A convenient strategy to functionalize carbon nanotubes with ascorbic acid and its effect on the physical and thermomechanical properties of poly(amide–imide) composites

Carboxymethyl cellulose@multi wall carbon nanotubes functionalized with Ugi reaction as a new curcumin carrier

In recent years, the fabrication of new drug delivery systems (DDSs) based on functionalization by multi-component reactions (MCRs) has received special attention. In this regard, to obtain a new oral administration system for colon-specific cancer treatment, the CMC@MWCNTs@FCA carrier was designed and prepared from the functionalization of the CMC@MWCNTs as a biocompatible raw material with carboxamide group by the Ugi reaction. FT-IR analysis confirmed the successful synthesis of the product through the change in the functional groups of reagents. Additionally, the crystalline structure and porosity of the samples were studied by XRD and BET techniques. After a detailed characterization, the curcumin (CUR) was loaded on CMC@MWCNTs and CMC@MWCNTs@FCA, respectively, about 29 % and 38 %. In vitro drug release behavior studies for CUR-loaded CMC@MWCNTs@FCA showed the controlled release for it, so 11.6 % and 76.5 % of CUR, respectively were released at pH 1.2 and pH 7.4. Toxicological analysis displayed the IC₅₀ of CMC@MWCNTs@FCA@CUR is 752 μg/mL. In conclusion, the obtained findings display that the fabricated system can be proposed as a biocompatible carrier for specific colon cancer treatment.

Green synthesis of nano-Al2O3, recent functionalization, and fabrication of synthetic or natural polymer nanocomposites: various technological applications

Environmentally friendly fabrication of nano-Al₂O₃, recent functionalization, and preparation of polymer nanocomposites including natural and man-made polymers with various industrial applications are reviewed.

A functionalized carbon nanotube nanohybrids-based QuEChERS method for detection of pesticide residues in vegetables and fruits

A self-separating, analyte-compatible, and efficient clean-up method for QuEChERS extracts was designed and developed based on dispersive solid-phase extraction using a branched polyethylenimine and nanoscale CaSO₄ functionalized carboxylated multi-walled carbon nanotubes (MWCNTs) nanohybrids as sorbent. The feasibility of using a self-separating strategy based on the functionalization of sorbent in a purification procedure was analyzed for the first time in this study. Compared to the traditional QuEChERS method, the proposed method is rapid and convenient without centrifugation of numerous samples in the clean-up process. The use of nanohybrids overcame the issue of low recoveries for planar pesticides, which are easily adsorbed using MWCNTs. A better clean-up capability of the nanohybrids to remove matrix interferences and reduce matrix effect was demonstrated compared with that of traditional clean-up sorbent primary secondary amine. The method was validated by determining twenty-eight pesticides in cucumber, cabbage, apple, and orange. Limits of detections were in the range of 0.0001-0.0026 mg/kg. Spike recoveries of pesticides were within 75.3 - 113.6%, with relative standard deviations less than 14.3% at levels 0.01 mg/kg and 0.1 mg/kg. The developed method was successfully applied to monitor the multi-residues.

Microwave and ultrasound-assisted synthesis of poly(vinyl chloride)/riboflavin modified MWCNTs: Examination of thermal, mechanical and morphology properties

This study focused on the preparation and investigation of physicochemical features of new poly(vinyl chloride) (PVC) nanocomposites (NCs) including different amounts of carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) functionalized with riboflavin (RIB). Firstly, to increase the hydrophilicity of MWCNTs, the surface of them was functionalized by incorporating and formation of ester groups with RIB as a low cost and environmentally friendly biomolecule through ultrasound and microwave irradiations. Afterwards, PVC/RIB-MWCNTs NCs were fabricated via the solution casting and ultrasonic dispersion methods. Prepared NCs were examined by X-ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, transmission electron micrograph, and Raman spectroscopy. The PVC/RIB-MWCNTs NCs (12wt%) showed the higher mechanical and thermal behavior as compared to other concentration of MWCNTs.

Application of ultrasonic irradiation as a benign method for production of glycerol plasticized-starch/ascorbic acid functionalized MWCNTs nanocomposites: Investigation of methylene blue adsorption and electrical properties

A solution mixing and ultrasonic dispersion method as a green, the fast, inexpensive and effective technique was utilized to prepare glycerol plasticized-starch (GPS)/ascorbic acid (AA)-MWCNTs nanocomposites (NCs) via the introduction of various amounts of AA-MWCNTs (3, 6 and 9wt%) as filler into GPS matrix. The GPS was synthesized by addition of glycerol (50%) as a plasticizer to starch which enhances its flexibility. Characterization of the obtained GPS/AA-MWCNTs NCs was accomplished by different techniques. The optimum filler content for the generation of fine electrical conductivity and good mechanical properties was found to be about 3wt%. The distribution of AA-MWCNTs at the low content (3wt%) in the GPS matrix was better due to the strong linkage between nanofiller and GPS in GPS/AA-MWCNTs NC. The results of adsorption studies showed that the fabricated NC can be a good adsorbent for removal of methylene blue (MB) dye from aqueous solutions.

