Hydrophobic Silicon Research Articles

Spirocyclic alkoxysilane synthesized from rice straw ash for preparation of eco-friendly hydrophobic silicone coatings

The purpose of this study was to use biomass silicon resources in rice straw to synthesize high value-added organosilicon products to solve the problem of low utilization of rice straw and high pollution and energy consumption in the silicon chemical industry. In this work, spirocyclic alkoxysilane was successfully synthesized by an environmentally friendly method from rice straw ash for the first time. The spirocyclic alkoxysilane yield per gram of rice straw ash can reach up to 1.9 g. Spirocyclic alkoxysilane was used to modify silicone resin coating. This coating can withstand 150 applications of friction and still maintain good hydrophobic effect. The maximum water contact angle after friction can reach 104°. This study broadens the application of rice straw. Furthermore, this research lays the foundation for the improvement of energy-saving and emission reduction process of silicon chemical industry.

Self-Organization of Di- and Triglycine Oligopeptides in Thin Films on the Hydrophilic and Hydrophobic Silicon Surface under Exposure to Organic Compounds Vapors

Self-Organization of Di- and Triglycine Oligopeptides in Thin Films on the Hydrophilic and Hydrophobic Silicon Surface under Exposure to Organic Compounds Vapors

Hydrophobic Wafer-Scale High-Reproducibility SERS Sensor Based on Silicon Nanorods Arrays Decorated with Au Nanoparticles for Pesticide Residue Detection.

High sensitivity and reproducibility are highly desirable to a SERS sensor in diverse detection applications. Moreover, it is a great challenge to determine how to promote the target molecules to be more concentrated on the hotspots of the SERS substrate by engineering a surface with switching interfacial wettability. Along these lines, wafer-scale uniformly hydrophobic silicon nanorods arrays (SiNRs) decorated with Au nanoparticles were designed as the SERS substrate. Typically, the SERS substrate was fabricated by enforcing the polystyrene (PS) sphere self-assembly, as well as the plasma etching and the magnetron sputtering techniques. Consequently, the SERS substrate was treated by soaking within a n-dodecyl mercaptan (NDM) solution at different times in order to obtain adjustable wettabilities. By leveraging the electromagnetic enhancement resulted from the Au nanostructures and enrichment effect induced by the hydrophobicity, the SERS substrate is endowed with efficient SERS capabilities. During the detection of malachite green (MG), an ultralow relative standard deviation (RSD) 4.04–6.14% is achieved and the characteristic signal of 1172 cm−1 can be detected as low as 1 ng/mL. The proposed SiNRs’ structure presents outstanding SERS activity with sensitivity and reproducibility rendering thus an ideal candidate for potential application in analytical detection fields.

Characterization of plasmatic proteins adsorption on poly(styrene sodium sulfonate) functionalized silicone surfaces

Proteins adsorption occurs spontaneously on biomaterial upon insertion within the body. The resulting protein layer influences biomaterial biocompatibility through enhanced bio-integration or, on the contrary, adverse reactions. Furthermore, upon adsorption, proteins can undergo modifications of their structure and, ultimately, their physicochemical properties and activity. Hence, the understanding of protein adsorption on implanted materials appears essential, as exemplified by silicone breast prostheses that might lead to serious health issues.Surface modifications with a bioactive polymer, poly(styrene sodium sulfonate)-polyNaSS, on a hydrophobic silicone surface that composes breast implants, have been successfully performed under UV irradiation by a radical surface polymerization. This strategy enhances cell biocompatibility and antibacterial features. Although detailed insights related to the mechanism are still scarce, polyNaSS is supposed to promote changes in the conformation and/or orientation of adsorbed plasma proteins, reducing the odd for a biofilm to form.The present work addresses more in-depth structural investigations of the adsorbed state of two plasma proteins: Bovine Serum Albumin (BSA), as a model protein, and fibronectin (FN), for its role in cell adhesion. Using Atomic force microscopy (AFM), we report that polyNaSS showed no significant impact on the BSA structure conversely to the FN one. However, imaging findings with AFM clearly outlined a change in the structural organization of FN, going from a nano fibrillar assembly with an average length of 130 nm to a globular one when the surface was grafted. Thus, it is highlighted that polyNaSS interacts specifically with FN. In addition, cell spreading assay of L929 fibroblasts on FN-coated surfaces with optical microscopy indicated no significant impact of the change in FN structure upon fibroblasts adhesion, which displayed active elongated shapes. The present features are crucial for understanding the cell adhesion mechanism induced by surface modification.

