g-PEG & LMA were 156°, 153° and 155°, respectively, and after 45 washing cycles or 1000 rubbing cycles, the corresponding water contact angles decreased to 145°, 88°, 134° and 146°, 127° and 143°, respectively. Additionally, thermoplastic polyurethane (TPU) and polyamides-6 (PA6) fabrics all exhibited the same properties as the PET fabric. Therefore, the grafting of hydroxyl can improve the hydrophobic effect of LMA coating and the binding property between LMA and fabrics effectively, without changing the wearing comfort.


Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3950
Author(s):  
Abeer Alassod ◽  
Syed Rashedul Islam ◽  
Mina Shahriari Khalaji ◽  
Rogers Tusiime ◽  
Wanzhen Huang ◽  
...  

Compositing is an interesting strategy that has always been employed to introduce or enhance desired functionalities in material systems. In this paper, sponges containing polypropylene, lignin, and octavinyl-polyhedral oligomeric silsesquioxane (OV-POSS) were successfully prepared via an easy and elegant strategy called thermally induced phase separation (TIPS). To fully explore the behaviour of different components of prepared sponges, properties were characterized by a thermogravimetric analyser (TGA), differential scanning calorimetry (DSC), Fourier transform infrared measurement (FTIR), and scanning electron microscopy (SEM). Furthermore, wettability properties toward an organic liquid and oil were investigated. The FTIR analysis confirmed the chemical modification of the components. TGA and DSC measurements revealed thermal stability was much better with an increase in OV-POSS content. OV-POSS modified sponges exhibited ultra-hydrophobicity and high oleophilicity with water contact angles of more than 125°. The SEM revealed that POSS molecules acted as a support for reduced surface roughness. Moreover, OV-POSS-based blend sponges showed higher sorption capacities compared with other blend sponges without OV-POSS. The new blend sponges demonstrated a potential for use as sorbent engineering materials in water remediation.


Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 325
Author(s):  
Nitin Chandra teja Dadi ◽  
Matúš Dohál ◽  
Veronika Medvecká ◽  
Juraj Bujdák ◽  
Kamila Koči ◽  
...  

This research was aimed at the preparation of a hybrid film based on a layered silicate saponite (Sap) with the immobilized photosensitizer phloxine B (PhB). Sap was selected because of its high cation exchange capacity, ability to exfoliate into nanolayers, and to modify different surfaces. The X-ray diffraction of the films confirmed the intercalation of both the surfactant and PhB molecules in the Sap film. The photosensitizer retained its photoactivity in the hybrid films, as shown by fluorescence spectra measurements. The water contact angles and the measurement of surface free energy demonstrated the hydrophilic nature of the hybrid films. Antimicrobial effectiveness, assessed by the photodynamic inactivation on hybrid films, was tested against a standard strain and against methicillin-resistant bacteria of Staphylococcus aureus (MRSA). One group of samples was irradiated (green LED light; 2.5 h) and compared to nonirradiated ones. S. aureus strains manifested a reduction in growth from 1-log10 to over 3-log10 compared to the control samples with Sap only, and defects in S. aureus cells were proven by scanning electron microscopy. The results proved the optimal photo-physical properties and anti-MRSA potential of this newly designed hybrid system that reflects recent progress in the modification of surfaces for various medical applications.


2020 ◽  
Vol 11 (1) ◽  
pp. 67
Author(s):  
Ján Iždinský ◽  
Ladislav Reinprecht ◽  
Ján Sedliačik ◽  
Jozef Kúdela ◽  
Viera Kučerová

The bonding of wood with assembly adhesives is crucial for manufacturing wood composites, such as solid wood panels, glulam, furniture parts, and sport and musical instruments. This work investigates 13 hardwoods—bangkirai, beech, black locust, bubinga, ipé, iroko, maçaranduba, meranti, oak, palisander, sapelli, wengé and zebrano—and analyzes the impact of their selected structural and physical characteristics (e.g., the density, cold water extract, pH value, roughness, and wettability) on the adhesion strength with the polyvinyl acetate (PVAc) adhesive Multibond SK8. The adhesion strength of the bonded hardwoods, determined by the standard EN 205, ranged in the dry state from 9.5 MPa to 17.2 MPa, from 0.6 MPa to 2.6 MPa in the wet state, and from 8.5 MPa to 19.2 MPa in the reconditioned state. The adhesion strength in the dry state of the bonded hardwoods was not influenced by their cold water extracts, pH values, or roughness parallel with the grain. On the contrary, the adhesion strength was significantly with positive tendency influenced by their higher densities, lower roughness parameters perpendicular to the grain, and lower water contact angles.


Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3816
Author(s):  
Haidong He ◽  
Risheng Hua ◽  
Xuan Li ◽  
Chunju Wang ◽  
Xuezhong Ning ◽  
...  

Laser irradiation is a popular method to produce microtextures on metal surfaces. However, the common laser-produced microtextures were hierarchical (multiscale), which may limit their applicability. In this paper, a method of two-step laser irradiation, combining first-step strong ablation and sequentially second-step gentle ablation, was presented to produce micron-rough surface with single-scale microtextures. The effect of laser fluence on the Ti–6Al–4V surface morphology and wettability were investigated in detail. The morphology results revealed that the microtextures produced using this method gradually evolved from multiscale to single-scale meanwhile from microprotrusions to microholes with increasing the second-step laser fluence from 0.0 to 2.4 J/cm2. The wettability and EDS/XPS results indicated that attributing to the rich TiO2 content and micron roughness produced by laser irradiation, all the two-step laser-irradiated surfaces exhibited superhydrophilicity. In addition, after silanization, all these superhydrophilic surfaces immediately turned to be superhydrophobic with close water contact angles of 155–162°. However, due to the absence of nanotextures, the water-rolling angle on the superhydrophobic surfaces with single-scale microtextures distinctly larger than those with multiscale ones. Finally, using the two-step laser-irradiation method and assisted with silanization, multifunctional superhydrophobic Ti–6Al–4V surfaces were achieved, including self-cleaning, guiding of the water-rolling direction and anisotropic water-rolling angles (like the rice-leaf), etc.


Nanomaterials ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 706 ◽  
Author(s):  
Chaoqun Wu ◽  
Yudan Zhou ◽  
Haitao Wang ◽  
Jianhua Hu

Zwitterionic polymers are suitable for replacing poly(ethylene glycol) (PEG) polymers because of their better antifouling properties, but zwitterionic polymers have poor mechanical properties, strong water absorption, and their homopolymers should not be used directly. To solve these problems, a reversible-addition fragmentation chain transfer (RAFT) polymerization process was used to prepare copolymers comprised of zwitterionic side chains that were attached to an ITO glass substrate using spin-casting. The presence of 4-vinylpyridine (4VP) and zwitterion chains on these polymer-coated ITO surfaces was confirmed using 1H NMR, FTIR, and GPC analyses, with successful surface functionalization confirmed using water contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) studies. Changes in water contact angles and C/O ratios (XPS) analysis demonstrated that the functionalization of these polymers with β-propiolactone resulted in hydrophilic mixed 4VP/zwitterionic polymers. Protein adsorption and cell attachment assays were used to optimize the ratio of the zwitterionic component to maximize the antifouling properties of the polymer brush surface. This work demonstrated that the antifouling surface coatings could be readily prepared using a “P4VP-modified” method, that is, the functionality of P4VP to modify the prepared zwitterionic polymer. We believe these materials are likely to be useful for the preparation of biomaterials for biosensing and diagnostic applications.


Author(s):  
Grégoire David ◽  
Laurent Heux ◽  
Stéphanie Pradeau ◽  
Nathalie Gontard ◽  
Hélène Angellier-Coussy

Abstract This paper aims at investigating the potential of vine shoots (ViSh) upcycling as fillers in novel poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV) based biocomposites. ViSh particles of around 50 µm (apparent median diameter) were obtained combining dry grinding processes, and mixed with PHBV using melt extrusion. Thermal stability and elongation at break of biocomposites were reduced with increasing contents of ViSh particles (10, 20 and 30 wt%), while Young’s modulus and water vapor permeability were increased. It was shown that a surface gas-phase esterification allowed to significantly increase the hydrophobicity of ViSh particles (increase of water contact angles from 59° to 114°), leading to a reduction of 27% in the water vapor permeability of the biocomposite filled with 30 wt% of ViSh. The overall mechanical performance was not impacted by gas-phase esterification, demonstrating that the interfacial adhesion between the virgin ViSh particles and the PHBV matrix was already good and that such filler surface treatment was not required in that case. It was concluded that ViSh particles can be interestingly used as low cost fillers in PHBV-based biocomposites to decrease the overall cost of materials.


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