Microfibrous Chitosan−Sepiolite Nanocomposites

Nanoscale Research Letters, 2015

A hybrid nanocomposite material has been obtained by in situ formation of an inorganic network in the presence of a preformed organic polymer. Chitosan biopolymer and tetraethoxysilane (TEOS), which is the most common silica precursor, were used for the sol-gel reaction. The obtained composite chitosan-silica material has been characterized by physicochemical methods such as differential thermal analyses (DTA); carbon, hydrogen, and nitrogen (CHN) elemental analysis; nitrogen adsorption/desorption isotherms, scanning electron microscopy (SEM); and Fourier transform infrared (FTIR) spectroscopy to determine possible interactions between silica and chitosan macromolecules. Adsorption of microquantities of V(V), Mo(VI), and Cr(VI) oxoanions from the aqueous solutions by the obtained composite has been studied in comparison with the chitosan beads, previously crosslinked with glutaraldehyde. The adsorption capacity and kinetic sorption characteristics of the composite material were estimated.

Indonesian Journal of Chemistry, 2015

Montmorillonite was functionalized by (3-glycidyloxypropyl) trimethoxy silane (GPTMS). Subsequently, chitosan (CS) membranes filled by GPTMS-modified montmorillonite particles were prepared and characterized by FTIR. The result of FTIR obtained the peak wavenumber of 2940, 1471 and 1390 cm-1 referring to vibration stretching of CH2, bending of CH2 and CH3 form epoxy groups in silane, respectively which indicated modification of montmorillonite by silane. Compared with the pure CS and CS/PWA-MMT membrane, these CS/PWA-MMT/Silane hybrid membranes show apparently high proton conductivity and the lower methanol permeability, which could be assigned to the better interfacial morphology and compatibility between chitosan matrix and GPTMS-modified montmorillonite. In all the prepared CS/PWA-MMT/Silane hybrid membranes, the CS membrane filled by 10% GPTMS-modified montmorillonite particles exhibits the highest proton conductivity and the lowest methanol permeability, which is 19.15 x 10-3 S...

Colloid and Polymer Science, 2009

Submicron fibers of the composite of poly(vinyl alcohol) (PVA), chitosan oligosaccharide [COS, (1→4)2amino-2-deoxy-β-D-glucose], and montmorillonite clay (MMT) were prepared using electrospinning method with aqueous solutions. Scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal gravimetric analyzer, and tensile strength testing machine (Zwick) were utilized to characterize the PVA/ COS/MMT nanofiber mats morphology and properties. The PVA/COS ratio and MMT concentration play important roles in nanofiber mat properties. XRD and TEM data demonstrated that exfoliated MMT layers were welldistributed within nanofiber. It was also found that the mechanical property and thermal stability were increased with COS and MMT contents.

In the current study the effect of dilution of chitosan acetate solution and of the use of a reflux-solution method on the morphology, the mechanical and water barrier properties of chitosan based nanocomposites is being investigated. Two series of nanocomposite films from two chitosan acetate solutions with 2 w/v% and 1 w/v% in chitosan were prepared, with 3, 5 and 10 wt% Na-montmorillonite (NaMMT) and/or 30 wt% glycerol. Intercalation of NaMMT was more effective in films based on 2 w/v% solutions which presented decreased hydrated crystallinity. Upon NaMMT addition an enhancement was found in stiffness and strength (up to 100%) and a remarkable decrease in the elongation at break (up to 75%) and water vapor permeability (WVP) (up to 65%). This enhancement was less pronounced in 1 w/v% systems. Addition of glycerol had a negative effect on the stiffness, strength and WVP, and a positive effect on the elongation at break and the absorbed water. Compared with the conventional solution cast method, the reflux treatment led to a significant improvement of the tested properties of nanocomposite films.

Solid State Phenomena, 2009

Characterization of chitosan / layered silicate nanocomposites obtained by solutionmixing technique, having different compositions including treated and untreated montmorilonite (MMT) has been performed. The optimum amount of MMT and also the effect of nanoparticles type on nanocomposite properties by DSC, X-ray diffraction and TG measurements have been established. The chitosan chains were inserted into silicate layers to form the intercalated nanocomposites. The interlayer distance of the silicates in the nanocomposites enlarged as their amount increased. The stiffness and thermal stability enhanced.

