Methodologies of Application of Sol-Gel Based Solution onto Substrate: A Review

Just as the diverse as the various substrates that can be coated is the choice of several coating methods by which the coating can be applied to these pretreated surfaces. They include the manual methods, where great skills and experience is needed, on the other hand there are automated and robotics coating control methods where coating can be applied with more precise manner. Sol-gel process is one of the promising bottom up nano-coating technologies to develop thin film over various metallic substrates. The property and characteristic of the resulting film is strongly influenced by the various parameters and reaction conditions of the sol-gel process and of course on the deposition techniques. In this review, we have thrown some lights on different coating application processes covering theoretical principle, advantages, disadvantages, and special various parameters controlling the final film quality

Biomass derived carbon nanoparticle as anodes for high performance sodium and lithium ion batteries

In this paper, we report a flame deposition method to prepare carbon nanoparticles (CNPs) from coconut oil. The CNPs were further modified with a piranha solution to obtain surface-carboxylated carbon nanoparticles (c-CNPs). When used as an anode for sodium-ion batteries, the CNPs and c-CNPs respectively delivered discharge capacities of 277 and 278 mA h g in the second cycle at a current density of 100 mA g. At the 20th cycle, the capacities of CNP and c-CNPs were 217 and 206 mA h g respectively. The results suggest that modification of the CNPs with the piranha solution improved neither the charge storage capacity nor the stability against cycling in a sodium-ion battery. When the CNP and c-CNP were used an anode in a lithium-ion battery, 2nd-cycle discharge capacities of 741 and 742 mA h g respectively at a current density of 100 mA g were obtained. After 20 cycles the capacities of CNP and c-CNP became 464 and 577 mA h g respectively, showing the cycling stability of the CNPs was improved after modification. The excellent cycling performance, high capacity and good rate capability make the present material as highly promising anodes for both sodium-ion and lithium-ion batteries

Structural and optical properties of ionic liquid based hybrid perovskitoid: a combined experimental and theoretical investigation

Herein, we report a novel layered lead bromide, (CH3CH2)3N+Br−(CH2)2NH+3)PbBr3, where bulky organic cations, (CH3CH2)3N+Br−(CH2)2NH+3), amino-ethyl triethyl ammonium [aetriea] were not only incorporated between the inorganic layers but also sandwiched within the inorganic [PbBr6]4− octahedral layered structure. The UV-Visible, photoluminescence spectroscopy (PL), X-ray diffraction (XRD) and a field-emission scanning electron microscope (FE-SEM) result show that the new perovskitoid has a microrod shape with an estimated bandgap of ∼3.05 eV. The structural and optoelectronic properties of the [aetriea]PbBr3perovskitoid were further corroborated by first-principles density functional theory (DFT) calculations. Thermogravimetric analysis (TGA) data show good stability of the [aetriea]PbBr3perovskitoid. Time-resolved photoluminescence (TRPL) decays from new [aetriea]PbBr3perovskitoid showing 6 ns average lifetime. These results suggest that doubly charged cation hybrid perovskite materials are potential candidates for optoelectronic applications

Sol-Gel Chemistry Materials for Anti-Corrosion Coatings

This review paper summarizes the current state of the art of sol-gel technology for formulating anti corrosive protective coating. A brief description of the mechanism of sol-gel reactions, various parameters that influence the property of the final product and the course of the sol-gel reaction has been given. Different types of metal precursors that are extensively used in sol preparation and the advantages and disadvantages have also been mentioned in brief. Surface chemistry of sol-gel matrix and various stabilizing and destabilizing forces that are active on the surface of colloidal particles have also been discussed. Problems related to obtaining good quality product with uniformly distributed concentrations have been outlined. Possible pathways for further improvement of anti-corrosive properties of the coating have been described, such as incorporation of various types of additives into the sol matrix prior to coating. As a whole the present study summarizes the superiority and benefits of organic-inorganic hybrid coatings using sol-gel technique and having good protective and anti-corrosive properties

Recent developments of camphor based carbon nanomaterial: their latent applications and future prospects

Carbon nanomaterials have gained tremendous importance in nanoscience owing to their excellent properties and versatile applications. However, the major concern in using carbon nanomaterial is that they are costly to synthesize and use harmful precursors throughout their synthesis. Therefore, alternative means for the production of carbon nanomaterials using safer and greener sources are being currently investigated. In this viewpoint, camphor has demonstrated potential for the synthesis of new carbon nanomaterials with excellent physico-chemical property and biocompatibility. However the research on camphor based nanomaterials has not received much attention in the scientific community. Apart from traditional carbon nanomaterials like carbon nanotube, graphene and fullerene, camphor has the potential to synthesize new materials like carbon nanoparticles, nano-onions and carbon dots using simpler techniques for potential industrial applications. The present review focuses on the recent developments on camphor based carbon nanomaterials, their latent applications and future prospects

Controllable synthesis of biosourced blue-green fluorescent carbon dots from camphor for the detection of heavy metal ions in water

A robust method for the synthesis of fluorescent carbon dots (C dots) from camphor, which provides an insight into themechanismof C dot formation, is reported. Camphor is a biosourced hydrocarbon, which contains an hexagonal ring arranged like an open book. Burning of camphor leads to the formation of soot, which comprises graphitic domains. The soot when treated with piranha solution disintegrates into smaller domains leading to the formation of C dots with a size distribution of ∼1-4 nm. The C dots obtained were carboxyl terminated which was confirmed from the infrared spectroscopic measurements. The D and G bands at ∼1314 cm and ∼1586 cm, respectively, found using Raman spectroscopy and the peaks at 25.01° found using X-ray di ffraction of C dots confirm the presence of graphitic domains. Photoluminescence studies were carried out which reveal exceptional fluorescence in the as prepared C dots. Interestingly the quantum yield is found to be around 21.16%, which is significantly higher than the values reported in previous papers. The current study deals with the sensing of metal ions. Heavy metal cations such as Cd and Hg were used to check whether they a ffect the fluorescence properties of C dots. It was found that other metal ions like Cu, Fe and Zn also quenched the fluorescence of C dot with a different quenching profile

