Layer-by-layer (LbL) assemblies, nanoscale films made from the alternate adsorption of oppositely charged species, have found widespread applications.  However, very little is known about the thermal behavior of LbL films. Therefore, it is pertinent to understand thermal properties such as Tg, physical aging, and thermal cross-linking, but these are often difficult to measure because LbL films can be very thin (few nm per layer). Here, the thermal properties of both dry and hydrated poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (PDAC/PSS) LbL assemblies assembled from solutions of varying ionic strength (0 to 1.25 M NaCl) are investigated using quartz crystal microbalance with dissipation (QCM-D) and modulated differential scanning calorimetry (MDSC). For the first time, thermal transitions such as Tg's can be measured for LbL assemblies using QCM-D by monitoring fluctuations in changes in dissipation, allowing us to probe the film's internal structure as a function of film depth.

Glass transitions of layer-by-layer assemblies determined using temperature-controlled quartz crystal microbalance with dissipation

244th National Meeting (2012)

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