Progress in Natural Science: Materials International, 2012

Chitosan-montmorillonite is a modified montmorillonite in which the sodium ions in montmorillonite layers are replaced by biopolymeric chitosan. The effects of characteristics of chitosan (i.e. molecular weight and degree of deacetylation) and the chitosan/montmorillonite mass ratio on the properties of chitosan-montmorillonite were investigated. Thermogravimetric analysis, zeta potential and X-ray diffraction results confirmed intercalation of chitosan into montmorillonite layers. An interaction between chitosan and montmorillonite was revealed by FTIR and the zeta potential. The amount of chitosan intercalated into the montmorillonite layers depended on the characteristics of chitosan, with the largest amounts of intercalated chitosan achieved by addition of chitosan with a molecular weight of 71,000 g/mol or a degree of deacetylation of 80% at a fixed chitosan/montmorillonite mass ratio of 2:1. The resulting chitosan-montmorilllonite had good adsorbent properties, especially for adsorption of cationic dyes, and also inhibited E. coli by almost 100%. The chitosan-montmorillonite may be useful as a functional material for dye adsorption and antibacterial applications.

The Journal of Pure and Applied Chemistry Research, 2016

Preparation of sulfonated-kaolin (sKao) has been conducted and used as filler on chitosan matrix via solution casting method, namely chitosan/sKao (Cs/sKao). Swelling degree, cationic exchange capacity and thermal stability were evaluated to determine chitosan/sKao membranes performance as proton exchange membrane in a fuel cell. Functional group analysis of chitosan, sKao and synthesized products were studied using Fourier Transform Infra-Red (FTIR) spectroscopy. In this study, swelling degree and swelling area of Cs/sKao were also examined to determine of membrane ability to swelling which compare to unmodified chitosan/kaolin (Cs/Kao). The presence of sKao in chitosan matrix was able to improve cationic exchange capacity (CEC) which proved by the morphological study of membrane surface after CEC test. Moreover, Thermal stability of Cs/sKao showed the membrane has meet requirement for Proton Exchange Membrane (PEM) application.

Malaysian Journal of Fundamental and Applied Sciences

The chitosan/organo-montmorillonite (Ch/O-MMT) membrane was fabricated and tested. Surface modification of O-MMT particles using 3-glicydoxy propyl trimethoxysilane (GPTMS) to enhance its compatibility with chitosan is presented. The resulting composite membrane was characterized by using SEM, AFM, and FTIR to observe the morphological and functional group structure. The crystallinity, thermal stability, and mechanical strength was analyzed by XRD, TGA, and tensile test. The results suggested that the modification of MMT using GPTMS could increase the compatibility of O-MMT with chitosan membrane, thus producing a good composite membrane with well-dispersed MMT filler within the chitosan polymer matrices. Based on the FTIR analysis, the presence of GPTMS could improve the interaction between chitosan and O-MMT material, thus forming more hydrogen bonding with chitosan membrane than Ch/MMT membrane. The TGA curve analysis showed that the addition of inorganic filler into chitosan org...

Journal of Macromolecular Science, Part B, 2013

A polyelectrolyte complex (PEC) of chitosan and phosphotungstic acid (PWA) was prepared and characterized as a proton-conducting membrane for direct methanol fuel cell (DMFC) applications. Fourier transform infrared spectroscopy showed the presence of stable PWA in PEC. To reduce the methanol permeability, several amounts of montmorilonite (MMT) nanoclays (trade name: Cloisite Na) were introduced to the system. The X-ray diffraction patterns of nanocomposite membranes proved the nanoclay layers were exfoliated in the membranes at loading weights of MMT lower than 3 wt%. Proton conductivity and methanol permeability were measured. According to the selectivity parameter-ratio of proton conductivity to methanol permeability-PEC containing 2 wt% MMT (PEC/2 wt% MMT) was identified as the optimum composition. Finally, DMFC performance tests were investigated at 70 • C and 5 M methanol feed and the optimum membrane showed higher maximum power density in comparison with Nafion 117. The results indicated the optimum nanocomposite membrane is a promising polyelectrolyte membrane (PEM) for DMFC applications.