COLL 375 |
| Herein we report on the preparation of polyelectrolyte (PEL) complex (PEC) nanoparticles and simulation results in an attempt to describe the PEC formation process using a model based on colloidal particle coagulation. PEC nanoparticle dispersions are of large scientific interest and practical application in e.g. water treatment (flocculation), biomedicine (drug/protein carrier) and as coating material. The background of this work is related to the improvement of PEC dispersions with respect to stability, narrow size distribution and defined size regulation [1]. PEC dispersions were prepared by mixing aqueous solutions of cationic poly(diallyldimethylammonium chloride) (PDADMAC) and of anionic poly(styrenesulfonate) (PSS) at nonstoichometric monomer charge ratios and were characterized by dynamic light scattering. The formed PEC particles are actually accepted, to consist of a charge compensated neutral core and a charged shell formed by the excess PEL [2]. In order to regulate the size of the particles we varied the salt concentration cS of the solution and polyelectrolyte concentration cPEL. Additionally the influence of polyelectrolyte molecular weight, Mw, on PEC particle size was investigated. Principally, the experimental data suggested two cS dependent regimes for all Mw: For increasing low cS a size decrease due to polyelectrolyte nature (i), while for increasing higher cS a size increase due to colloidal aggregation (ii) was obtained. Concerning to the second regime (ii) simulations on PEC particle growth were performed. The computational model was based on the Smoluchowski theory and Fuchs' theory of coagulation including an interaction potential between colloidal particles according to DLVO theory. As a result the systems simulated at different Debye length show that the l dependence of PEC particle size is in accordance to the experimental finding. [1] M. Müller, B. Kessler, S. Richter, Langmuir, 2005, 21, 7044-7051. [2] H. Dautzenberg, Macromolecules 1997, 30, 7810-7815 |
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Polymer-Nanoparticle Systems: Theory, Simulation, Experiments
9:00 AM-12:00 PM, Wednesday, April 9, 2008 Morial Convention Center -- Rm. 227, Oral
Division of Colloid & Surface Chemistry |