Preparation and properties of chitosan/carbon nanotube nanocomposites using poly(styrene sulfonic acid)-modified CNTs
R&D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, #200, Chung-Pei Road, Chungli, Taoyuan 32023, Taiwan Carbohydrate Polymers
(Impact Factor: 4.07).
03/2009; 76(2):232-238. DOI: 10.1016/j.carbpol.2008.10.021
Poly(styrene sulfonic acid)-functionalized carbon nanotubes (CNT-PSSA), which was obtained with atom transfer radical polymerization (ATRP), was utilized in preparation of chitosan/CNT nanocomposites (CH/CNT-PSSA). Chemical linkages between chitosan and CNTs form in the nanocomposites through the reaction between the sulfuric acid groups of CNT-PSSA and the amino groups of chitosan, to warrant the homogenous dispersion of CNTs. The CH/CNT-PSSA nanocomposites were superior to the neat chitosan polymer in thermal and mechanical properties, water and solvent uptakes, bond water ratios, and electrical conductivity. The attractive property of the CH/CNT-PSSA nanocomposites also implied their application potentials for separation membranes and sensor electrodes.
Available from: Wei Chu
- "were many experimental investigations about modifying CNTs by means of grafting CS on CNTs. Appropriate surface functionalization on CNTs are effective ways to promote the CS-CNT interactions   . However, the molecular structures of CS-functionalized CNT composites are still unknown, which limited the structure design and functionalization strategies of the nano-composites. "
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ABSTRACT: The effect of types of CNTs (pristine and hydroxylated) on the synthesis of Chitosan-CNT (CS-CNT) composites was investigated theoretically. The adsorption energy (Eads) of CS on the pristine CNT and hydroxylated CNTs (CNT-OHn, n = 1–6) as well as the structural and electronic properties of said composites have been investigated. Results show that the adsorption of CS on CNT and CNT-OHn is thermodynamically favored. The Eads of CS on CNTs was calculated to be −20.387 kcal/mol from electrostatic interactions. For CS adsorbed into CNT-OHn, Eads ranges from −20.612 to −37.567 kcal/mol. Hydroxyl groups on CNT are the main adsorption sites for CS loading onto CNT-OHn via hydrogen-bond interactions. The CS-CNT-OH3 is the most sable composite among tested complexes. The energy gap (ΔEgap) of CS-CNT-OH3 was calculated less than pristine CNT and CNT-OH3, indicative of the composites being more reactive than that of pristine CNTs and CNT-OH3. It was proved that CS can transfer electron to the hydroxylated CNTs, thus overcoming the drawbacks of CNTs being chemically inert.
Available from: Rangika Thilan De Silva
- "Different types of material as micro and nanofillers, such as silica, hydroxyapatite, calcium phosphate, carbon nanotubes (CNTs)  and organo modified montmorillonite (OMMT), have been studied for reinforcing chitosan . Of these, CNTs and OMMT have shown potential for reinforcing and enhancing the thermal stability of chitosan membranes    . Nevertheless, it is well known that the synthesis and functionalization processes of CNTs are complicated and costly . "
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ABSTRACT: Chitosan membranes reinforced by halloysite nanotubes (HNTs) at concentrations from 2 to 15 (w/w%) have been prepared by solution casting to investigate the optimal physico-chemical properties for biomedical applications. Tensile test data revealed that the membranes reinforced with 5 (w/w%) HNTs yielded the highest Young's modulus (0.52 ± 0.01 GPa) and strength (81.6 ± 4.4 MPa). Electron micrographs of the fractured surfaces implicated the interplay between individual HNTs and agglomerates of HNTs in the stress transfer mechanism. Infrared spectra revealed interaction between the HNT siloxane and chitosan functional groups. Thermogravimetric results demonstrated that the thermal stability of the membranes increased with HNT concentration.
Available from: Tai-Shung Chung
- "Tailoring external surface of nanoparticles with various chemical modifications      and designing molecular-level MMMs using cyclodextrin have been proposed  . "
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ABSTRACT: Novel mixed matrix membranes made of polyether-block-amide/polyhedral oligosilsesquioxane (Pebax/POSS) have been developed and investigated in this study for ethanol recovery via pervaporation separation. Two types of POSS; namely, octa(3-hydroxy-3-methylbutyldimethylsiloxy) (AL0136) and disilanolisobutyl (SO1440), were incorporated into Pebax membranes. The effects of POSS loading, feed ethanol concentration and feed temperature on pervaporation performance of the newly developed mixed matrix membranes (MMMs) have been studied. The incorporation of POSS nanoparticles improve the pervaporation performance of the hybrid membranes significantly. At 2wt.% POSS loading, both permeation flux and separation factor of ethanol/water reach maximum values, which are 183.5g/m2h and 4.6 for Pebax/AL0136 and 125.8g/m2h and 4.1 for Pebax/SO1440, respectively. Pebax/AL0136 MMMs give better performance than Pebax/SO1440 MMMs, probably due to its higher affinity towards ethanol. Experimental results show that an increase in feed ethanol concentration results in an increase in flux, but decreases in separation factor and membrane selectivity. Flux increases but permeability decreases with an increase in operating temperature due to the increase in driving forces and the reduction in permeant sorption, respectively. Separation factor and selectivity are also observed to increase with increasing operating temperature. The changes in driving force, cluster formation, membrane swelling and interaction among permeating molecules play essential roles for the observed trends. This work may provide useful insights of mixed matrix membranes, especially those containing POSS for pervaporation recovery applications.
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