Size Of Silica Nanoparticles Research Articles

Chitosan-Based Charge-Controllable Supramolecular Carrier for Universal Immobilization of Enzymes with Different Isoelectric Points.

Electrostatic adsorption is an enzyme immobilization method that effectively maintains enzyme activity and exhibits considerable binding efficiency. However, enzymes carry different charges at their respective reaction pH levels, which prevents the use of the same carrier to immobilize enzymes with different charges. In this study, we employed a template-mediated polysaccharide-enzyme coupling self-assembly strategy to develop a charge-controllable supramolecular immobilization carrier by regulating the charge properties of carboxymethyl chitosan, enabling the universal immobilization of enzymes with different charge levels across a range of reaction pH values. By using silica nanoparticles of certain sizes as templates, the size of the carrier can be precisely controlled and the hollow network structure formed after removing the template can effectively reduce mass transfer resistance. Trypsin and papain are used as model enzymes, and the experimental results show that the supramolecular self-assembly immobilization strategy does not disrupt the secondary structure of the enzyme molecules. After 2 h of reaction, the enzyme activities of immobilized papain and immobilized trypsin are 13.2% and 7.7% higher than those of the free enzymes, respectively. After 10 consecutive reactions, the enzyme activities of immobilized papain and immobilized trypsin retained 56.3% and 64.3% of their initial values, respectively.

Synthesis and characterization of mesoporous silicate as core and low generation polyamidoamine dendrimer as shell for delivery of 5-fluorouracil from their nano complex

Modern nanomedicine delivers drugs to malfunctioning cells. Several synthetic processes can change the shape, particle size, polydispersity index, surface area, and porosity of mesoporous silica nanoparticles (MSNs). Polyamidoamine (PAMAM) dendrimers are attractive polymers with circular forms, uniform distribution, well-structured branching, internal cavities, and surface terminal groups. The objective of this study is to deliver 5-fluorouracil (5-FU) as passive targeting to carcinogen cells via MSN-PAMAM-G3 nanoparticles. This study involved the direct and adaptable synthesis of MSN as the core vehicle, together with third-generation PAMAM dendrimers as the vehicle shell, with the goal of delivering the 5-FU in a targeted and controllable manner. Tetraethyl orthosilicate (TEOS) and cetyltrimethylammonium bromide (CTAB) are used as templates to make the center nanoparticle. Methyl acrylate (MA) and ethylenediamine (EDA) are monomers that cause the formation of branches in PAMAM. The obtained particles were fully characterized in terms of particle size, polydispersity index, zeta potential, thermal behavior, morphology, pore diameter, pore volume, and specific surface area. The particle size of MSN-PAMAM-G3s showed around 187.71 ± 3.97 nm, with a polydispersity index of 0.17 ± 0.01 and zeta potential of 32.17 ± 1.30 mV. By reducing the ratio of drug to vehicle from 1 to 0.25, a significant increase in the EE% of 5-FU from 21.36 ± 0.70 to 43.12 ± 0.67 was observed. The release of 5-FU from the vehicle (5-FU@MSN and 5-FU@MSN-PAMAM-G3) was shown to be considerably higher in an acidic medium (pH = 5.5) in comparison to a neutral medium (pH = 7.4) (P-value<0.05). Furthermore, in both acidic and neutral conditions, 5-FU release was sustained from the vehicle rather than the 5-FU solution. Our research revealed that the MSN-PAMAM-G3 nanoparticles effectively regulated the encapsulation and release of 5-FU, providing pH-sensitive and sustained medication delivery. It is asserted that this nanocarrier has the potential to effectively deliver 5-FU to cancer cells.

