Hydrophobic Modification Research Articles

Molecular dissociation of DTMS tailoring cellulose regeneration and hydrophobic modification for building highly transparent cellulose films

Earth has become depleted of oil and has suffered from the misuse of non-biodegradable plastics. Significant efforts have been dedicated to addressing the application flaws of cellulose as a substitute for plastics derived from petroleum. One of key defects was non-hydrophobic nature which highly influenced the mechanical properties of cellulose material during practical uses. Here, an innovative method was proposed to achieve hydrophobic modification of cellulose films through the molecular dissociation of dodecyltrimethoxysilane (DTMS) without the use of any toxic agents during the cellulose regeneration process. The hydrophobic (water contact angle of 118°), transparent (transmittance of 85%), and high-strength (70 MPa) DC films (cellulose films modified by DTMS) were successfully fabricated via cellulose regeneration process tailored by DTMS after molecular dissociation. The DC films stood out in both hydrophobicity and strength compared with several commercial plastics and the possible hydrophobic mechanism was proposed. Furthermore, the obsession with smart sensing abilities in DC films has made it a potential tool for monitoring baby diapers. Therefore, unlike conventional concepts, the methodology we adopted is simple and efficient, and it also eliminates the need for cellulose and replaces it with plastics.

Effect of Paraffin Oil Nanoemulsion as a Hydrophobic Modifier on Cement Paste Workability and Hydration

Effect of Paraffin Oil Nanoemulsion as a Hydrophobic Modifier on Cement Paste Workability and Hydration

Double-layer coated particles formed by one-step method based on microfluidic technology

This study used a microfluidic device with a focus-wrapping structure to create double-layer calcium alginate hydrogel drug particles in a one-step process. We validated the double-layer structure of the particles using both a fluorescence and regular light microscope. Curcumin and catalase were distributed independently in each layer, and we expected that such structure could play a role in the slow release of drugs. This scheme greatly reduces the need of hydrophilic and hydrophobic modification treatment, therefore greatly simplifies the experimental process. In the meantime, the requirement for injecting drugs into osteoarthritis and other diseases is expected to be realized, expanding the use of hydrogel in the medical field, because the microsphere is easy to generate, inexpensive, and strong in internal drug substitutability.

In-Silico Method for Predicting Pathogenic Missense Variants Using Online Tools: AURKA Gene as a Model.

In-silico analysis provides a fast, simple, and cost-free method for identifying potentially pathogenic single nucleotide variants. To propose a simple and relatively fast method for the prediction of variant pathogenicity using free online in-silico (IS) tools with AURKA gene as a model. We aim to propose a methodology to predict variants with high pathogenic potential using computational analysis, using AURKA gene as model. We predicted a protein model and analyzed 209 out of 64,369 AURKA variants obtained from Ensembl database. We used bioinformatic tools to predict pathogenicity. The results were compared through the VarSome website, which includes its own pathogenicity score and the American College of Medical Genetics (ACMG) classification. Out of the 209 analyzed variants, 16 were considered pathogenic, and 13 were located in the catalytic domain. The most frequent protein changes were size and hydrophobicity modifications of amino acids. Proline and Glycine amino acid substitutions were the most frequent changes predicted as pathogenic. These bioinformatic tools predicted functional changes, such as protein up or down-regulation, gain or loss of molecule interactions, and structural protein modifications. When compared to the ACMG classification, 10 out of 16 variants were considered likely pathogenic, with 7 out of 10 changes at Proline/Glycine substitutions. This method allows quick and cost-free bulk variant screening to identify variants with pathogenic potential for further association and/or functional studies.

