Controlled Release from Model Blend Multilayer Films Containing Mixtures of Strong and Weak Polyelectrolytes

We have designed the controlled release platforms based on polyelectrolyte (PE) blend multilayer films to investigate the release mode and kinetics at the nanoscale level. The model blend multilayer films are composed of positively charged layers with weak polyelectrolytes (PEs) (linear poly­(ethylenimine), LPEI) and negatively charged blend layers with mixtures of strong (poly­(sodium 4-styrenesulfonic acid), PSS) and weak (poly­(methacrylic acid), PMAA) PEs. The blend multilayer films ([LPEI/PSS:PMAA]_<i>n</i>) with well-defined internal structure were prepared by the spin-assisted layer-by-layer (LbL) deposition method. Release properties of the multilayer films were systematically studied as a function of blend ratio by neutron reflectivity (NR), ellipsometer, AFM, FT-IR spectroscopy, and quartz crystal microbalance with dissipation (QCM-D). Since PSS strong PEs serve as robust skeletons within the multilayer films independent of external pH variation, the burst disruption of pure weak PE multilayer films was dramatically suppressed, and the release kinetics could be accurately controlled by simply changing the PSS content within the blend films. These release properties of blend multilayer films form the basis for designing the controlled release of target active materials from surfaces