Last update:
08/30/2006
In recent years it has been recognized that nanoscale and molecular level design of surfaces is essential to the development of selective and high response chemical and biological sensors, development of selective membranes for chemical (e.g., pervpaoration of organic liquids and gas separation) and biomedical applications (e.g., in-vivo bioensors, dialysis membranes), tailor-desing of surface properties for lubrication application, adhesion of advanced composites and advanced microelectronics device fabrication. As a result, research efforts have intensified in the areas surface engineering with particular emphasis on molecular recognition of surfaces.
Research efforts on the molecular design of selective interfaces by surface silylation, living free-radical graft polymerization and plasma surface polymerization are the corner stone of this project. The PolySep laboratory has had considerable success in this area with patents on surface design with polymers and the synthesis of a selective membrane for separation of organics and development of selective resins for analysis of and separation of polymers and proteins.
In order to develop the next generation of practical and oust nano-structured surfaces, the topology of tethered polymer interfaces (surfaces consisting of terminally-anchored polymer chains) will have to be carefully studied and optimized through molecular-level design and characterization via control of surface chemical reactions at the "interface" synthesis step. Therefore, the application of nano-technology tools will play a central role in this project. The topology of these surfaces and solute-surface interactions will be studied by atomic force microscopy (AFM). Surface-solute affinity (and uptake) and polymer swelling will be evaluated using a quartz crystal microbalance (QCM) and reverse-phase liquid chromatography. The study will also deal with theoretical modeling of the swelling behavior of the separation layer in relation to surface morphology and chemical functionality. The study will benefit from project (1) and other currently on going studies that will provide the expertise needed to adapt the QCM for the present study. The potential use of such surfaces in chemical sensors or selective membranes for organic separations or organic/water separation (e.g., fuel cells) will also be explored in the present project.
Fundamental areas: surface science, reaction engineering, sensors, electrochemistry, transport phenomena, thermodynamics, polymer science, nano-technology.
References:
- Yoshida, W. H and Y. Cohen, "Topological AFM Characterization of Graft Polymerized Silica Membranes", Journal of Membrane Science, Volume 215, Issues 1-2, 15 April 2003, Pages 249-264
- Yoshida, W, Castro, R. P., Jou, J. D. and Cohen, Y., "Multilayer alkoxysilane silylation of oxide Surfaces," Langmuir, 17, 5882-5888 (2001).
- Cohen, Y., J-D, Jou, W. Yoshida and N. Bei, "Surface Modification of Oxide Surfaces by Graft Polymerization," Book Chapter in "Oxide Surfaces", J. A. Wingrave (Editor), Marcel Dekker, New York, 2001.
- Faibish, Ron and Y. Cohen, "Fouling-Resistant Ceramic-Supported Polymer Membranes for Ultrafiltration of Oil-in-Water Microemulsions", J. Membrane Science, 185, 129-143 (2001).
- Cohen, Y., R. S. Faibish and M. Rovira-Bru, "Polymer-Modified Silica Resins for Aqueous Size Exclusion Chromatography," pp. 263-310, in Interfacial Phenomena in Chromatography, Pefferkorn, E. (Ed.), Marcel-Dekker, New York, (1999).
- Browne, T. and Y. Cohen, "Polymer-Grafted Silica: A Screening System for Polymeric Adsorption Resin Development," Industrial and Engineering Chemistry Research, 32, 716-725 (1993).
 (a) |
 (b) |
| A height histogram
(a) and AFM image (b) of a PVP surface created by a plasma-induced
graft polymerization process.
|
|
AFM Images of Poly (vinyl acetate)-Grafted Silicon Wafers Prepared at Different Initial Vinyl Acetate Monomer Concentrations (10%, 25% and 40%).
300x300 nm 3 D AFM Image of a Poly(vinyl acetate) Grafted Silicon Wafer (Initial Monomer Concentration: 10%).
300x300 nm 3 D AFM Image of a Poly(vinyl acetate) Grafted Silicon Wafer (Initial Monomer Concentration: 25%).