Preparation of TiO2–SiO2–CaCO3 composite opacifier by hydrophobic agglomeration and mechanism of inhibiting glaze yellowing

This study investigates the preparation of TiO2–SiO2–CaCO3 composite opacifier (Ti–Si–Ca) and its application in sanitary ceramic glazes. This approach involved hydrophobic agglomeration through surface-induced hydrophobic modification of TiO2, SiO2 and CaCO3 particles, along with the interactions between the hydrophobic carbon chains of modifiers. The Ti–Si–Ca formed a uniform coating with well-dispersed TiO2 and SiO2 particles on the CaCO3 surface and strong bonds formed among TiO2, SiO2 and CaCO3 through interpenetration of the organic carbon chains on the surface. The Ti–Si–Ca was added to the basic glazes of sanitary ceramics at a proportion of 15.5 % and fired at 1125 °C for 4 h. The resulting white ceramic glazes had chromaticity values of L*, a*, and b* at 93.76, −0.73, and 3.89, respectively, demonstrating superior glaze opacity and whiteness compared to glazes made with a ZrSiO4 opacifier (L* 90.30, b* 4.50). Glass and titanite phase make up the majority of the Ti–Si–Ca ceramic glazing layer of, with titanite serving as the opacified phase. Elimination of organic groups in Ti–Si–Ca during glaze firing formed interfacial chemical bonds among TiO2, SiO2 and CaCO3, which facilitated the synthesis of titanite from the three components at high temperatures. The Ti–Si–Ca was a highly opaque glaze without yellowing because the organic groups of Ti–Si–Ca were removed and interfacial chemical bonds formed among the TiO2, SiO2 and CaCO3 in the low-temperature stage of glaze firing. This transformed the three phases into titanite at high temperature and eliminated free TiO2. The formation of rutile TiO2, which has a yellow hue, at high temperatures was inhibited. This study provides a novel approach for low-energy preparation of TiO2–SiO2–CaCO3 composite opacifiers and addresses the challenge of replacing ZrSiO4 with TiO2 in ceramic opacifiers.

Biocompatible hydrophobic cross-linked cyclodextrin-based metal-organic framework as quercetin nanocarrier for enhancing stability and controlled release

Cyclodextrin-based metal-organic framework (CD-MOF) has been widely used in various delivery systems due to its excellent edibility and high drug loading capacity. However, its typically bulky size and high brittleness in aqueous solutions pose significant challenges for practical applications. Here, we proposed an ultrasonic-assisted method for rapid synthesis of uniformly-sized nanoscale CD-MOF, followed by its hydrophobic modification through ester bond cross-linking (Nano-CMOF). Proper ultrasound treatment effectively reduced particle size to nanoscale (393.14 nm). Notably, carbonate ester cross-linking method significantly improved water stability without altering its cubic shape and high porosity (1.3 cm3/g), resulting in a retention rate exceeding 90% in various media. Furthermore, the loading of quercetin did not disrupt cubic structure and showcased remarkable storage stability. Nano-CMOF achieved controlled release of quercetin in both aqueous environments and digestion. Additionally, Nano-CMOF demonstrated exceptional antioxidant (free radical scavenging 82.27%) and biocompatibility, indicating its significant potential as novel nutritional delivery systems in food and biomedical fields.

Hydrophobic Modification of Small-Pore Pd-SSZ-13 Zeolites for Catalytic Methane Combustion

Hydrophobic Modification of Small-Pore Pd-SSZ-13 Zeolites for Catalytic Methane Combustion

Hydrophobic modification of walnut shell biomass-derived porous carbon for the adsorption of VOCs at high humidity

Volatile organic compounds (VOCs) often contain water vapor in their exhaust emissions, resulting in the deterioration of the adsorption capacity of activated carbon (AC). A hydrophobic walnut shell biomass-derived AC using polytetrafluoroethylene (PTFE) and polydimethylsiloxane-coated SiO2 (PDMS/SiO2) was developed to improve the selectivity of VOCs under high humidity conditions. These modified ACs were systematically characterized, and dynamic adsorption behaviors of VOCs such as toluene, acetone and their mixtures at the relative humidity (RH) between 0 and 90 % were conducted. The results showed that walnut shell biomass-derived AC has large specific surface area (1853 m2/g) and total pore volume (1.27 cm3/g), strong hydrophilicity (water contact angle of 6.3°), abundant oxygen-containing groups (OH, CO, CO) and aromatic rings. The coating of PDMS/SiO2-PTFE reduces the surface area and total pore volume of AC, but it creates a double-layer rough structure on the AC surface and introduces CF and SiOSi hydrophobic groups, which achieves a water contact angle of 152.8° for 25PSP/AC. The Yoon-Nelson model is suitable to describe the dynamic adsorption process of single- toluene or acetone under dry/humid condition but not suitable for their mixtures. At RH 90 %, PDMS/SiO2-PTFE modified AC significantly increases the adsorption capacity of toluene but is not obviously improved for acetone, which is due to the different polarity of toluene and acetone. PDMS/SiO2-PTFE films on AC have good thermal stability before 500 °C and the hydrophobicity does not change after multi-regeneration at 200 °C. Therefore, PDMS/SiO2-PTFE modified AC has shown great potential as adsorbent to remove the toluene from the humid condition.

