Influence of the Assembly Conditions on the Growth and Disassembly of Layer-by-Layer Films
Vishvakant Mankad, Ravin
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A central aim of our research is to capitalize upon the versatility of the Layer-by-layer (LbL) assembly technique and explore parameters to control the film properties for tailored applications. The objective of this work is to investigate immersion time as a parameter to tune film properties and analyze the kinetics of LbL assembly. Multilayer films prepared using strong polycation poly (diallyldimethylammonium chloride) (PDDA) and strong polyanion poly (styrene sulfonate) (PSS), or the weak polyanion poly (acrylic acid) (PAA), and/or the synthetic clay Laponite were assembled using the solution dip LbL procedure. We also investigate the disassembly kinetics of these multilayers upon exposure to different pH conditions. UV-vis spectroscopy and AFM were used to measure the adsorption and desorption of polymers and film surface morphology. The kinetics of multilayer growth for strong polyelectrolyte system were observed to be different than for the weak polyelectrolyte system. Multilayer films of strong polyelectrolyte system of PDDA/PSS or clay system of PDDA/Laponite were found to be stable upon exposure to different pH conditions for very long times. LbL offers a convenient method to produce ultrathin films with nanometer scale control for various applications, e.g., drug delivery, optical coating, battery electrolytes and gas barriers.