NAMS 2002 Workshop - ICOM 2008

Polymeric Membranes I – 1 – Keynote
Monday July 14, 9:30 AM-10:15 AM, Moloka’i
Layer-by-Layer Assembly in Membrane Pores for Ion Separations and
Biocatalysis
D. Bhattacharyya (Speaker), University of Kentucky, Lexington, KY, USA, db@engr.uky.edu
A. Hollman, University of Kentucky, Lexington, KY, USA
A. Butterfield, University of Kentucky, Lexington, KY, USA
V. Smuleac, University of Kentucky, Lexington, KY, USA
S. Datta, University of Kentucky, Lexington, KY, USA
The development of new-generation materials that extend the industrial
applications of membrane processes will require a high level of control of both
the characteristics of the base polymeric or inorganic support layer, as well as, its
corresponding surface properties. Current research in membrane science is now
focusing more on the modification of surface physical along with chemical
properties using techniques like plasma or radiation-induced polymer grafting,
immobilization of reactive ligands, layer-by-layer assembly, etc. Membranes
functionalized with appropriate macromolecules can indeed provide applications
ranging from tunable flux and separations, toxic metal capture, to nanoparticle
synthesis for toxic organic dechlorination. Microfiltration membranes (eg,
cellulosics, silica, polysulfone, polycarbonate, PVDF) can be functionalized with a
variety of reagents. Depending on the types of functionalized groups (such as,
chain length, charge of groups, biomolecule, etc.) and number of layers, these
microfiltration membranes could be used in applications ranging from metal (or
oxyanions) separation to biocatalysis. The dependence of conformation
properties of polyelectrolytes on pH also provides tunable separation and flux
control.
Layer-by-layer (LBL) assembly technique, most commonly conducted by
intercalation of positive and negative polyelectrolytes or polypeptides, is a
powerful, versatile and simple method for assembling supramolecular structures .
Non-stoichiometric immobilization of charged polyelectrolyte assemblies within
confined pore geometries leads to an enhanced volume density of ionizable
groups in the membrane phase. This increase in the effective charge density
allows for Donnan or charge-based exclusion of ionic species using porous
materials characterized by hydraulic permeability values well beyond
conventional membrane processes. Multilayer assemblies were fabricated using
both PLGA (poly-L-glutamic acid)/PLL(poly-L-Lysine) and synthetic
polyelectrolytes (poly(styrene sulfonate)/poly(allylamine)) in an attempt to
compare the level of adsorption and separation properties of the resulting
materials. The role of salt concentration in the carrier solvent on overall
polyelectrolyte adsorption was examined to determine its effect on both solute