Construction of hydrophilic-hydrophobic domains in Bi2O3/nitrogen-doped carbon electrode to boost CO2-to-formate conversion

Bi has drawn attention in catalyzing the electrochemical CO2-to-formate conversion due to promising selectivity and low cost, but the process suffers from low activity. Herein, we introduce nitrogen-doped carbon (NC) support with hydrophobicity modification to enhance the activity of a binder-free Bi2O3 electrode. Formate partial current on the NC supported Bi2O3 electrode almost doubles compared to Bi2O3 on unmodified support. Furthermore, the hydrophobicity modification with polytetrafluoroethylene (PTFE) significantly extends the stability of NC supported Bi2O3 by diminishing flooding. It also maintains >90% formate selectivity at a broad potential range from −0.87 to −1.27 V (vs. RHE) and shows a formate partial current density of −100 mA cm−2 at −1.37 V (vs. RHE) in 0.5 M KHCO3. The improvement is attributed to the synergetic effects of the hydrophilic active sites and the hydrophobic PTFE modified NC support. The unique structure promotes the reactants transport and thus maximizes the active site utilization at the triple-phase interface. This facile microenvironment regulation can be extended to other applications involving gaseous-aqueous phases.

Hydrophobic Modification of Bi2O3-Doped Si-Ti Composite Film on a Wood Surface

In order to improve the hydrophobicity of the composite film on the wood surface, the wettability of the wood surface and its morphology, chemical structure, roughness and free energy changes were investigated in this paper after modification treatments with different volume fractions of octadecyltrichlorosilane (OTS) and polydimethylsiloxane (PDMS). It can be found that the water contact angle and surface roughness of the hydrophobically modified wood increased with the increase in volume fraction, but the overall effect of OTS hydrophobic modification was better than that of PDMS, and a maximum water contact angle of up to 140.8° could be obtained at a volume fraction of 2% of OTS. In addition, the intensity of the stretching vibration peak of -OH was weakened after the modification, while the intensity of the stretching vibration peak of -CH2- was enhanced, resulting in an increase in hydrophobicity. At the same time, it can be found that the surface free energy of the modified wood specimens was reduced, which shows that OTS and PDMS improve the surface hydrophobicity of the wood by increasing the surface roughness and decreasing the surface free energy together. Finally, the hydrophobically modified Bi2O3-doped silica–titanium composite film still possessed high photocatalytic degradation activity for rhodamine B and gas formaldehyde, and the degradation rate could reach more than 90%.

Plant fiber-reinforced green composite: A review on surface modification, properties, fabrications and applications

Plastic pollution has become a persistent challenge globally. The extensive production of disposable plastics overwhelms the world's ability to cope with. These non-biodegradable plastics accumulating in landfills, rivers, and seas cause severe damage to wildlife and the environment. The utilization of biopolymer is a possible alternative to petroleum-based plastics. Polybutylene succinate (PBS), polyhydroxyalkanoates (PHA), polylactic acid (PLA), poly(ε-caprolactone) (PCL), cellulose, chitin, and thermoplastic starch are mostly used biopolymers with promising properties. There are challenges too. Properties including brittleness, low thermal stability, low strength, and poor chemical barrier properties are the challenges to replacing plastics material. Reinforcing natural fibers as an alternative to non-biodegradable synthetic fiber with biopolymer matrices improves the properties of the material significantly. Flax, kenaf, jute, ramie, and hemp are a few agro-based fibers that are generally reinforced with biopolymer matrices. These composites are known as green composites. In order to create an interfacial bond between hydrophilic fiber and hydrophobic biopolymer surface modification of natural fiber is needed. There are many physical and chemical methods of surface medication which enhance roughness, wettability as well as hydrophilicity, lowers moisture absorption, improve the interfacial bond, and also enhance the tensile properties of natural fiber. The review is on the classification of biopolymers, natural fibers and their properties as well as the surface modification techniques for plant fibers. Moreover, the fabrication, mechanical and chemical properties including biodegradation of different green composites and the application of green composites, are also discussed here.

