Synthesis and structural reactivity of inorganic–organic hybrid nanocomposites – A review

Sustainability in the green engineering of nanocomposites based on marine-derived polysaccharides and collagens: A review

Nanocomposites are sophisticated materials that incorporate nanostructures into matrix materials, such as polymers, ceramics and metals. Generally, the marine ecosystem exhibits severe variability in terms of light, temperature, pressure, and nutrient status, forcing the marine organisms to develop variable, complex and unique chemical structures to boost their competitiveness and chances of survival. Polymers sourced from marine creatures, such as chitin, chitosan, alginate, sugars, proteins, and collagen play a crucial role in the bioengineering field, contributing significantly to the development of nanostructures like nanoparticles, nanocomposites, nanotubes, quantum dots, etc. These nanostructures offer a wide array of features involving mechanical strength, thermal stability, electrical conductivity, barrier and optical characteristics compared to traditional composites. Notably, marine nanocomposites have distinctive roles in a wide spectrum of applications, among them anti-cancer, anti-microbial, antioxidant, cytotoxic, food packing, tissue engineering and catalytic actions. Sol-gel, hot pressing, chemical vapor deposition, catalytic decomposition, dispersion, melt intercalation, in situ intercalative polymerization, high-energy ball milling and template synthesis are common processes utilized in engineering nanocomposites. According to our literature survey and the Web of Science, chitosan, followed by cellulose, chitin and MAPs emerge as the most significant marine polymers utilized in the construction of nanocomposites. Taken together, the current manuscript underscores the biogenesis of nanocomposites, employing marine polymers using eco-friendly processes. Furthermore, significant emphasis in this area is needed to fully explore their capabilities and potential benefits. To the best of our knowledge, this manuscript stands as the first comprehensive review that discusses the role of marine-derived polymers in engineering nanocomposites for various applications.

Silica-Supported Styrene-Co-Divinylbenzene Pickering Emulsion Polymerization: Tuning Surface Charge and Hydrophobicity by pH and Co-Aid Adsorption

In this work, polymerizations of styrene (St) in the presence of divinylbenzene (DVB) as a crosslinking agent and sodium 4-vinylbenzenesulfonate (VBS) have been performed in Pickering emulsions, using silica nanoparticles (SNps) as stabilizing agents and ammonium persulfate as a hydrophilic initiator. In oil-in-water Pickering emulsions with alkaline continuous phase (pH = 9) at 1, 2, and 3 wt% DVB (relative to St), polydisperse spheroid copolymer submicronic nanoparticles were obtained. Comparatively, polymerizations performed in Pickering emulsions with acidic continuous phase (pH = 5) allowed preparing St-co-DVB microspheres with core–shell structures at 1 wt% DVB and St-co-DVB hybrid monoliths with bi-continuous morphologies at 2 and 3 wt% DVB. It is noteworthy that this work reports Pickering emulsion polymerization as a new strategy for preparing hybrid percolated scaffolds with bi-continuous porosity. The proposed mechanisms originated by pH, DVB, and VBS and the drastic impact caused on the final morphology obtained, either hybrid particles or monoliths, are discussed herein.

Porous solid carbon source-supported denitrification in simulated mariculture wastewater

A porous solid carbon source was prepared by semen litchi (SL), poly(vinyl alcohol) (PVA) and sodium alginate (SA) in aqueous. The effect of SL content on the structures and denitrification performance of the porous solid carbon source in simulated mariculture wastewater was investigated. The SL/PVA/SA beads showed a network structure with a wide range of macropores. Compared with blank beads, the SL/PVA/SA beads showed an increased rough surface and whole distribution on the surface with the increase of SL. In addition, SL/PVA/SA beads have more uniform pore size, but the porosity of SL/PVA/SA beads was decreased with the increase of SL. The porosity of the beads was 83.24%, 74.24%, 71.48% and 71.29% for blank beads and SL/PVA/SA beads contained 30%, 40% and 50% SL, when it was used as a solid carbon source for denitrification. Owing to their good porosity and biocompatibility, SL/PVA/SA beads had shorter acclimation time. Nitrate removal rate could reach up to 100% after two days of adaptation. After the exhaustion of carbon sources, nitrate removal rate less than 50% occurred at the 9th, 10th and 11th day for SL/PVA/SA beads that contained 30%, 40% and 50% SL, respectively. The beads that contained 50% SL exhibited longer lifetime during the denitrification reaction and denitrification rate could reach 243.5 ± 7.08 mg N (L d)^-1. It could be used as an economical and effective carbon source for denitrification in mariculture wastewater.

Role of Sintering Temperature in Production of Nepheline Ceramics-Based Geopolymer with Addition of Ultra-High Molecular Weight Polyethylene

The primary motivation of developing ceramic materials using geopolymer method is to minimize the reliance on high sintering temperatures. The ultra-high molecular weight polyethylene (UHMWPE) was added as binder and reinforces the nepheline ceramics based geopolymer. The samples were sintered at 900 °C, 1000 °C, 1100 °C, and 1200 °C to elucidate the influence of sintering on the physical and microstructural properties. The results indicated that a maximum flexural strength of 92 MPa is attainable once the samples are used to be sintered at 1200 °C. It was also determined that the density, porosity, volumetric shrinkage, and water absorption of the samples also affected by the sintering due to the change of microstructure and crystallinity. The IR spectra reveal that the band at around 1400 cm⁻¹ becomes weak, indicating that sodium carbonate decomposed and began to react with the silica and alumina released from gels to form nepheline phases. The sintering process influence in the development of the final microstructure thus improving the properties of the ceramic materials.