β-silicon nitride membrane with robust inorganic-organic hybrid hydrophobic surface for water-in-oil emulsion separation

Robust hydrophobic membranes are promising for effective separation of water-in-oil emulsion, which is becoming extremely critical challenge in many sectors, including oil refinery and petrochemical industries. In this paper, robust hydrophobic ceramic membrane was fabricated and successfully applied for the water-in-oil emulsion separation process. First, porous β-silicon nitride (Si3N4) membranes with unique rod-like grains and three-dimensional network structure were fabricated. The preparation procedure was optimized considering the morphological properties, porosity, permeability and mechanical characteristics. Then, the optimized membrane was converted to a hydrophobic structure with water contact angle of 136.1°. The hydrophobic modification was achieved using organosilane pyrolysis coating method, which resulted in the formation of a robust inorganic-organic hybrid hydrophobic coating layer on the membrane structure. The hydrophobic membrane was employed for the separation of water-in-oil emulsion. At a feed pressure of 1 bar, a permeate flow of 80 L/m2 h with a water rejection of 94.3% was obtained. The presented hydrophobic silicon nitride membrane in this study is promising for a range of water-in-oil emulsion separation applications, particularly in harsh conditions.

Posterior Capsule Opacification after Cataract Surgery via Implantation with Hydrophobic Acrylic Lens Compared with Silicone Intraocular Lens: A Systematic Review and Meta-Analysis.

Hydrophobic acrylic intraocular lens (IOL) is the most popular material in cataract surgery. Posterior capsule opacification (PCO) is a long-term complication of cataract surgery. It can impair vision and adversely affect the prognosis of IOL delamination. The objective of this study was to perform a systematic review and meta-analysis to provide an updated evaluation of long-term complications and visual function after implantation with hydrophobic acrylic and silicone intraocular lenses. PubMed, Embase, and Cochrane Library were searched from January 2000 until March 2021. Randomized controlled trials (RCTs) and retrospective studies were finally included. The main outcomes were PCO value and neodymium-doped yttrium aluminum garnet (Nd : YAG) capsulotomy rate. Subgroup analysis was performed to compare hydrophobic acrylic and silicone IOLs during the follow-up period. Sensitivity analysis was also performed. The meta-analysis included a total of 17 studies. When the follow-up period was considered, the results of the analysis revealed higher PCO value (Group 3: standardized mean difference (SMD), −0.59; 95% confidence interval (CI), −0.90 to −0.28) and Nd : YAG capsulotomy rate (Group 3: risk ratio (RR), 0.60; 95% CI, 0.40–0.89) for hydrophobic acrylic IOLs than silicone IOLs during a long-term (≥6 years) follow-up. In conclusion, both the PCO value and the Nd : YAG capsulotomy rates were higher in hydrophobic acrylic IOLs group than the silicone IOLs group at long-term use (more than 6 years) after implantation.

Water-pumping and purifying hydrogels driven by diurnal temperature variation

Diurnal temperature variation is an untapped energy source, although it has seldom been exploited as such. In this study, a novel system of thermo-responsive hydrogels uses diurnal temperature variation as the only power source to pump and purify water. Water is pumped at night and released during the day using an anisotropic xylem-mimetic structure whose composite phase functions as a water channel valve. The water-pumping efficiency ranges from 78% to 92%, and the weights of the pumped water per cycle are 2–3 times larger than those of the pumping materials. The anisotropic structure and the hydrophobic silicone phase are critical in determining pumping efficiency, which allow irreversible water flow upon temperature variation. Seasonal and regional temperature changes can be matched using thermo-responsive hydrogels with different volume transition temperatures. Purification of dye-contaminated water and separation of oil–water mixtures are also successfully achieved based on the hydrophilic and the pollutant-adsorbing nature of hydrogels. Since temperature changes even faster than the diurnal temperature cycle can also power this water pumping and purification system, this novel mechanism could provide a new operational solution for future water management.