An eco-friendly and low-cost superhydrophobic alkali-activated Portland slag cement mortar

Alkali-activated slag cement (AASC) has shown immense potential for application as a low-carbon and eco-friendly cementitious material. It’s crucial to modify the AASC with superhydrophobic property to obtain excellent durability performance. In this paper, low-cost and non-toxic stearic acid (SA) is selected as a hydrophobic agent to impart integral hydrophobic property to the alkali-activated Portland slag cement mortar (AAPSCM). The SA-modified AAPSCM (M-AAPSCM) shows superhydrophobicity with a contact angle of 150.6° and a sliding angle of 9.5°, even when hammered to reveal its broken inner structure. The characterization analysis indicates that stearic acid not only successfully grafts onto the mortar surface but also forms calcium stearate, which successfully reduces the surface energy of the material. Combined with the porous rough structure constructed by medium sand and ethanol volatilization, the originally hydrophilic material achieves hydrophobic modification under the dual synergistic effect. The M-AAPSCM reached a compressive strength of 20.8 MPa after 28 days of curing, satisfying the requirements for hydraulic engineering applications. And the M-AAPSCM not only exhibits an excellent self-cleaning ability against contaminants like sand particles and chalk powder, but also demonstrates remarkable mechanical robustness, even after being subjected to blade scratching or mechanical fracture. Concurrently, the initial and final setting times of M-AAPSCM were determined to be 32 minutes and 41 minutes respectively, demonstrating its rapid-setting characteristic. Additionally, following the hydrophobic modification, AAPSCM effectively overcomes its inherent issues of severe autogenous shrinkage and poor carbonation resistance. Furthermore, when compared with the ordinary AAPSCM (O-AAPSCM), the durability of the M-AAPSCM against dry-wet cycles, icing, and freeze-thaw cycles is significantly enhanced.

ZIF-8/GO/PDMS modified cotton fabric to form a hierarchical-structure coating for fast oil/water separation

An efficient hydrophobic and lipophilic cotton fabric was designed for oil/water separation. ZIF-8 (zeolitic imidazolate framework-8) nanocrystals were synthesized and subsequently uniformly mixed with a GO (graphene oxide) dispersion, and then the cotton fabric was immersed in a pre-crosslinked PDMS (polydimethylsiloxane) solution and the mixture of ZIF-8 and GO to form rough and dense surface morphology and to achieve hydrophobic modification. Its surface morphologies, chemical structures, contact angles, and oil/water separation performances were characterized. The ability of prepared fabric with a separation efficiency was better than 95 % on average for various types of oil/water mixtures demonstrated the hydrophobic/oleophilic property, meanwhile, demonstrated a noteworthy degree of durability. It holds significant practical implications for the development of environmentally friendly and highly efficient materials for oil/water separation.

The potency of hydrophobic modification of alginate for a self-assembly matrix in fish oil encapsulation

To act as an emulsifier and a matrix for fish oil encapsulation, alginate is required to be modified due to its hydrophilicity. The purpose of this study was to modify alginate using dodecenyl succinic anhydride (DSA) under pH-controlled conditions and to apply it for stabilizing emulsion and encapsulating fish oil. The modification that followed the first-order reaction improved the hydrophobic properties of alginate as shown by the reduction of surface tension but improving the water contact angle, with CMC of 0.18 mg/l. A higher concentration of modified alginate was better in stabilizing fish-oil emulsion than the native one, as supported by the results of zeta potential, viscosity, and droplet size of the emulsion. Freeze-dried particle of this modified alginate emulsion showed better encapsulation efficiency and oxidation protection ability. Thermal properties of alginate were changed after hydrophobic modification and oil encapsulation. The freeze-dried particles of this modified alginate emulsion showed better encapsulation efficiency and protection ability. This study confirmed the protective ability of the modified alginate using DSA as an oil-based active ingredient encapsulant.