Graphitic nanoparticles from thermal dissociation of camphor as an effective filler in polymeric coatings

We report an easy synthesis of uniformly-sized water soluble graphitic-carbon nanoparticles (CNP) from the soot obtained by the incineration of camphor. The soot was characterized by X-ray diffraction (XRD) and Raman spectroscopy which reveal the presence of graphitic domains in the obtained nanoparticles. Scanning electron microscope (SEM) images display uniformly sized CNPs of about ∼50 nm. The camphoric soot was then oxidized with a piranha solution to decorate the CNP surface with a carboxyl group. This presence of carboxyl groups was confirmed by the CO stretching at 1720.17 cm in the Fourier transform-infrared spectroscopy. Following the surface treatment, CNPs were reacted with diisocyanate to form amide linkages, which were exploited in the fabrication of CNP-polyurethane hybrid composite material (CNP-PU). Minuscule incorporation (0.1, 0.5 wt%) of CNP into polyurethanes showed a magnificent improvement in the overall thermo-mechanical properties of the CNP-PU as compared to neat polyurethane films. From the XRD analysis of CNP-PU it is evident that incorporation of CNPs enhances the crystallinity of the resultant composite. Proper dispersion of CNPs into the polyurethane matrix was noticeable in the SEM images of the composite

Hyperbranched polyol decorated carbon nanotube by click chemistry for functional polyurethane urea hybrid composites

In the present work we report a facile decoration of multi-walled carbon nanotubes with hyperbranched polyether polyol using copper(i) catalyzed azide-alkyne click reaction in order to create hydroxy terminal groups. This decoration has been designed to improve the dispersibility of CNTs in the polymer matrix. These hydroxy functional decorated CNTs were then dispersed into poly(tetramethylene ether) glycol (PTMG) at different weight percentages to get the hybrid pre-polymers. These pre-polymers were reacted with 1-isocyanato-4-[(4-isocyanatocyclohexyl) methyl] cyclohexane (H -MDI) at a NCO : OH ratio of 1.2 : 1 and cured under atmospheric moisture to get the functional polyurethane-urea-CNT hybrid composites. There has been substantial improvement in the thermal stability, mechanical strength, corrosion resistance and antimicrobial activity of the polyurethane hybrid composites with the increase in carbon nanotube loading in pre-polymers. For example, with 2 wt% loading of carbon nanotubes, the tensile strength of the polyurethane hybrid composite improved from 1.25 N mm to 6.25 N mm; the water contact angle improved from 54° to 108° and also the rate of corrosion reduced from 0.047 mm per year to 0.0019 mm per year. We also observed that these hybrids possess remarkable shape recovery properties. These results demonstrate that the decorated CNTs can be used as high performance additives for improving various properties of polyurethane hybrids in cost effective and eco-friendly ways

Nitrogen rich hyperbranched polyurethane-carbon nanohorn composite: Implications on the development of multifunctional coatings

In the present report, we demonstrate the advantages associated with a multifaceted coating comprising of single-walled carbon nanohorns (SWNH) and hyperbranched polyurethane (HBPU). To synthesize the HBPU, we utilized sebacic acid and triethanolamine as starting materials employing traditional polycondensation reaction; A + B approach. The degree of branching as estimated from NMR was found to be ∼60%, indicating a good branching profile. Prepared nitrogen rich HBPU coatings exhibited good corrosion resistance and adhesion to the substrate. Furthermore, an in situ blend of pyrene and functionalized carbon nanohorns (f-SWNH) were introduced within the HBPU matrix to impart additional properties. The obtained HBPU-SWNH composites (CNH-PU) exhibited superior storage modulus (∼1081 MPa), lower corrosion rate (6.16 × 10 mm/year), excellent flexibility, and exceptional thermo-mechanical properties along with fluorescence (due to pyrene moiety). The properties displayed by the composite coatings were much higher as compared to the HBPU in the absence of synergism

Bulk synthesis of green carbon nanomaterials from Desmostachya bipinnata for the development of functional polyurethane hybrid coatings

Carbon nanomaterials have been the focal point of intense study in the past few decades owing to its molecularly defined structure, high aspect ratio and extortionate electrical, mechanical and physical properties. In the present study, we report an easy synthesis of carbon nanomaterials from the grass Desmostachya bipinnata. Fresh grass was collected and dried completely under the sun and was subjected to complete incineration in atmospheric oxygen. Scanning electron microscope image reveal the presenceof carbon micro- and nanorods in the ash of the burnt grass. Then the ash was treated with piranha solutionto obtain carboxyl group on the surface. The surface treatment of the obtained ash was confirmed by infrared spectroscopy and by thermogravimetric analysis. Following the acid treatment, the obtained carboxyl terminated carbon nanomaterials were then reacted with diisocyanate to form amide linkages,which was utilized in the formation of polyurethane films. Minuscle incorporation of ash containing carbon nanomaterial was found to enormously increase the physico-chemical properties of the obtained polyurethane nanocomposite. As compared to the neat polyurethane, the composite material showed a substantial increase in the thermal and mechanical properties