Organic/silicon nanowires hybrid solar cells using isobutyltriethoxysilane incorporated poly(3,4‐ethylenedioxythiophene):poly (styrenesulfonate) as hole transport layer

AbstractHybrid heterojunction solar cells (HHSCs) using c‐Si nanowires (SiNWs) as the absorber and poly(3,4‐ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS) as the hole selective transport layer (HTL) have been drawing more and more attention due to low cost process as well as high power conversion efficiencies (PCE). However, strong hygroscopicity of the PEDOT:PSS film causes serious degradation of the HHSCs. To improve the stability of the HHSCs, a kind of silane impregnating agent, isobutyltriethoxysilane (IBTEO), was selected as the additive to be added in the PEDOT:PSS solution. The hydrophobicity of the PEDOT:PSS film is much improved by formation of the hydrophobic silicone. The contact area between PEDOT:PSS and SiNWs is dramatically enlarged and more stable Si‐O‐Si bonds were formed at the PEDOT:PSS/SiNWs interface. As a result, the performance and stability of the HHSCs have been significantly improved. A PCE of 18.2% and a FF of 80.5% were obtained for a champion full solution processed PEDOT:PSS/SiNWs HHSC with 1 vol% IBTEO addition. The PCE remains 78% of the initial value after exposed 300 h in the air for the sample with IBTEO added in the PEDOT:PSS solution, while only 7% left for the control device without IBTEO addition.

Evaluating the Impact of Hydrophobic Silicon Dioxide in the Interfacial Properties of Lung Surfactant Films

The interaction of hydrophobic silicon dioxide particles (fumed silicon dioxide), as model air pollutants, and Langmuir monolayers of a porcine lung surfactant extract has been studied in order to try to shed light on the physicochemical bases underlying the potential adverse effects associated with pollutant inhalation. The surface pressure–area isotherms of lung surfactant (LS) films including increasing amounts of particles revealed that particle incorporation into LS monolayers modifies the organization of the molecules at the water/vapor interface, which alters the mechanical resistance of the interfacial films, hindering the ability of LS layers for reducing the surface tension, and reestablishing the interface upon compression. This influences the normal physiological function of LS as is inferred from the analysis of the response of the Langmuir films upon the incorporation of particles against harmonic changes of the interfacial area (successive compression–expansion cycles). These experiments evidenced that particles alter the relaxation mechanisms of LS films, which may be correlated to a modification of the transport of material within the interface and between the interface and the adjacent fluid during the respiratory cycle.

Evaluating the Impact of Hydrophobic Silicon Dioxide in the Interfacial Properties of Lung Surfactant Films

Evaluating the Impact of Hydrophobic Silicon Dioxide in the Interfacial Properties of Lung Surfactant Films

TRIBOLOGICAL CHARACTERISTICS OF ANTIFRICTION COMPOSITES OF POLYAMIDE AND ULTRA-HIGH MOLECULAR WEIGHT POLYETHYLENE

Analysis of current trends in improving the designs of tribo-couplings of agricultural machinery has shown that the use of polyamide 6 as an antifriction material is limited by its low moisture resistance, which leads to a significant deterioration in its elastic-strength and tribological characteristics during moisture saturation. The paper shows the possibility of using ultra-high molecular weight polyethylene as its analogue, which allows increasing the durability of tribo- couplings of hydraulic systems of agricultural machinery. (Research purpose) The research purpose is in to study the processes of friction and wear of polyamide PA 6 composites and ultra-high molecular weight polyethylene nanocomposites with obtaining dependencies linking tribological characteristics (friction coefficient and wear intensity) with operational factors (temperature, sliding speed and contact pressure). (Materials and methods). Polyamide PA 6 of the 210/310 brand was used in the work; composite of the UPA 6-15A brand, consisting of 85 percent polyamide PA 6 and 15 percent fibrous carbon filler; ultrahigh molecular weight polyethylene of the GUR 4120 brand; Tuballmatrixbeta concentrate of activated carbon nanotubes; hydrophobic nanocrystalline silicon dioxide with a dispersion of 20 nanometers, Nafen grade aluminum oxide nanofiber with a dispersion of 10- 20 nanometers. Samples were made to study the elastic-strength and tribological characteristics of composites by thermal pressing on a Gibitre hydraulic press. Samples were tested on the UAI-7000 M bursting machine and the Haake MARS III rheometer. (Results and discussion) The values of the intensity of linear wear and the dependence of the friction coefficients of composites on the sliding speed, contact pressure and temperature of industrial oil I-20A were determined for the conditions of dry friction and friction with lubrication. (Conclusions) The research results have shown that the use of ultrahigh molecular weight polyethylene and nanocomposites based on it as commercial antifriction materials of tribo- couplings is promising and requires further study.