Effects of particle size and modifier amount on hydrophobicity of as-synthesized and modified nano-silica spheres

Superhydrophobic coatings possess dust-proof and self-cleaning characteristics. Reducing surface energy and improving nanoscale roughness is considered to be crucial for the development and design of superhydrophobic coatings as they can result in significant reduction in the adhesion between solid surfaces and water droplets. In this work, silica spheres were synthesized and hydrophobically modified using the Stober process. Surface morphology and particle size as well as grafting modification effect, grafting quality, hydrophobic properties, and chemical hydrophobic modification mechanism of synthesized silica spheres were analyzed. Results show that the size of synthesized particles is significantly correlated with the concentration of ammonia catalyst, and their hydrophobic properties are significantly correlated with the amount of dichlorodimethylsilane (DCDMS) modifier. Superhydrophobic behavior is obtained for modified silica sphere (MSS) samples with particle sizes of 850, 400, 320, and 120 nm by varying the molar ratio (MR) of DCDMS to silica spheres (MR = 4, 8, and 16). The optimal amount of modifier is closely related to the size of spheres with fixed mass of silica spheres. In addition, large MSS arrays can provide rougher surfaces and thus trap more air within the voids, which resulting in stable hydrophobic properties. This work can provide guidance for the design of superhydrophobic coatings.

Structural and Transport Properties of Hydrophilic and Hydrophobic Modified Ionomers in Proton Exchange Membrane Fuel Cells.

The sluggish commercial application of proton exchange membrane fuel cells (PEMFCs) with low Pt loading is chiefly hindered by concentration polarization loss, particularly at high current density regions. Addressing this, our study concentrates on the ionomer membranes in the cathode catalyst layer (CCL) and explores the potential of incorporating additional hydrophilic or hydrophobic components to modify these ionomers. Therefore, an all-atom model was constructed and for the ionomer and hydrophilic and hydrophobic modifications were implemented via incorporating SiO2 and PTFE, respectively. The investigation was conducted via molecular dynamics (MD) simulations to predict the morphology and structure of the ionomer and analyze the kinetic properties of oxygen molecules and protons. The simulation results elaborate that the hydrophilic and hydrophobic modifications favor the phase separation and the self-diffusion coefficients of oxygen molecules and protons are enhanced. Considering the hydration level of the ionomer films, hydrophilic modification facilitates mass transfer under low-hydration-level conditions, while hydrophobic modification is more effective in optimizing mass transfer as the hydration level increases. The optimal contents of SiO2 and PTFE for each hydration level in this work are 9.6% and 45%, respectively. This work proposes a reliable model and presents a detailed analysis of hydrophilic and hydrophobic modifications, which provides theoretical guidance for quantitative preparations of various composite membranes.

Oxidized cellulose as bio‐adhesive for hydrophobic lignocellulosic bioplastic

AbstractThis study presents a novel hydrophobic lignocellulosic bioplastic from corn stover reinforced by oxidized cellulose and in situ regenerated lignin. Cellulose‐lignin mixture as a matrix was obtained by acid‐recyclable deep eutectic solvent (DES) pretreatment of corn stover in mild conditions. Triethoxy(octyl)silane (C14H32O3Si) was employed to improve the water stability of the bioplastic by vapor deposition. The results show that the hydrophobic bioplastic has a high tensile strength, measuring 62.36 MPa. The water contact angle of the bioplastic was increased from 8.50° to 121.9° after hydrophobic modification. We prepared oxidized cellulose‐reinforced cellulose paper by different particle size distributions of oxidized cellulose to investigate the reinforcement of oxidized cellulose. The tensile strength of oxidized cellulose cellulose paper increased from 14.41 to 21.18 MPa with the addition of oxidized cellulose. The zeta potential of oxidized cellulose is −47.99 mV, which shows a more negative charge due to carbonyl groups. The repulsive force of oxidized cellulose contributes to the formation of a brick‐and‐mortar microstructure with cellulose‐lignin mixture. It demonstrates that oxidized cellulose can act as bio‐adhesives and has a good toughening effect on the mechanical properties of bioplastic.Highlights Lignocellulosic bioplastic was prepared by DES pretreatment of corn stover. Oxidized cellulose was used to reinforce the lignocellulosic bioplastic. The tensile strength of the bioplastic was 62.36 MPa after the reinforcement process. Trieth‐oxy(octyl)silane was employed to improve water stability. The water contact angle of the bioplastic was increased from 8.50° to 121.9°.

