Papers by Keyword: Polyelectrolyte

Abstract: We have shown how different micellar (SDBS) vs. polyelectrolytic (PSSA) supramolecular assemblies in post-CMP cleaning solutions differ in their tribological performance when used in a novel PVA scrubber for 300-mm silicon dioxide wafer cleaning. Significant differences in real-time shear force and coefficient of friction data from the wafer-solution-brush interface (both in time domain as well as frequency domain) have been attributed to differences in each supramolecule’s chemical functionality and structure, which in turn, have been correlated to wafer-level defects. The work has underscored the importance of measuring the tribological attributes of post-CMP cleaning processes in an effort to improve cleaning performance.

Abstract: In this work, a weft-knitted fabric produced from 100% meta-aramid (MA) fibre was functionalized by using polyelectrolyte, Poly (diallyldimethylammonium chloride) (PDDA), in order to modify its surface for dyeing with an uncommon dye class for MA fibres. Contact angle, dye solution drop adsorption, Scanning Electron Microscopy (SEM), reflectance spectrophotometry, washing and rubbing fastness tests were performed to study the effects caused by the interaction between PDDA and MA fabric. Good results of dyebath exhaustion with excellent values of colour strength were obtained for the samples previously treated with PDDA. These results showed the possibility of obtaining distinct and deep colours besides generating a lower energetic cost using shorter time and lower dyeing temperature as compared to those normally used in the MA dyeing process.

Abstract: In this paper, the possibility of replacing liquid electrolyte in a dye sensitized solar cells with a thin film of conductive polymer material was investigated. Liquid electrolyte in the construction of dye sensitized solar cells leaks and evaporates and leads to corrosion of the electrode, which lowers the conversion efficiency of solar radiation to electricity. The research focuses on the appropriate doping of the PVDF-HFP polymer by potassium iodide to improve its electrical conductivity and the development of thin film deposition technology for use in solar cells. Changes in PVDF-HFP surface morphology were researched through increasing of the potassium iodide content measured by scanning electron microscope. The increased content of potassium iodide also led to increased electrical conductivity measured by the Keithley meter. In order to test the suitability of developed materials for application in the construction of photovoltaic cells, a series of dye-sensitized solar cells ITO/TiO2/dye/active layer/Al were prepared. The active layer is made from pure PVDF-HFP and doped with potassium iodide. As a reference solar cell, a standard dye sensitized solar cell with a liquid electrolyte and a counter electrode was also made. Keywords PVDF-HFP; Polyelectrolyte; Dye-sensitized solar cells

Abstract: This paper describes the results of studies on the synthesis and functionalization of the surface of nanoscale and ultradispersed copper powders in the production process. The principles of deagglomeration and specific problems for Nanoparticles are considered. The paper presents data on stabilization of copper nanoparticles in the process of obtaining, highlights the problems that require a good understanding, namely the study of the behavior of different types of ultra and nanoscale copper powders in the processes related to production of polymeric composite materials.

Abstract: In this study flax fabrics were treated with polyethylene imine (PEI) and afterwards, in combination with carbon fabrics, integrated into epoxy resin via vacuum infusion process. The influence of the 2 stacking sequences of the fabrics and 2 PEI concentrations were evaluated with regard to the mass fractions of the composite components and mechanical properties of the manufactured composites, namely, flexural and interlaminar shear properties. The results showed that the effect of the surface treatment is dependent on the stacking sequence. Namely, increase of the PEI concentration resulted in a corresponding increase of the mass fraction of the polymer matrix in the case of interchanging arrangement of flax and carbon fabrics. Further remarkable results showed that the same specimen provided the highest values of the supported maximum load after the surface treatment. Influence of the PEI treatment on the strength values with regard to the stacking sequence and polyelectrolyte concentration led to controversial results. Decrease of flexural modulus after the surface treatment was observed in the case of all samples.

Abstract: Molecular dynamics are applied to simulate molecular motions in an aqueous solution of two soluble derivatives of a 100-ring polythiophene chain – one with sidechains terminating in a SO₃^– group, the other in NMe₃⁺. Each chain is in a helical conformation defining a water-containing central channel along whose axis the dynamics of ions from the solution to the channel’s axial electrostatic potential is simulated. The profiles of these potentials distinguish the tendencies of the two channel species to occlude water molecules on their surfaces. Invoking the conductive polymer characteristics of polythiophene that can accomplish the transfer of electrons between the aromatic rings and redox reagents in the solution, the effect of this transfer on the axial potential and migration is followed. The electrostatic potential monitors differences in the association of the solvent molecules with the two species of helical polymer and shows that while Na⁺ and Cl^– ions do not enter the channel in the absence of the redox changes, an ion with a selected charge does so spontaneously when appropriate electric charge is transferred to the channel. This enables the selected ion to travel about 10 – 20Å in the channel without the application of an external electric field.

Abstract: Nanofiltration membrane was prepared by static layer-by-layer (LBL) self-assembly of poly (ethyleneimine) (PEI) and poly (sodium 4-styrenesulfonate) (PSS) on the modified poly-arcylonitrile ultra-filtration membrane. Study on self-assembly of polyelectrolyte membranes with changing surface charges and wettability, rejection properties of nanofiltration membrane in different conditions and pH with respect to heavy metal ions, namely Ni²⁺ and Cd²⁺were investigated. The results show that the PEI/PSS membrane composed of 4 bilayers at operating pressure 0.4MPa, rejection of PAN-PEI/PSS nanofiltration membrane towards these 2 kind of heavy metal ions reached no less than 90%.

Abstract: The design of new technologies for treatment of human disorders is a complex and difficult task. The aim of this article is to explore state of art discussion of various techniques and materials involve in cell encapsulations. Encapsulation of cells within semi-permeable polymer shells or beads is a potentially powerful tool, and has long been explored as a promising approach for the treatment of several human diseases such as lysosomal storage disease (LSD), neurological disorders, Parkinsons disease, dwarfism, hemophilia, cancer and diabetes using immune-isolation gene therapy.

Abstract: Fibrinogen adsorption onto surface-attached poly(methacrylic acid) monolayers and poly(methacrylic acid)/polyethyleneimine bilayers has been investigated. The adsorbed amount of fibrinogen was found to be dependant on the charge sign of the topmost layer because of electrostatic interactions.

Abstract: This study deals with the fabrication and characterization of polymer matrix thin films containing high content titanium dioxide (TiO₂). Poly(diallyldimethylammonium chloride) (PDADMAC) membrane incorporated with different percentages of TiO₂ nanoparticles were prepared by solvent casting. The morphologies of the films were characterised by scanning electron microscopy (SEM), and its thermal behavior were characterised by thermogravimetry(TG). The results indicated that dense TiO₂/polymer thin films can been fabricated conveniently by solvent casting from aqueous solutions of TiO₂/PDADMAC when the concentrations of TiO₂ were lower than 40 wt%, and the thermal stability of the TiO₂/PDADMAC composites were greatly improved by the addition of TiO₂ moieties.