Performance Enhancement of Self-Cleaning Hydrophobic Nanocoated Photovoltaic Panels in a Dusty Environment

The efficiency of a photovoltaic (PV) panels drops significantly in dusty environments. The variation in temperature could have a substantial impact on PV panel cells, which could further lead to high deterioration and eventually permanent damage to the PV material in the presence of dust. To resolve this issue, in this work a novel hydrophobic silicon dioxide (SiO2)-based nanoparticle coating is proposed for the PV panel, to shrink the surface stress developed between the water and the coated facet. Two identical PV modules were installed to conduct comparable experimental tests simultaneously. The first module is coated by the SiO2 nanoparticles, and the second is uncoated and used as a reference. To maintain coherency, the experiments are done in the same environmental conditions, cleaning the PV modules at regular intervals. Results reveal that the accumulated energy generated during this period of study was comprehensively enhanced. Moreover, the self-cleaning property of the hydrophobic surface of the coated panel allowed water droplets to slide smoothly down the PV module surface, carrying dust particles. Useful recommendations are made at the end to enhance the performance of PV panels in dusty environments.

Antibacterial fabric with contradictory functions of water repellency and absorbency realized by electrophoretic deposition of hydrophobic SiO2 and hydrophilic ZnO nanoparticles

Clothing and fabrics used in household and industrial applications can cause human-to-human cross-infection by residual bacteria attached to their surfaces. In particular, for fabrics used in the medical and healthcare sectors, it is vital to use highly antibacterial fabrics to prevent secondary infections caused by body fluids. In this work, antibacterial fabrics with strong water repellency were developed by electrophoretic deposition (EPD) of zinc oxide (ZnO) and hydrophobic silicon dioxide (SiO2) nanoparticles. The top layer of hydrophobic SiO2 nanoparticles prevents direct adhesion of bacterial droplets, while the bottom layer of hydrophilic ZnO nanoparticles provides antibacterial properties against the residual bacteria on the fabric. As a result, the developed fabrics can simultaneously reduce droplet adhesion and bacteria viability, effectively lowering the risk of bacterial infection. The ability to express these opposing wettabilities can be achieved by our EPD process, which can deposit various nanoparticles in porous form using electric fields on a non-conductive substrate. We expect that the fabrics developed in this work can be applied to various fields that require both antibacterial and antiwetting properties.

Durable superhydrophobic and photocatalytic cotton modified by PDMS with TiO2 supported bamboo charcoal nanocomposites

A durable superhydrophobic photocatalytic cotton fabric was prepared by titanium composite bamboo charcoal (BC) and polydimethylsiloxane (PDMS). Through comparative experiments, the TiO2-BC composite particles proved to significantly improve the hydrophobic finishing effect of PDMS. The contact angle of cotton modified with TiO2-BC/PDMS reaches 155 °. The results show that the consumption of TiO2 particles achieves a reduction of 87.5 %, without affecting the hydrophobic effect. Scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR) were employed to determine the surface physical morphology and chemical properties of the cotton fabrics correspondingly. Based on the results showed in the experiment, it was confirmed that on the one hand, the increased fiber roughness plays an important role in providing a superhydrophobic surface of cotton fabric. On the other hand, the methyl (CH3) and siloxane (SiOSi) in PDMS provided for water repellency. Furthermore, the CC/CH component was found to increase by 39 %, while the CO bond was dramatically reduced by 88 %. Thermogravimetric analysis (TGA) suggests that the thermal stability of the treated fabric was improved, and the thermal mass residue increased from 12 % to 16 %. A degradation of 85.12 % of Rhodamine B (RhB) was obtained when the photocatalysis experiment was performed under the visible light, while the contact angle can still reach above 150 ° after the test. The durability experiment proves that the TiO2-BC/PDMS modified fabric maintained a contact angle of 140 ° even after 25 times of regular soaping. Given the above, the fluorine-free hydrophobic silicone materials with porous nanocomposites develop a cost-effect and eco-friendly approach for preparing durable superhydrophobic photocatalytic textile under the circumstance of reducing chemical consumption.