Robust and Durable Superhydrophobic Coatings with Antipollution Flashover Performance via Silane-Modified Polyurea.

The inadequate hydrophobicity and the degradation in usage seriously hampered the applications of the existing antipollution flashover coatings. In this paper, a superhydrophobic polyurea coating with antipollution flashover ability was fabricated through chemically grafting the silica onto the chains of polyurea by utilizing silane coupling agent and hydrophobic modification. It is demonstrated that the coating exhibits outstanding antipollution flashover performances. Noteworthy, the surface pollution flashover voltage has been increased by 33.8% compared with the room temperature vulcanizing silicone rubber (RTV silicone rubber). In addition, the volume resistivity is above 1.0 × 1012 Ω·m, and the dielectric strength achieves to 28.85 kV/mm, which represents excellent insulating property. Furthermore, the superhydrophobic polyurea coating exhibits outstanding abrasion resistance, adhesion, acid-base resistance, and durability. As a result, it holds great promise for use in preventing pollution flashover in electrical insulators.

Phase Change Material Boosting Electricity Output and Freshwater Production through Hierarchical‐Structured 3D Solar Evaporator

AbstractIntermittent sunlight irradiation severely limits the performance of solar evaporators for electricity output and freshwater production. To address this issue, a hierarchical‐structured three‐dimentional (3D) solar evaporator to simultaneously enhance output voltage and freshwater production by integrating a paraffin‐type phase change material (PCM) with a circular concave‐shaped 3D supporter covered with a carbon‐black‐nanoparticles‐modified poly(ethylene terephthalate) fabric (PMCB) is developed. In this developed 3D solar evaporator, the 3D‐printed supporter can trap sunlight to improve solar energy absorption, and the PMCB obtained from hydrophilic and hydrophobic modification can adequately absorb sunlight for electricity generation and water evaporation, resulting in a maximum output voltage of 3.51 V and a high evaporation rate of 4.0 kg m−2 h−1 under natural sunlight illumination. Owing to the introduction of the PCM, the 3D solar evaporator obtains a decrease in the time required for charging a capacitor by 57.9% and an increase in freshwater production by 29.9% compared to the counterpart without a PCM. Through rationally utilizing the solar photothermal energy stored by the PCM and innovatively integrating the PCM and PMCB in a hierarchical‐structured 3D supporter, the developed 3D solar evaporator exhibits great application potential for simultaneous electricity generation and freshwater supply under intermittent solar irradiation.

Hydrophobic modification of zeolite-supported platinum catalysts for complete oxidation of toluene

Zeolite-supported noble metal nanoparticles have been reported as active catalysts for complete oxidation of volatile organic compounds (VOCs) due to the combination of advantages of zeolite supports and noble metal species, where introducing more Al species (reduction of SiO2/Al2O3 ratios, SAR) and increasing hydrophobicity for zeolite supports are favorable for the complete oxidation of VOCs. Unfortunately, introduction of more Al species in the zeolite frameworks normally reduces the hydrophobicity of zeolite crystals. To overcome this problem, we rationally synthesize hydrophobic zeolites with low SAR by anchoring methyl group, exhibiting exceptionally catalytic performances in the complete oxidation of toluene at very low temperature (T90 at 144 °C) after loading Pt species (1 wt%). Characterizations of the catalysts show a vital role of hydrophobic zeolites for adsorption of more toluene and fast desorption of water. The strategy for preparation of hydrophobic zeolite-supported noble metal catalysts might offer an alternative way to develop highly efficient heterogeneous catalysts for the complete oxidation of VOCs in the future.