Regulation of IFP in solid tumours through acoustic pressure to enhance infiltration of nanoparticles of various sizes

Numerous nanomedicines have been developed recently that can accumulate selectively in tumours due to the enhanced permeability and retention (EPR) effect. However, the high interstitial fluid pressure (IFP) in solid tumours limits the targeted delivery of nanomedicines. We were previously able to relieve intra-tumoural IFP by low-frequency non-focused ultrasound (LFNFU) through ultrasonic targeted microbubble destruction (UTMD), improving the targeted delivery of FITC-dextran. However, the accumulation of nanoparticles of different sizes and the optimal acoustic pressure were not evaluated. In this study, we synthesised Cy5.5-conjugated mesoporous silica nanoparticles (Cy5.5-MSNs) of different sizes using a one-pot method. The Cy5.5-MSNs exhibited excellent stability and biosafety regardless of size. MCF7 tumour-bearing mice were subjected to UTMD over a range of acoustic pressures (0.5, 0.8, 1.5 and 2.0 MPa), and injected intravenously with Cy5.5-MSNs. Blood perfusion, tumour IFP and intra-tumoural accumulation of Cy5.5-MSNs were analysed. Blood perfusion and IFP initially rose, and then declined, as acoustic pressure intensified. Furthermore, UTMD significantly enhanced the accumulation of differentially sized Cy5.5-MSNs in tumour tissues compared to that of the control group, and the increase was sevenfold higher at an acoustic pressure of 1.5 MPa. Taken together, UTMD enhanced the infiltration and accumulation of Cy5.5-MSNs of different sizes in solid tumours by reducing intra-tumour IFP.

Influence of electrophoretic deposition of micro- or nanosized silica particles on the microstructure of carbon fibers and their bond behavior with cementitious matrices

The application of carbon fiber (CF) reinforced cementitious composites is often restricted by the poor load transfer between the components. In this study, two reactive coating materials—nano-silica and micro-silica—are utilized to modify the CF surfaces via an electrophoretic deposition approach. These negatively charged particles are able to be electrosorbed onto the fiber surfaces under a constant electrical field according to the zeta and cyclic voltammetry measurements. After surface treatment, XRD analysis of CFs showed an increase in graphite crystallite thickness and decrement in interlayer spacing d002\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${d}_{002}$$\\end{document}, significantly affecting the fiber diameters. Additionally, the lengths of crystallites were reduced, which can impair the fiber strength and their temperature stability. Single fiber pullout tests exhibited that the interfacial bonding can be clearly enhanced by both reactive coatings. Microscopic observation revealed that C–S–H gel and calcite structures can be formed near the fiber surfaces after immersion in cement pore solution owing to pozzolanic reaction and nucleation effect, tremendously heightening both chemical and mechanical interaction between fiber and cement. Finally, based on a detailed micromechanical analysis, the reinforcing mechanisms between the differently modified fibers and the cementitious matrix were elaborated and discussed.Graphical abstract

Factors Affecting Silica/Cellulose Nanocomposite Prepared via the Sol-Gel Technique: A Review.

Cellulose/silica nanocomposites, synthesised through the sol-gel technique, have garnered significant attention for their unique properties and diverse applications. The distinctive characteristics of these nanocomposites are influenced by a range of factors, including the cellulose-to-silica ratio, precursor concentration, pH, catalysts, solvent selection, temperature, processing techniques, and agitation. These variables play a pivotal role in determining the nanocomposites' structure, morphology, and mechanical properties, facilitating tailoring for specific applications. Studies by Raabe et al. and Barud et al. demonstrated well-deposited silica nanoparticles within the interstitial spaces of cellulosic fibres, achieved through TEOS precursor hydrolysis and the subsequent condensation of hydroxyl groups on the cellulose fibre surface. The introduction of TEOS established a robust affinity between the inorganic filler and the polymer matrix, emphasising the substantial impact of TEOS concentration on the size and morphology of silica nanoparticles in the final composites. The successful functionalisation of cellulose fibres with the TEOS precursor via the sol-gel method was reported, resulting in reduced water uptake and enhanced mechanical strength due to the strong chemical interaction between silica and cellulose. In research conducted by Feng et al., the silica/cellulose composite exhibited reduced weight loss compared to the pristine cellulose matrix, with the integration of silica leading to an elevated temperature of composite degradation. Additionally, Ahmad et al. investigated the effects of silica addition to cellulose acetate (CA) and polyethylene glycol membranes, noting an increase in Young's modulus, tensile strength, and elongation at break with silica incorporation. However, concentrations exceeding 4% (w/v) resulted in significant phase separations, leading to a decline in mechanical properties.