Electrophilic and Nucleophilic Modifiers as a Factor of Formation of Lipophilic Properties of Surface-Modified Materials

Stabilization of the functional properties of dispersed and compact solid metals, as well as regulation of their reactivity, improvement of water-repellent, antifriction and anti-corrosion properties by creating the protective films on the surface is an urgent problem of obtaining resource-saving materials. Previously, the research conducted at REC "Nanotechnology" of Mining University proved that chemisorption of ethylhydridesiloxane vapors together with cationic surfactants based on quaternary ammonium compounds has a beneficial effect on the water-repellent properties of metals. In order to obtain the physicochemical substantiation of the effect of hydrophobization of the surface of modified dispersed metals for the first time, the study of the electrophilic-nucleophilic properties of the active substances of the surface modifiers of dispersed and compact metals was carried out using the methods of quantum-chemical modeling in HyperChem software package. The dipole moment, energy of the highest occupied and the lowest unoccupied molecular orbitals, electrophilic-nucleophilic properties were determined. The series of enhancement of nucleophilic/electrophilic properties and dipole moment for modifiers were obtained. The donor-acceptor properties, the differences in the characteristics of the molecules of alkamone (A), triamone (T) and hydrophobic silicone organic liquid were quantitatively and qualitatively established. The patterns of the formation of hydrophobic properties of the surface during the layering of molecules of ammonium and organosilicon compounds with different electrophilic-nucleophilic properties on dispersed metals have been established. Recommendations for the use of modifiers for the production of high - and superhydrophobic materials are proposed.

A Facile Method for Preparing Superhydrophobic and Flame‐Retardant Fabrics Materials

Herein, a time‐saving and green method for fabricating superhydrophobic fabrics with excellent hydrophobic and fireproof performances using an alkali‐catalyzed reaction to produce hydrophobic silicone nanofilaments (SNFs) is proposed. Experimental results show that poly‐methylhydrosiloxane (PMHS) can be transformed into SNFs in situ by thermal curing at 120 °C for 30 min under alkaline condition. Adopting this reaction method, the prepared superhydrophobic flexible fabric shows excellent superhydrophobic property with a contact angle of 168°. The oxygen index of the treated fabric is found to increase from 18.77% to 29.40%. Thermogravimetric result shows that the prepared fabric possesses a flame‐retardant property with fire resistance of thermal decomposition temperature of 130 °C. The fabricated fabric has good durability, which maintains superhydrophobicity after being soaked in acid solution (pH = 1) and salt solution (pH = 7) for 36 h. This fabrication process has great potential application for textiles and its composite materials.

Electrophilic-nucleophilic properties as a factor in the formation of antifriction and hydrophobic properties of surface-modified metals with ammonium and organosilicon compounds

Stabilisation of the functional properties of dispersed and compact metals, as well as the regulation of their reactivity, improvement of water-repellent, antifriction and anti-corrosion properties by creating the protective films on the surface is an urgent problem in relation to obtaining new materials. Previously, research conducted at REC “Nanotechnology” of the St. Petersburg Mining University proved that chemisorption of ethylhydridesiloxane vapours together with surfactants based on quaternary ammonium compounds has a beneficial effect on the water-repellent properties of metals. In order to obtain the physicochemical mechanism of the hydrophobisation of the surface of modified dispersed metals for the firsttime, the study of the electrophilic-nucleophilic properties of the active substances of the surface modifiers of metals was carried out using the methods of quantum-chemical modelling using HyperChem software package. The dipole moment, energy of the highest occupied and the lowest unoccupied molecular orbitals, electrophilic-nucleophilic properties were determined. The series of enhancement of ucleophilic/electrophilic properties and dipole moment for modifiers were obtained. The donor-acceptor properties, the differences in the characteristics of the molecules of alkamon, triamon, and hydrophobic silicone organic liquid were quantitatively and qualitatively established. The regularities of the formation of hydrophobic and antifriction properties in the composition of industrial oil I-20-surface-modified metal with various electrophilic-nucleophilic properties of the applied substances