Sonochemical assisted synthesis and characterization of magnetic PET/Fe3O4, CA, AS nanocomposites: Morphology and physiochemical properties

Ultrasonic-assisted synthesized iron oxide (Fe₃O₄) nanoparticles (NP)s were modified with biodegradable citric acid (CA) and ascorbic acid (AS) [vitamin C] as capping agents. The ultrasonication (US) was applied for the synthesis and modification process as an easy, safe and fast method. Dissolution/reprecipitation procedure was offered to recycle poly(ethylene terephthalate) (PET) bottles and then, it has been focused on the preparation of PET nanocomposites (NC)s based on solution method via sonication agitation to disperse the Fe₃O₄, CA, AS NPs in the organic polymeric surrounding substance. Magnetic PET NCs with modified Fe₃O₄ NPs loading (1, 3, and 5wt%) were fully characterized and the effect of NPs was examined by focusing on four aspects: Fourier transform infrared spectroscopy, X-ray diffraction, thermal stability studies, field emission scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. Also, flame retardant behaviors of the NCs were investigated. Achieved morphology pictures displayed the presence of well dispersed magnetic NPs in the polymer matrix at nano-scale. In this work after recycling of PET waste bottles, it was aim to have magnetic PET due to its various potential applications such as wastewater treatment, catalysts, biomedicine and drug delivery system and electromagnetic devises. It was also intention to show easy, time saving and safe way (US method) to have magnetic PET which was achieved. From the results it can be concluded that one can readily have good dispersion of magnetic NPs in the PET matrix.

Surface functionalization of carbon nanotubes: fabrication and applications

This review highlights recent development in functionalization of CNTs and their applications.

The fabrication and characterization of nanocomposites containing new poly(amide–imide) based on 4,4-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) and carboxylic acid-functionalized multiwalled carbon nanotubes

In this article, a nanostructure poly(amide–imide) (PAI) was prepared from the polymerization of 4,4′-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) with 3,5-diamino- N-(4-hydroxyphenyl)benzamide using tetra- n-butylammonium bromide as a green media and triphenylphosphite as a condensing agent. This methodology is safe and green since toxic and volatile organic solvents were eliminated. To obtain a homogeneous dispersion of multiwalled carbon nanotubes (MWCNTs) in the PAI matrix, carboxyl-modified MWCNT (CA-MWCNT) was used. The resulting nanocomposites were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermogravimetric analysis. TEM and FESEM results confirm good dispersion of CA-MWCNTs in the polymer matrix.

Performance evaluation of fructose-functionalized multiwalled carbon nanotubes/biodegradable poly(amide–imide) based on N,N′-(pyromellitoyl)-bis-S-valine bionanocomposite

Carboxyl-modified multiwalled carbon nanotubes (MWCNTs) were functionalized with fructose as a biological active molecule in a green method. Then a simple ultrasonication-assisted solution blending process was used to disperse the fructose-functionalized MWCNTs (f-MWCNTs) into a biodegradable poly(amide–imide) (PAI) efficiently to obtain PAI/f-MWCNT bionanocomposites. The effect of f-MWCNT on thermal and structural properties of PAI was investigated by several techniques, including powder X-ray diffraction, field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis (TGA). The FESEM and TEM results showed that the f-MWCNT wholly separated and uniformly dispersed in the PAI matrix. TGA results showed that thermal stability of the composites was significantly increased with the addition of f-MWCNT compared with the pure PAI.

Influence of biosafe amino acid-functionalized multiwalled carbon nanotubes on the morphology and thermal properties of the poly(amide–imide) nanocomposites containing N,N′-(pyromellitoyl)-bis-S-valine segments

In this study, S-valine-functionalized multiwalled carbon nanotubes (f-MWCNTs)/poly(amide–imide) (PAI) bionanocomposites (BNC)s were prepared by a simple ultrasonication-assisted solution blending process. First, carboxylated MWCNTs were functionalized with S-valine to achieve a fine dispersion of f-MWCNT bundles in the PAI matrix due to hydrogen bonding and π–π stacking interaction between f-MWCNTs and polymer functional groups and aromatic moieties. The existence of S-valine as a biodegradable segment in both f-MWCNTs and optically active PAI provided potentially biodegradable nanocomposites and caused compatibility between f-MWCNTs and the polymer matrix. The obtained BNCs were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The TEM and FESEM images confirmed good dispersion of f-MWCNTs in the polymer matrix. The results of TGA and XRD analysis suggested that a good thermal stability and dispersion occurred especially with low filler amounts (5 wt%) of f-MWCNTs.