pH-Programmable Sequential Dissolution of Multilayer Stacks of Hydrogen-Bonded Polymers.

We report that the interlayer diffusion of polymer chains within heterostructured hydrogen-bonded multilayer films depends on the stacking order: polymers diffuse more when high pH stability polymer pairs are assembled on top of low pH stability polymer pairs. By varying the stacking sequence, the fraction of the film that is released from the substrate can be tuned to achieve sequential pH-programmed release of the multilayer film. Also, we show that a multifunctional freestanding film with tunable film thickness can be generated by appropriate stacking and subsequent thermal cross-linking.