Synthesis and characterization of monodispersed silica‐based shear thickening fluid for impact resistance applications

AbstractShear thickening fluid (STF), a highly concentrated mixture of nanosized silica particles in polyethylene glycol (PEG) is characterized by its quick transition to a stiff, solid‐like form under high shear rates. In this study, the modified Stöber synthesis approach was used for synthesizing the monodispersed spherical 300 nm silica nanoparticles. The rheological properties of the STF formulated using different silica loading were characterized. The Takshak model was tested to assess the rheological properties. The effect of the STFs on the impact resistance and yarn pull‐out force of the Kevlar® 802 fabric was determined. The uniformity in size of the silica nanoparticles facilitated more efficient packing within the fluid matrix, resulting in the formation of networks or structures that enhance shear thickening behavior. The STF with 70% silica exhibited the best peak viscosity of 45.8 Pa.s. Upon impregnation of this STF onto the Kevlar, a significantly high energy absorption (478.4%) compared to neat Kevlar, was observed. Moreover, the yarn pull‐out force for this system was found to be very high (435.8%). The reasons for the enhancement of the properties are explained. The novelty of this work lies in the synthesis of silica particles, analysis of the rheological properties, and interrelating the rheological properties with the characteristic parameters to define the impact characteristics. The improved properties underscore the suitability of synthesized STF for impact resistance applications.

Extracellular vesicles promote silica nanoparticle aggregation that inhibits silica-induced cytotoxicity

Amorphous silica has been approved as a food and pharmaceutical additive. However, its potential to enhance the carcinogenicity of epithelial cells is incontrovertible. With their expanded surface area per unit mass and distinctive cellular incorporation, nano-sized silica particles (nSPs) exhibit heightened cytotoxicity compared to micrometer-sized counterparts. The precise effect of nSPs on the generation of small extracellular vesicles (sEVs) within endosomes after cellular uptake remains unclear. In the present study, we explored the secretion of sEVs from cells and their functional implications following exposure to nSPs. Our findings demonstrate that nSP50 exposure not only induced epithelial-mesenchymal transition (EMT) but also promoted the maturation of multivesicular endosomes (MVEs) along with the secretion of sEVs in A549 cells. Inhibition of sEV secretion using GW4869 and apoptosis activator 2 exacerbated nSP50-induced EMT, indicating that sEV secretion may suppress EMT. Analysis of the function of sEV in a cell-free system revealed that co-incubation of sEVs with nSP50 led to the formation of micrometer-sized aggregates, which exhibited limited uptake efficiency within A549 cells. These results strongly suggest that the secretion of sEVs plays a protective role against the cytotoxicity attributed to nSP50 exposure.

Applications of Cu2+-Loaded Silica Nanoparticles to Photothermal Therapy and Tumor-Specific Fluorescence Imaging.

Copper-based nanomaterials have been employed as therapeutic agents for cancer therapy and diagnosis. Nevertheless, persistent challenges, such as cellular toxicity, non-uniform sizes, and low photothermal efficiency, often constrain their applications. In this study, we present Cu2+-loaded silica nanoparticles fabricated through the chelation of Cu2+ ions by silanol groups. The integration of Cu2+ ions into uniformly sized silica nanoparticles imparts a photothermal therapy effect. Additionally, the amine functionalization of the silica coating facilitates the chemical conjugation of tumor-specific fluorescence probes. These probes are strategically designed to remain in an 'off' state through the Förster resonance energy transfer mechanism until exposed to cysteine enzymes in cancer cells, inducing the recovery of their fluorescence. Consequently, our Cu2+-loaded silica nanoparticles demonstrate an efficient photothermal therapy effect and selectively enable cancer imaging.

