Polymeric multilayer films comprising deconstructible hydrogen-bonded stacks confined between electrostatically assembled layers

Deconstructible polymeric films have potential applications in the areas of drug delivery, patterning, and membrane science. Here, we report on the preparation of heterogeneous multilayer films comprising alternate stacks of hydrogen-bonded (poly(4-vinylpyridine) (P4VP) and poly(acrylic acid, sodium salt) (PAA)) and electrostatically formed (poly(sodium 4-styrenesulfonate) (PSS) and poly(allylamine hydrochloride) (PAH)) layers via the layer-by-layer (LbL) assembly technique. We demonstrate that these polymeric films are highly pH sensitive toward deconstruction, with the onset of film deconstruction occurring at about pH 7.4. The pH-induced film deconstruction characteristics (total film loss and rate of deconstruction) depend on the number of hydrogen-bonded layers (PAA/P4VP)(n)/PAA inserted between stacks of PAH/PSS layers. Films containing a single hydrogen-bonded trilayer stack (n = 1) confined between PAH/PSS layers are stable up to pH 8.5, with only 15 wt % of the film desorbed at pH 10.3. Corresponding (nonconfined) PAA/P4VP films completely deconstruct (100% film loss) at this pH, indicating that the film deconstruction characteristics are closely related to the extent of physical confinement provided by the electrostatically assembled polyelectrolyte layers. Increasing the number of physically confined hydrogen-bonded layers in the film results in a systematic and significant increase in film loss from 15 (n = 1) to 83 wt % (n = 4) at pH 10.3. The current approach represents a facile means to tailor the deconstruction rates of polymeric multilayer films through the pH sensitivity of PAA/P4VP layers.