Structure Of Silica Nanoparticles Research Articles

Mitigating CO2 emanations within the marine concrete industry with different structures of silica nanoparticles

The extensive utilization of marine concrete results in a significant consumption of cement, thereby leading to an increase in CO2 emanations. Enhancing the potency and longevity of marine concrete serves as an efficacious approach to mitigate CO2 emanations. The objective of this investigation was to introduce colloidal silica nanoparticles with distinct three-dimensional structures (MCM-41, SBA-15, and DFNS) for the purpose of enhancing the mechanical functionality and longevity of remarkable sulfate persistence Portland cement. Meantime, the incorporation of silica nanoparticles with distinct three-dimensional architectures (DFNS, MCM-41, and SBA-15) into marine cement mortar was carried out, and an investigation was conducted on the aggregation of silica nanoparticles, as well as the humidifying process and micro-process of the mortar. According to the findings, the addition of silica NPs improved the resilience, mechanical traits, and longevity of the marine cement cases. When the inclusion of silica nanoparticles with varying three-dimensional structures (DFNS, MCM-41, and SBA-15) was implemented, a decrease in both the chloride diffusion coefficient and porosity was observed. The compressive intensity of cement mortar was enhanced in the presence of DFNS, MCM-41, and SBA-15 when compared to control samples, following a rehabilitating period of 5, 15, and 30 days. These advancements in intensity and longevity suggest that DFNS exhibits considerable potential in mitigating CO2 emanations within the marine concrete industry.

Preparation of Hollow Silica Nanoparticles Using Fluorinated Surfactant and Fluorocarbon Solvents

In this study, we used a new class of fluorinated surfactant as a soft template for the preparation of the hollow silica nanoparticles. The size of the hollow silica nanoparticles was enlarged by incorporating a variety of swelling agents (perfluorodecalin, perfluorotributylamine, perfluorooctane, and perfluorooctyl bromide) into the cores of the micelles of the fluorinated surfactant. However, once we used the perfluorinated acids (perfluorooctadecanoic acid and perfluorodecanoic acid) as swelling agents, the structure of silica nanoparticles is solid without the formation of hollow voids. The TEM analysis combined with copper elemental mapping of the hollow silica loaded with copper hexadecafluorophthalocyanine indicated that the cores of the hollow silica nanoparticles are hydrophobic. The formation mechanism of the hollow silica nanoparticles is similar to that prepared by hydrocarbon surfactant/hydrocarbon, which was supported by the zeta potential measurements. The prepared hollow silica nanoparticles had the type IV isotherm with the H3 hysteresis loop.

A veil-over-sprout micro-nano PMMA/SiO2 superhydrophobic coating with impressive abrasion, icing, and corrosion resistance

Superhydrophobic (SHP) coatings have been reported with many promising applications using various nano-micro structures with surfactants of low surface energies. However, many SHP coatings have poor durability, largely limiting their practical importance. In this study, a durable SHP coating is demonstrated with a novel veil-over-sprout micro-nano structure of silica nano particles (SNP) and poly(methyl methacrylate) (PMMA). This coating displays a large water contact angle (WCA) of 168.0° and a small sliding angle (SA) of less than 1.0°. Excellent abrasion resistance is demonstrated with excellent superhydrophobicity (WCA = 159.0°) after consecutive tests with sandpaper, high-density water flow and fine sand impact. An excellent self-healing function has been achieved with this SHP coating after stored at room temperature, recovering its remarkable superhydrophobicity. Outstanding resistance against ice formation is exhibited with the starting-freezing time at −20 ℃ three times longer than uncoated surface. Strong resistance to acid and base attacks is observed even after a week of immersion in highly acidic and alkaline environments (pH 1.0–14.0), without much degradation of SHP performance. Efficiency of up to 99.9% is demonstrated in corrosion protection in a solution with pH = 10.0 to extend the life of the metal. In addition, remarkable SHP durability is demonstrated after long-term outdoor exposure. Therefore, this work has shown off a promising methods for SHP coatings towards future practical applications.

Poly(N‐vinyl imidazole) grafted silica nanofillers: Synthesis by RAFT polymerization and nanocomposites with polybenzimidazole

ABSTRACTIn this report, we synthesized poly(N‐vinyl imidazole) (PNVI) grafted silica nanoparticles (SiNP) by using RAFT polymerization through grafting‐from approach to demonstrate that the self‐assembled structure of SiNP is the key diving force in improving physical properties of SiNP based nanocomposites. In a multistep synthetic process, well‐defined PNVI chains with tunable molecular weights and surface chain densities were grown from the RAFT agent anchored SiNP surface using N‐vinyl imidazole (NVI) as a monomer. Spectroscopic and thermal analysis confirmed surface grafting of PNVI on SiNP surface and the amount of grafted PNVI chins were also quantified. The mean diameter of the PNVI grafted SiNP (PNVI‐g‐SiNP) particles altered between 50 and 100 nm with the variation of PNVI chain lengths. The present approach is metal‐catalyst free, straight forward, and provides PNVI functionalized SiNP in a simple manner in comparison to the reported methods. Further, these PNVI‐g‐SiNP particles were used as a nanofiller to prepare nanocomposites with Poly(4,4′‐diphenylether‐5,5′‐bibenzimidazole) (OPBI). These nanocomposites displayed significantly higher mechanical, proton conductivity and less acid leaching properties than the pristine OPBI. The anisotropic self‐assembled ordered structure formation of nanofillers in the nanocomposites believed to be the driving force for the enhanced physical properties. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 365–375

Fusion of Porous Isotactic Poly(methyl methacrylate) Thin Films Fabricated on Silica Nanoparticles with Stepwise Stereocomplex Assembly

Structures of silica nanoparticles coated with stereocomplex thin films composed of isotactic (it) poly(methyl methacrylate) (PMMA) and syndiotactic (st) poly(methacrylic acid) (PMAA) and with porous it-PMMA thin films under gentle stirring or static conditions were analyzed by dynamic light scattering (DLS) and scanning electron microscopy (SEM), respectively. The porous it-PMMA films were fabricated by stepwise stereocomplex assembling of it-PMMA and st-PMAA, and subsequent extraction of the st-PMAA from the films. From DLS results, an evident difference was not observed between the it-PMMA films and the stereocomplex films, whereas the it-PMMA films after 10 h of stirring in acetonitrile/water (4/6, v/v) and drying on a SEM stage fused to form nanostructured networks. The fusion of the it-PMMA films on the silica nanoparticles occurred not by the dissolution of it-PMMA in the mixed solvent, but rather by an interaction of the it-PMMA chains driven by the slight solvation of acetonitrile without dissolution. Thus, leaving the solution at rest would be important for film fusion on the particles, and multiple spherical substrates could promote the crosslinking of the it-PMMA chains on the particles.