Borax preparation from Na-B-Si-containing solution by carbonation and multi-step crystallization

The Na-B-Si-containing solution was derived from ludwigite ore through a two-step process involving soda-ash roasting and subsequent grind-leaching. This study employed a carbonation-crystallization approach to comprehensively utilize the valuable components in the solution, aiming to produce borax while simultaneously generating sodium carbonate and silica. The initial carbonation precipitation achieved a high desilication ratio of 95.54 % through nano-sized silica particle formation. Meanwhile, the boron conversion ratio reached 94 %, with negligible boron loss due to efficient metaborate-to-borate transformation. To guide the crystallization separation of Na2CO3 and Na2B4O7, phase diagrams of the ternary system (Na2CO3 + Na2B4O7 + H2O) were experimentally constructed at 308.15 k and 333.15 k. Crystallization was then conducted at 278.15 K for 2 h, yielding a Na2B4O7·10H2O product with 96.45 % purity. The remaining filtrate was evaporated and crystallized to obtain the Na2CO3 product, which can be reused in the previous roasting process.

Growth regulation mechanism of nano-silica based on new ammonia-based CO2 capture under external fields

Conventional CO2 capture technologies often focus on the simple capture process, while the absorption and high-value utilization of carbon capture products have profound significance, especially when combined with the utilization of biomass energy. Novel ammonia-based CO2 capture coupled with selective silicon dissolution was proposed with process regulation of external fields (i.e. magnetic field, microwave field, ultrasound field) used to prepare nano silica. The results show that the magnetic field plays a dual role of “vibration stirring” and adding energy (11.2 J/mol) on the formation and dispersion of nano silica. The specific surface area of nano-silica is increased from 140.24 m2/g to 280 m2/g by microwave field (250 W), and its “internal heating” promotes the formation of crystal nuclei. The ultrasonic field reduces the primary particle size of nano-silica by 3.17 nm, and inhibits the particle growth through cavitation and mechanical vibration. It would provide parameter support and optimization guidance for the low-cost high-quality nano silica for high-value utilization of ammonia-based CO2 capture products.

Simulation of optomechanical interaction of levitated nanoparticle with photonic crystal micro cavity.

We propose and analyze theoretically a promising design of an optical trap for vacuum levitation of nanoparticles based on a one-dimensional (1D) silicon photonic crystal cavity (PhC). The considered cavity has a quadratically modulated width of the silicon wave guiding structure, leading to a calculated cavity quality factor of 8 × 105. An effective mode volume of approximately 0.16 μm3 having the optical field strongly confined outside the silicon structure enables optical confinement on nanoparticle in all three dimensions. The optical forces and particle-cavity optomechanical coupling are comprehensively analyzed for two sizes of silica nanoparticles (100 nm and 150 nm in diameter) and various mode detunings. The value of trapping stiffnesses in the microcavity is predicted to be 5 order of magnitudes higher than that reached for optimized optical tweezers, moreover the linear single photon coupling rate can reach MHz level which is 6 order magnitude larger than previously reported values for common bulk cavities. The theoretical results support optimistic prospects towards a compact chip for optical levitation in vacuum and cooling of translational mechanical degrees of motion for the silica nanoparticle of a diameter of 100 nm.

The relationship between cellular microstructure and the mechanical properties of styrene/methyl methacrylate copolymer‐silica nanocomposite foams prepared by a supercritical CO2 blowing agent

AbstractStyrene/methyl methacrylate (St/MMA) copolymer‐silica nanocomposite foams were prepared using supercritical CO2 as blowing agent, and the relationships between their cellular microstructure and mechanical properties were investigated. The effects of nanosilica content, size, and surface chemistry on the foam's microstructure and properties were examined. Dispersion and distribution of silica nanoparticles with different surface chemistry in St/MMA copolymer nanocomposites were discussed. To determine the most suitable copolymer composition for incorporating silica nanoparticles, some operating conditions such as temperature and pressure were primarily examined to study their effects on the microstructure of resulting foams. In compressive mechanical properties of final foams, a considerably high value was obtained for the compressive strength of the foams of up to 9.5 MPa. The prepared low‐density (below 0.2 g/cm3) St/MMA copolymer microcellular foams can be used in green lost foam iron casting processes.Highlights Styrene/methyl methacrylate copolymer‐silica nanocomposite foams were prepared via supercritical CO2. Foams' cell size was changed by changing silica nanoparticle surface chemistry and size. The uniform cellular microstructure was achieved by nanosilica size increment. Increasing nanoparticle size improved the foam's mechanical properties. Low‐density foams were achieved for potential application in lost foam casting.

