Influence of Polycation (PDADMAC) Weight on Vertical Diffusion within Polyelectrolyte Multilayers during Film Formation and Postpreparation Treatment

Abstract

The internal interfaces of polyelectrolyte multilayers are investigated with neutron reflectivity. The films are made from poly(diallyldimethylammonium) (PDADMA), poly(styrenesulfonate) (PSS), and deuterated PSS-d. Each film consists of a protonated and a deuterated block. The internal roughness is smallest next to the film/air interface and increases with the number of layer pairs away from the film/air interface until a metastable state is reached. Both the final internal roughness and the interdiffusion constant increase with the salt concentration in the deposition solution and with PDADMA polymer weight. The increased mobility found with high molecular weight PDADMA is attributed to residual stresses occurring during film formation. The experiments suggest that PSS and PDADMA move partly as a complex. Postpreparation immersion in 1 M NaCl salt solutions has little effect if the multilayer is prepared from low salt solution and with high molecular weight PDADMA. However, almost complete intermixing is observed for multilayers prepared from 0.1 M NaCl and with low molecular weight PDADMA (diffusion length exceeds 30 nm).

Fourier transform infrared spectroscopy investigation of water microenvironments in polyelectrolyte multilayers at varying temperatures

“…phase-determining factor. 18,25 Asides from salt, the polyelectrolyte mixing ratio, 18,23 mixing order, polyelectrolyte molecular weight, 7,26 charge density, 18,22 water content 27,28 and, temperature. prepared by a layer by layer technique.…”

Diffusion of Sites versus Polymers in Polyelectrolyte Complexes and Multilayers

“…With polyelectrolytes of sufficiently low molecular weight 16 or weak enough interactions (high enough salt concentration), it is possible that polymer diffusion may rival site diffusion, i.e. D pol approaches D* (it is unlikely that D pol exceeds D*).…”

Influence of the degree of ionization on the growth mechanism of poly(diallyldimethylammonium)/poly(acrylic acid) multilayers

“…The interdiffusion of chains in a multilayer as an underlying mechanism for exponential growth, which was established since a long time in PEM of biopolymers could be a potential mechanism even in exponentially growing strong polyelectrolytes. Recently, neutron reflectivity was applied to demonstrate an interdiffusion of chains in PEM of some synthetic polyelectrolytes …”