Biopolymer Precursors Research Articles

Fabrication and characterization of PVA/ODA-MMT-poly(MA-alt-1-octadecene)-g-graphene oxide e-spun nanofiber electrolytes and their response to bone cancer cells

This work presents a new approach to fabrication and characterization of novel polymer nanofiber electrolytes from intercalated PVA/ODA-MMT nanocomposite as a matrix polymer and encapsulated graphene oxide (GO) nanosheets with amphiphilic reactive copolymer as partner polymers using electrospinning method. The chemical and physical structures, surface morphology, thermal behaviors and electric conductivity of nanocomposites and nanofibers were investigated using analyses methods including FTIR, XRD, SEM, DSC-TGA and conductivity analysis. Significant improvements in nanofiber morphology and size distribution were observed when GO and reactive organoclay were incorporated as reinforcement fillers into various matrix/partner solution blends. The structural factors of matrix-partner polymer nanocomposite particles with higher zeta-potential play important roles in both chemical and physical interfacial interactions and phase separation processing and also lead to the formation of nanofibers with unique surface morphologies and good conductivities. The cytotoxic, necrotic and apoptotic effects of chosen nanofibers on osteocarcinoma cells were also investigated. These multifunctional, self-assembled, nanofibrous surfaces can serve as semi-conductive and bioactive platforms in various electrochemical and bio-engineering processes, as well as reactive matrices used for the immobilization of various biopolymer precursors.

Bio-Polymer Derived Activated Carbons for Electrochemical Double Layer Capacitors

Electrochemical double layer capacitors (EDLCs), are energy storage devices featuring many advantages, including long cycle life, low internal resistance, and high power densities (i.e. fast charge/discharge rates). Due to these advantages EDLCs have drawn much attention recently, and have been applied to electric/hybrid vehicles, heavy-construction equipment, electronics, and grid utility storage. The most common electrode material for EDLCs is porous activated carbon with the advantages of low cost, abundant resources, and simple processing. In this present work, carbon materials for EDLCs were hydrothermally synthesized from low-cost bio-polymer precursors. Hydrothermal synthesis (HTS) uses simple equipment and runs under mild conditions; the process also uses environmentally friendly precursors and does not produce any hazardous waste. HTS provides a facile method for the development of inexpensive, high- performance carbon materials.In this work, low cost precursors were obtained locally. The precursors were ground and mixed with DI water, and the solution was then sealed in a Teflon lined pressure vessel. The pressure vessel was heated to 200 °C for 24 hours. After the reactor cooled down, the as-synthesized carbons were harvested by filtration and dried in an oven at 120 °C overnight. The morphology of the as-synthesized carbons was characterized by scanning electron microscopy (SEM) as shown in Figure 1. The as-synthesized carbons went through a one-step activation, which increased the surface area to over 1000 m2/g, with 70% micro porosity. Electrodes were made, and tested in 1.8M TEMABF4in PC and 38% sulfuric acid. Cyclic voltammetry (CV) and galvanostatic charge-discharge tests were run on these activated carbons to study the electrochemical performance. The activated carbons showed very nice capacitor characteristics such as rectangular CV curves and very fast charge-discharge rates in both organic and aqueous electrolytes, as shown in Fig 2. The specific capacitance of these materials in organic electrolyte was ~90-120 F/g and had a volumetric capacitance of ~40-60 F/cc, while in aqueous electrolyte the gravimetric capacitance ranged from 180-200 F/g and 100-120 F/cc.

Oxidation of Some Sulfated Carbohydrates: Kinetics and Mechanism of Oxidation of Chondroitin-4-Sulfate by Alkaline Permanganate with Novel Synthesis of Coordination Biopolymer Precursor

The kinetics of oxidation of chondroitin-4-sulfate as sulfated carbohydrates by alkaline permanganate has been investigated spectrophotometrically. The oxidation reaction was found to proceed through two-distinct stages. The first stage was found to be relatively fast involving the formation of unstable green [CS, MnVIO42-] and blue [CS, MnVO43-] biopolymeric coordination intermediates at wavelengths of 610 and 730 nm, respectively. The second stage was corresponding to a slow decomposition of such intermediates to give rise to keto-acid derivative and soluble-colloidal manganese (IV) as final oxidation products. The oxidation reaction was found to be base-catalyzed. The kinetic parameters have been evaluated and a tentative oxidation reaction mechanism in good consistent with the kinetic results was suggested and discussed. Novel keto-acid derivative has been synthesized. The reaction product was characterized and identified by elemental analysis and spectral data.

New synthesis of nanosized Cu–Mn spinels as efficient oxidation catalysts

Copper manganese nanoscale oxides were prepared using a novel method with low cost natural biopolymer precursor, alginate, and their catalytic activity was evaluated for the complete oxidation of toluene as a model VOC. Depending on the Cu/Mn ratio the following oxides were formed: Mn3O4, Cu1.5Mn1.5O4, CuO or a mixture of these phases, as detected by XRD. The nanocrystals aggregate in small spheres (≲1mm), which retain the shape of the parent gel and present homogeneous composition as characterized by TEM and SEM-EDX. The best performance for toluene combustion was observed for the cubic spinel Cu1.5Mn1.5O4 nanoparticles (∼10nm), which was able to completely oxidize toluene at ∼240°C. For the pure oxides the activity order: Cu1.5Mn1.5O4>Mn3O4>CuO, correlates with the TPR results as the catalyst with the higher redox potential shows higher activity. For comparison the TiO2 supported oxides were also studied and alginate issued Cu1.5Mn1.5O4 mixed with TiO2 presented similar activity as the Cu–Mn oxide deposited on TiO2 by incipient wetness impregnation however the overall activity of supported oxides was lower than for the unsupported Cu1.5Mn1.5O4. The method used for the synthesis of copper manganite has great potential as it can be extended to other manganite spinels of general formula AMn2O4 and presents the advantage of easy catalyst forming.

Alginate polyelectrolyte ionotropic gels. VI. Novel synthesis of diketoalginates as biopolymer precursors

AbstractSodium 2,3‐diketoalginate was quantitatively prepared by the oxidation of sodium alginate with potassium permanganate in alkaline solution at pH's > 12. The yield was 96.5%. The structure of the diketone was elucidated by microanalysis and spectroscopic data. It was found that the diketoalginate caused no gelation or precipitation with copper(II), nickel(II), or cobalt(II) divalent metal ions. © 1993 John Wiley & Sons, Inc.