Aim and background
Polyelectrolyte multilayers (PEM) are known since the pioneerining work of Decher (Thin Solid Films, 210/211, 831 (1992)) in the early nineties. Since then scientific papers appeared with an exponentially growing number versus year. PEM can be easily deposited on nearly every material surface and shape (planar substrate, fibers, particles etc.) by the consecutive adsorption from polycation (PC) and polyanion (PA) solutions. Different fundamental issues are addressed by the polymer and colloid community like e.g. the growth mechanism, overcompensation, location of the counterions and “fuzzy” or ordered internal structure as well as applied issues like e.g. biomedical surface modification or generation of specific layered architectures for optical, electronic or sensor applications. In that context our research activities with PEM are going in three main directions:
- Variation of parameters concentration, pH and ionic strength to control deposition
- Creation of defined PEM nanostructures by incorporation of stiff PEL to generate oriented PEM nanostructures
- PEM/Protein and PEM/chiral probe interaction studies aiming at protein location (surface or bulk phase), protein selectivity and enantiospecifity.
Materials and Methods
Flexible and stiff polyelectrolytes (PEL) are used like branched poly(ethyleneimine) (PEI, Mw = 750.000 g/mol), poly(diallyldimethylammonium chloride) (PDADMAC, Mw = 250.000 g/mol), poly(L-lysine) (PLL, Mw = 20.000-300.000 g/mol), PAC poly(acrylic acid) (PAC, Mw= 50.000 g/mol), poly(vinylsulfate) (PVS, Mw = 160.000 g/mol), poly(styrene sulfonate) (PSS, Mw= 5.000-1.000.000 g/mol) and poly(L-glutamic acid) (PLG, Mw = 70.000 g/mol). Characterization of consecutive deposition of the polyelectrolytes and of the deposited PEMs is mostly performed by in-situ-ATR-FTIR spectroscopy (Fig. 1) using the SBSR concept (OPTISPEC, Zürich, Switzerland) to obtain well compensated ATR-FTIR spectra. Polarized IR light is used for dichroic measurements. AFM measurements are performed mostly in non contact mode on the Ultramiscroscope consisting of optical microscope and AFM attachment (SIS GmbH, Herzogenrath, Germany).
 M. Müller, J. Meier-Haack, S. Schwarz, H.M. Buchhammer, K.J. Eichhorn, A. Janke, B. Keßler, J. Nagel, M. Oelmann, T. Reihs, K. Lunkwitz, J. Adhesion, 80(6), 521-548 (2004)
 M. Müller, B. Kessler, K. Lunkwitz, J. Phys. Chem., 107 (32), 8189-8197 (2003)
 M. Müller, W. Ouyang, B. Keßler, Intern. J. Polymer. AC, 12, 1-11 (2007)
 M. Müller, B. Keßler, W. Ouyang, Z.Phys.Chem., 221 127-138 (2007)
 M. Müller, B. Keßler, N. Houbenov, K. Bohata, Z. Pientka, E. Brynda, Biomacromolecules, 7(4), 1285-1294 (2006)