The effect of surfactant concentration on nanoparticles surface wettability during wettability alteration of oil-wet carbonate rock

Previous studies reported that the presence of surfactant increases nanoparticles surface wettability by in-situ surface activation. On the other hand, the excess of surfactant concentration has an inverse effect on particle hydrophobicity by altering it to be hydrophilic back. Hence, this study presents an experimental investigation of wettability alteration by using a surfactant-nanoparticles system by using cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) surfactant, and hydrophilic silicon dioxide (SiO2) and partially hydrophobic silicon dioxide (PH SiO2) nanoparticles. The nanoparticles surface wettability and the wettability alteration of oil-wet carbonate rock were measured by using the contact angle method. The result shows that the contact angle of the oil-wet carbonate rock was most reduced by using CTAB-hydrophilic SiO2, from 112.00o to 28.35o. The excess of surfactant concentration (beyond CMC) shows an inverse effect on particle surface wettability, however, induces the water-wetness of the carbonate rock. Besides, the hydrophilic SiO2 shows a more effective effect as a wettability modifier than the PH SiO2, in the absence and presence of CTAB or SDS surfactant.

Photosensitizing nanoclays for efficient cell uptake and in vitro photodynamic therapy

In this study a straightforward strategy to deliver photosensitizing molecules into cancer cells by using Laponite RD® (LAP) nanodisks as carrier is presented. We report the application of LAP functionalized with a highly hydrophobic Silicon phthalocyanine photosensitizer (SiPc) for efficient cell uptake and photodynamic therapy (PDT) of MCF-7 breast cancer cells in vitro. This inorganic-organic hybrid nanomaterial caused a threefold increase in intracellular ROS levels and 99.7% of cancer cell inactivation after light treatment (630 nm; fluency of 108 J/cm²). With its theranostic capabilities (simultaneous fluorescence and singlet oxygen generation), uptake into cancer cells was monitored to control the photo-inactivation. The functionalized nanodisks already proved to be an efficient photo-inactivator of pathogenic Gram-(+) bacteria and were previously reported as LS10. By extending the use of LS10 to PDT of cancer cells, it is an example of a photosensitizer functionalized nanoclay with multipurpose drug characteristics, demonstrating an intriguing potential for future phototherapeutic studies and applications.

Room-Temperature Diffusion-Induced Extraction for Perovskite Nanocrystals with High Luminescence and Stability.

Metal halide perovskite nanocrystals (NCs) serve as a kind of ideal semiconductor for luminescence and display applications. However, the optoelectronic performance and stability of perovskite NCs are mainly subjected to current ligand strategies since these ligands exhibit a highly dynamic binding state, which complicates NC purification and storage. Herein, a method named diffusion-induced extraction is developed for crystallization (DEC) at room temperature, in which silicone oil serves as a medium to separate the solvent from perovskite precursors and diethyl ether promotes the nucleation, leading to highly emissive perovskite NCs. The formation mechanism of NCs using this approach is elucidated, and their optoelectronic properties are fully characterized. The resultant NCs ink exhibits a high photoluminescence quantum yield (PLQY) over 90% with a narrow full width at half maximum of 17nm. The DEC method strengthens the interaction between ligand and NCs via the hydrophobic silicone oil. Therefore, the NCs maintain almost 95% of their initial PLQYs after aging more than seven months in air. The findings will be of great significance for the continued advancement of high PLQY perovskite NCs through a better understanding of formation dynamics. The DEC strategy presents a major step forward for advancing the field of perovskite semiconductor nanomaterials.