Functionalized borosilicate-silica-epoxy nanocomposite superhydrophobic coating for corrosion inhibition under harsh environment

Current work proposes a facile scheme for fabrication of robust superhydrophobic borosilicate-silica-epoxy nanocomposite coatings on steel substrate with hierarchical structures, capable of inhibiting corrosion under harsh environment. The scheme amalgamates the advantageous properties of three ingredients: acid resistant property of borosilicate glass, superhydrophobic features of functionalized silica nanoparticles and durability of epoxy resin. The various steps of synthesis include 1. ball milling of borosilicate glass to micron and submicron size (~500 nm to 1.5 μm) 2. grafting of silica nanoparticles (~20 nm, through stober method) on the borosilicate particles to form rough hierarchical structure and 3. preparation of stable dispersion of the nanoparticles in epoxy-based resin followed by coating through immersion technique. Efficacy of the scheme was established through morphological, durability and electrochemical impedance studies. The surface morphology revealed hierarchical structures of functionalized silica nanoparticles (size range 20–100 nm) grafted on micro-sized borosilicate particles, which sustained water droplets with contact angle as high as 164.5° ± 2°. Sandpaper abrasion test proved excellent durability retaining hydrophobicity up to 250 abrasion cycles. The prepared surface maintained notable interface stability under aggressive environment: 3 and 10 days under pH 1 and 13 respectively. The electrochemical study in 3.5 wt% NaCl aqueous solution showed significant decrease in corrosion current density of coated surface (0.3585 μA/cm2) compared to uncoated surface (43.918 μA/cm2) suggesting excellent corrosion resistance. The results highlight scope of using this robust coating for abrasive and harsh environment.

Nanopriming of Tomato (Solanum lycopersicum) Seeds Against Heavy Metal Stress During Germination and Seedling Formation

Abiotic stress can have a negative impact on plant growth. Heavy metal is one of the examples. One approach to overcome this issue is to use seed priming. The priming used in this study was nanopriming. We used colloidal silica nanoparticles (size of 10 nm) as the priming agent and copper (Cu) and barium (Ba) as the model heavy metals. This treatment was implemented for tomato (S. lycopersicum var. Momotaro) seed germination. The results showed that the presence of heavy metals during germination may lead to prolonging the germination time. The presence of Cu and Ba at 1 ppm could increase germination time by 28.38% and 26.9%, respectively, compared to control. When primed seeds were subjected to heavy metal stress, the use of silica nanopriming could reduce the germination time by 10.45% for Cu and 11.54% for Ba compared to the unprimed seeds. This evidence demonstrated that nanopriming could make seeds more resilient to heavy metal stress. We also found that heavy metal ions became less detectable in the seedlings when nanopriming was applied. This ion transport alteration essentially allowed seeds to cope with heavy metal stress. This method can be potentially used on various kinds of crops and heavy metals.

Enhanced adaptation to salinity stress in lentil seedlings through the use of trehalose-functionalized silica nanoparticles (TSiNPs): Exploring silica-sugar absorption and oxidative balance

