Optical, structural and adsorption properties of zinc peroxide/hydrogel nanohybrid films
ABSTRACT Hybrid nanofilms from zinc-peroxide/poly(acrylamide) (ZnO2/PAAm) and zinc-peroxide/poly(N-isopropyl-acrylamide) (ZnO2/PNIPAAm) were prepared using the photopolymerization procedure. The thin layers were prepared by the combination of the Layer-by-Layer (LbL) self-assembly method and photopolymerization using UV light in every step of the procedure. The hybrid multilayer films consisting of layers of zinc peroxide nanoparticles and hydrogel alternating in a sandwich-like fashion with thicknesses of 65–246 nm. The chemical structures of the hybrid films were investigated by FTIR spectroscopy, their morphology was studied by atomic force microscopy (AFM). The build up of the films was studied by measuring the optical reflection spectrum, and we have calculated the refractive index and layer thickness of the hybrid layers using simulating software. The adsorption properties of the ZnO2/hydrogel nanohybrid composite networks were investigated by measuring water and ethanol vapour adsorption by a quartz crystal microbalance (QCM). It was established that on partially hydrophobic ZnO2/PNIPAAm hybrids the adsorbed amounts were lower, against the hydrophilic ZnO2/PAAm film the vapour amount was higher. These results correspond to those of the bulk gel swelling results.
- SourceAvailable from: Robert Speight
[Show abstract] [Hide abstract]
- "The development of humidity sensors based on QCM attracted the interest of a number of researchers and a range of surface components were investigated for the detection and quantification of water vapour. Examples of such surface components included porphyrins (Korposh et al., 2010), novel ruthenium polypyridyl complexes (Ocakoglu and Okur, 2010), sulfonated calix arene (Okur et al., 2010a; Okur et al., 2010b), zinc peroxide in a hydrogel (ethanol vapours were also detected) (Sebok et al., 2010), nanofibrous polyacrylic acid/poly(vinyl alcohol) (Wang et al., 2010b), polyethylene imine/chitosan (Wang et al., 2010d), a sulfonated tetrafluoroethylene polymer (Nafion) (Wu et al., 2010b) and mesoporous silica (Zhu et al., 2010). Water vapour, as well as other polar molecule vapours, were assessed for binding to calcein thin films and QCM was used alongside surface plasmon resonance and visible spectroscopy to find that calcein films were highly sensitive compared to similar surfaces (Kruglenko et al., 2010). "
ABSTRACT: In 2010 there has again been an increase in the number of papers published involving piezoelectric acoustic sensors, or quartz crystal microbalances (QCM), when compared to the last period reviewed 2006-2009. The average number of QCM publications per annum was 124 in the period 2001-2005, 223 in the period 2006-9, and 273 in 2010. There are trends towards increasing use of QCM in the study of protein adsorption to surfaces (93% increase), homeostasis (67% increase), protein-protein interactions (40% increase), and carbohydrates (43% increase). New commercial systems have been released that are driving the uptake of the technology for characterisation of binding specificities, affinities, kinetics and conformational changes associated with a molecular recognition event. This article highlights theoretical and practical aspects of the principals that underpin acoustic analysis, then reviews exemplary papers in key application areas involving small molecular weight ligands, carbohydrates, proteins, nucleic acids, viruses, bacteria, cells, and membrane interfaces.Journal of Molecular Recognition 09/2012; 25(9):451-73. DOI:10.1002/jmr.2209 · 2.34 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: The surface treatment with boiling hydrogen peroxide (H2O2) solution on the surface of ZnO nano-columnar film was investigated. Field emission-SEM and TEM analysis revealed that amorphous ZnO2 layer covers the ZnO nano-column surface through the H2O2 treatment at 100°C for 1 min. X-ray photoemission spectroscopy (XPS) has been conducted on the H2O2 treated ZnO surface. The surface exhibits high resistive conductivity after the H2O2 treatment, suggesting that the treatment promotes a compensation effect. We demonstrate that dramatic improvement in the rectifying behavior on the Schottky diodes can be achieved by inserting a ZnO2 interface layer between the Pt Schottky electrode and the ZnO nano-column film. The ZnO2 interface layer promotes surface passivation and suppresses the surface leakage current. This is expected to increase the Schottky barrier height to 0.78 eV. The H2O2 treated Schottky diode showed five orders of magnitude in current rectification between forward and reverse bias at 3 V.Journal of Applied Physics 05/2011; 109(9):093517-093517-7. DOI:10.1063/1.3582143 · 2.19 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: In the present work, the abilities of chitosan-g-poly(acrylic acid)/ vermiculite (CTS-g-PAA/VMT) hydrogel composites to remove Pb(II) and Cd(II) ions from aqueous solutions were compared. Batch adsorption studies were carried out to examine the influence of various parameters such as the VMT content, the initial pH value, the contact time, the initial metal ion concentration on adsorption capacities. Adsorption of Pb(II) and Cd(II) ions on the composite showed a pHdependent profile. The maximum adsorption capacity for both metal ions was found to lie between 5.5 and 6.00. The adsorption processes were all relatively fast. Over 90% of the total adsorption was reached in around 3 min for both Pb(II) and Cd(II) adsorption at 303 K, and the equilibrium was reached after about 15 min of contact time. The adsorption data for the composite fitted well not only the Langmuir model but also the Freundlich model. The maximum Pb(II) adsorption capacity (3.0774 mol/g) of the composite is only a litt le more than that of Cd(II) (2.9817 mmol/g) at 303 K, however, the desorption efficiency of Pb(II) loaded sample (63.27%) is much lower than that of Cd(II) loaded sample (86.26%) when 0.1 mol/L HNO3 solution was used as the elutent. The adsorption of Pb(II) and Cd(II) ions by the composite seemed to involve ion exchange, chelation, electrostatic att raction or adsorption. –NH2, –COOH and –OH groups are all involved in the adsorption processes. Moreover, there are only few of –NH2 groups participating in the reaction with Pb(II) ions.Desalination and water treatment 11/2012; 48(1):38-49. DOI:10.1080/19443994.2012.698793 · 1.17 Impact Factor