Synthesis and Gas Transport Properties of Poly(2,6-dimethyl-1,4-phenylene oxide)⁻Silica Nanocomposite Membranes

The emulsion polymerized mixed matrix (EPMM) method is a new approach to prepare nanocomposite membranes, in which inorganic nanoparticles are synthesized in situ at the interface of a dispersed aqueous phase in a continuous phase of polymer solution. In this paper, we report the synthesis and characterization of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based EPMM membranes, in which silica nanoparticles are synthesized by the polymerization of tetraethylorthosilicate (TEOS) in the presence of two different co-solvents, ethanol and acetone, which are soluble in both the aqueous phase and the polymer solution. The EPPM membranes prepared in the presence of acetone show greater conversions of TEOS and a different structure of the synthesized silica nanoparticles compared to the EPMM membranes prepared in the presence of ethanol. The former membranes are both more permeable and more selective for O₂/N₂ and CO₂/CH₄. Both types of EPMM membranes are more permeable than the reference PPO membranes. However, while their O₂/N₂ selectivity is practically unchanged, their CO₂/CH₄ selectivity is decreased compared to the reference PPO membranes.

Formation and distribution of ZnO nanoparticles and its effect on E. coli in the presence of sepiolite and silica within the chitosan matrix via sonochemistry

In this study, a new bio-nanocomposite was prepared and characterized with a focus on the formation of hexagonal ZnO and orthorhombic zinc silicate (Zn₂SiO₃(OH)₂) phases under ultrasonic irradiation. Chitosan/sepiolite/ZnO and chitosan/silica/ZnO bio-nanocomposites were synthesized using a simple solution method in which extreme physical and chemical conditions created by cavitation within the chitosan solution allowed for the transformation of aqueous Zn(OH)₂ to crystallized ZnO and Zn₂SiO₃(OH)₂ in room temperature. Both the loading of sepiolite and silica with the zinc precursor significantly influenced the morphology and crystalline structure of the product, however, different zinc compounds were observed. Sepiolite was exfoliated, resulting in a fine, even colloidal solution through ultrasonic dispersion. Exfoliation of sepiolite nanofibers led to the homogeneous dispersion of Zinc in the form of Zn(OH)₂ in chitosan matrix. When the same procedure was conducted using the silica component, a formation of ZnO and Zn₂SiO₃(OH)₂ was observed, components that were not observed when the procedure was conducted using sepiolite. The average crystalline size of ZnO was calculated as 36nm for ZnO. In addition, the quantities of crystalline and the ZnO phase volume was determined as 15%. Through zone of inhibition, the silica nanocomposite was discovered to have antibacterial activity. In contrast, the sepiolite compound did not exhibit these properties. We thus hypothesize that HO radicals, formed during ultrasonic irradiation trigger the formation of a silicate ion (SiO₃^2-) and formation of ZnO and Zn₂SiO₃(OH)₂ species in chitosan/silica/ZnO bio-nanocomposite, which causes to exhibit these antibacterial properties against Gram-negative E. coli. Chemical characterization and dispersion of the structure of the ZnO and Zn₂SiO₃(OH)₂ phases were done using X-ray diffraction (XRD) and scanning electron microscopy techniques (SEM) with EDAX and X-ray photoelectron spectroscopy (XPS).

High performance anti-corrosive epoxy–titania hybrid nanocomposite coatings

Mechanical stability, surface hydrophobicity, and thermal stability of anticorrosive polymeric coatings play a significant role in technological and industrial fields.

POLYVINYL BUTYRAL (PVB), VERSETILE TEMPLATE FOR DESIGNING NANOCOMPOSITE/COMPOSITE MATERIALS:A REVIEW

In current article, the versatile behaviour of Polyvinylbutyral (PVB)and its ability to form composite materials withvarious inorganic species is reported. PVB has hydrophilic vinyl alcohol groups and hydrophobic vinyl butyral groups. These groups behave as promoters of polymer adhesive and binders for organic moieties. The composite materials of PVB have been synthesized viaphysical as well as chemical both protocols. PVB is used as a constituent part in the formation of composite, induces a specific property in a resulting one which are utilized by various ways since it has stronger in binding ability, sharper optical clarity and able for providing flexibility and toughness in the formed composite. Varioussophisticated instrumentation techniques eg FTIR, XRD, FESEM, TEM etc. are reported for characterizations of samples. The composite materials have excellent film formation properties, and can be potential candidate for photoelectric as well as photovoltaic applications. The inorganic conducting species which do not have film formation ability can be useful by composite formation along with PVB. The green protocols for synthesis of composites may also useful for biological applications.