Silica nanoparticles (SiNPs) confer better growth and development of plants under salinity stress. Moreover, the surface-functionalization of SiNPs with bioactive molecules is expected to enhance its efficacy. The present study thus aimed to modify the surface of SiNPs, by attaching a bioactive molecule (trehalose) to obtain TSiNPs. The successful surface functionalization was confirmed using FTIR, XRD, and EDS. The spherical shape and amorphous nature of the nanoparticles were confirmed using SEM. The TEM image analysis revealed that the size of SiNPs and TSiNPs ranged between 20-50 nm and 200–250 nm, respectively. A novel bioassay experiment designed to study the release of silica and trehalose from nanoparticles elucidated that the TSiNPs improved the release and uptake of silica. Also, trehalose uptake significantly improved after 72 h of application due to enhanced release of trehalose from TSiNPs. Further, this study also aimed to investigate the potential benefits of SiNPs and TSiNPs in promoting the growth and development of plants under salinity stress. In this context, the nanoparticles were applied to the saline-stressed (0, 200, 300 mM) lentil seedlings for the in-planta experiments. The results revealed that both SiNPs and TSiNPs improved the growth of seedlings (shoot, and root length), ionic balance (K+/Na+ ratio), and osmolyte status (sugars, proline, glycine betaine, trehalose). Additionally, increased antioxidant enzyme activities helped scavenge ROS (H2O2, O2.-) generated in NaCl-stressed seedlings, ultimately improving the membrane integrity (by reducing MDA and EL). However, the TSiNPs exhibited a much-enhanced activity in stress alleviation compared to the SiNPs.

Human lung cell cytotoxicity of antibacterial-loaded silica nanoparticles

Silica nanoparticles (SiNPs) are extensively used in multiple biomedical and drug delivery applications. We synthesized, characterized, and assessed the role of SiNP size in several human cell types. SiNPs of different sizes (60 nm, 100 nm, and 300 nm) were synthesized via the Stöber method and their surface was modified by the grafting of ligands (-OH bare, –NH2 amino, and –SH thiol) using organosilane chemistry. SiNPs size, dispersity, and surface were determined by scattering electron microscopy (SEM), hydrodynamic diameter by dynamic light scattering (DLS), and surface grafting by Fourier-transform infrared spectroscopy (FT-IR). Results show no evident cytotoxicity in the tested concentrations and time-courses, up to 30 ppm and 72 h on human cervical (HeLA), lung (A549) and glioblastoma (U251) cells. Fluorescent; rhodamine-labeled SiNPs grafted with positively charged groups were taken up more at greater amounts than unfunctionalized-SiNPs. Rifampicin and vancomycin loading was suitable only in thiolated-SiNPs. SiNPs loaded with rifampicin released the drug and were active against Staphylococcus aureus cultures in a concentration-dependent manner, suggesting that SiNPs could be used for bacterial infections treatment where the localized antibiotic release is desired.

Silica Nanoparticle Size Determines the Mechanisms Underlying the Inhibition of Iron Oxide Nanoparticle Uptake by Daphnia magna.

Aquatic environments are complicated systems that contain different types of nanoparticles (NPs). Nevertheless, recent studies of NP toxicity, and especially those that have focused on bioaccumulation have mostly investigated only a single type of NPs. Assessments of the environmental risks of NPs that do not consider co-exposure regimes may lead to inaccurate conclusions and ineffective environmental regulation. Thus, the present study examined the effects of differently sized silica NPs (SiO2 NPs) on the uptake of iron oxide NPs (Fe2O3 NPs) by the zooplankton Daphnia magna. Both SiO2 NPs and Fe2O3 NPs were well dispersed in the experimental medium without significant heteroaggregation. Although all three sizes of SiO2 NPs inhibited the uptake of Fe2O3 NPs, the underlying mechanisms differed. SiO2 NPs smaller than the average mesh size (∼200 nm) of the filtering apparatus of D. magna reduced the accumulation of Fe2O3 NPs through uptake competition, whereas larger SiO2 NPs inhibited the uptake of Fe2O3 NPs mainly by reducing the water filtration rate of the daphnids. Overall, in evaluations of the risks of NPs in the natural environment, the different mechanisms underlying the effects of NPs of different sizes on the uptake of dissimilar NPs should be considered.

