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Polymer Bilayers (polymer + bilayer)

Distribution by Scientific Domains
Polymers and Materials Science75%

Selected Abstracts

Effect of Perpendicular Shear Force on the Interfacial Morphology of Reactive Polymer Bilayer

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 7 2008
Hwang Yong Kim
Abstract We investigated the effect of shear forces perpendicular to the interface on the interfacial morphology of a reactive bilayer. It was observed that the perpendicular shear force greatly enhanced the roughness of the interface compared with parallel shear force. The main role of in situ formed graft copolymers is not to increase greatly the roughness of the interface, but to stabilize the interfacial morphology. We also observed that microemuslsions were observed at both the PMMA and PS layers, which is distinctly different from the situation obtained under parallel shear force (or without shear) that the microemlusions were seen in only the PMMA layer. [source]

A microfabricated CE chip for DNA pre-concentration and separation utilizing a normally closed valve

ELECTROPHORESIS, Issue 18 2009
Chen-Hua Kuo
Abstract A simple, sequential DNA pre-concentration and separation method by using a micro-CE chip integrated with a normally closed valve, which is activated by pneumatic suction, has been developed. The CE chip is fabricated using PDMS. A surface treatment technique for coating a polymer bilayer with an anionic charge is applied to modify the surface of the microchannel. A normally closed valve with anionic surface charges forms a nanoscale channel that only allows the passage of electric current but traps the DNA samples so that they are pre-concentrated. After the pre-concentration step, a pneumatic suction force is applied to the normally closed valve. This presses down the valve membrane, which reconnects the channels. The DNA samples are then moved into a separation channel for further separation and analysis. Successful DNA pre-concentration and separation has been achieved. Fluorescent intensity at the pre-concentration area is increased by approximately 3570 times within 1.9,min of operation. The signals from the separation of ,X174 DNA/HaeIII markers are enhanced approximately 41 times after 100,s of pre-concentration time, as compared with the results using a traditional cross-shaped micro-CE chip. These results clearly demonstrate that successful DNA pre-concentration for signal enhancement and separation analysis can be performed by using this new micro-CE chip. [source]

Stabilization of Polymer Bilayers by Introducing Crosslinking at the Interface,

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 12 2006
Narong An
Abstract Summary: Bisphenol A solid epoxy serves as an effective reaction compatibilizer to the bisphenol A polycarbonate (PC)/PMMA bilayer systems. Addition of epoxy to the bottom PMMA layer can retard or even prevent the dewetting of PC films by introducing crosslinking between both components at the interface. This is the first investigation of polymer bilayers stabilized by chemical reactions. AFM topographic image of a representative dewetting hole. [source]

Formation and characterization of polymersomes made by a solvent injection method

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2007
M. E. Yildiz
Abstract In this article a solvent injection method is described for vesicle formation using poly(butadiene)- b-poly(acrylic acid) diblock copolymers as the amphiphilic molecules. Vesicles composed of polymer bilayers are commonly referred to as polymersomes. Solvent injection is shown to be a rapid method for polymersome formation suitable to make large volumes of polymersome solution. The method can be manipulated to obtain a wide range of vesicle sizes depending on the polymer concentration and preparation conditions. Polymersome solutions in this study are characterized using dynamic light scattering (DLS), fluorescent microscopy, and electron microscopy. Polymersome sizes range from tens of nanometers to several microns. The membrane thickness of smaller polymersomes is found to lie between 14,20,nm. Larger polymersomes are found to have somewhat thicker membranes. The procedure involves the addition of polymers dissolved in an organic solvent to a stirred aqueous solution. The formation of polymersomes by this method is proposed to be governed by the limited mutual solubility of the two solvents and the simultaneous diffusion of solvent and water out of and in to initially formed organic solvent droplets. Copyright © 2007 John Wiley & Sons, Ltd. [source]