Grafting tetradecyl methacrylate-carbic anhydride (CA) or tetradecyl methacrylate-tetrahydrophthalic anhydride (THPA) co-polymers onto surface-modified nano silica to develop of pour point depressants for diesel

Polymers with alkyl methacrylate as structural unit can significantly improve cold flow properties of diesel. Grafting polymers onto surface-modified nanomaterials can further enhance the low temperature fluidity of diesel. In this study, two molecules containing the structure of dicarboxylic anhydride were used as structural unit with tetradecyl methacrylate to synthesise the polymer pour point depressant (PPD). These polymer PPDs achieved excellent depressive effects, in particular, 1500 ppm of tetradecyl methacrylate–carbic anhydride (9:1) reduced the cold filter plugging point (CFPP) and solid point (SP) of diesel by 8 and 18 ℃, respectively. To further enhance the low-temperature fluidity properties of diesel, silane coupling agents were used to surface-modify nano silica, and then polymers were chemically grafted onto the surface-modified nano silica to prepare the nano PPDs. The well-dispersed nano PDDs achieved higher depressive effects than polymer PPDs on diesel. The diesel treated with 1500 ppm of tetradecyl methacrylate–carbic anhydride–surface modified nano silica (9:1:1) showed a decrease in CFPP and SP of 14 ℃ and 21 ℃, respectively. Transmission electron microscope was used to characterise the morphology and particle size of nano silica before and after surface modification and chemical grafting. The structural features of polymer PPDs and nano PPDs were analysed using fourier transform infrared spectroscopy, gel permeation chromatography and proton nuclear magnetic resonance. Finally, the n-alkane crystallisation habit and wax crystal growth habit of pure diesel and diesel treated with polymer and nano PPDs during cooling process were characterized using differential scanning calorimetry, polarising optical microscopy and rheometry. The effects of polymer and nano PPDs on the nucleation and growth patterns of n-alkanes in diesel were presented and the possible mechanism was inferred.

Simple preparation of silicone rubber Pickering emulsions using silica nanoparticles for water-borne thermal protection coating

Abstract In this study, we aimed to develop stable silicone rubber Pickering emulsions by employing silica nanoparticles as stabilizers in order to produce a water-borne thermal protection coating. Initially, silica nanoparticles were synthesized using the Stöber method and subsequently functionalized with γ-glycidoxypropyltrimethoxysilane (GTMS). The size and grafting efficiency of the GTMS-modified silica nanoparticles were characterized using transmission electron microscopy and thermogravimetric analysis, respectively. Furthermore, the functionalization mechanism was elucidated by monitoring the pH and Zeta potential of the silica sols. Subsequently, the silicone rubber Pickering emulsion was prepared via the emulsion inversion point method and characterized using transmission electron microscopy. The emulsification process was analyzed by measuring the conductivity of the emulsion during the phase transition. Finally, the water-borne coating was formulated by blending the emulsions with Kaolin, glass fiber, and glass microspheres. The thermal protection performance of the resulting coating was evaluated under typical test conditions, with the highest heat flow reaching 242 kW m−2 for 40 s.

Recovery of Chlorosilane Residual Liquid to Prepare Nano-Silica via the Reverse Micro-Emulsion Process.

In this paper, nano-silica particles were prepared from chlorosilane residue liquid using an inverse micro-emulsions system formed from octylphenyl polyoxyethylene ether (TX-100)/n-hexanol/cyclohexane/ammonia. The influence of different reaction conditions on the morphology, particle size, and dispersion of nano-silica particles was investigated via single-factor analysis. When the concentration of chlorosilane residue liquid (0.08 mol/L), hydrophile-lipophilic-balance (HLB) values (10.50), and the concentration of ammonia (0.58 mol/L) were under suitable conditions, the nano-silica particles had a more uniform morphology, smaller particle size, and better dispersion, while the size of the nano-silica particles gradually increased with the increase in the molar ratio of water to surfactant (ω). The prepared nano-silica was characterized through XRD, FT-IR, N2 adsorption/desorption experiments, and TG-DSC analysis. The results showed that the prepared nano-silica was amorphous mesoporous silica, and that the BET specific surface area was 850.5 m2/g. It also had good thermal stability. When the temperature exceeded 1140 °C, the nano-silica underwent a phase transition from an amorphous form to crystalline. This method not only promoted the sustainable development of the polysilicon industry, it also provided new ideas for the protection of the ecological environment, the preparation of environmental functional materials, and the recycling of resources and energy.