Hydrogen-Bonded Hybrid Multilayers: Film Architecture Controls Release of Macromolecules

Abstract

We report on the construction of purely hydrogen-bonded hybrid polymer multilayers, which are composed of polymer pairs with low- and high- pH stability, and show that the critical pH value of film deconstruction, fraction of components released, and the rate of film dissolution can be tuned in a wide pH range from 3 to 9.5 by varying film composition and architecture. The film building blocks were poly(N-vinylcaprolactam) (PVCL)/poly(l-aspartic acid) (PLAA) bilayers as pairs of hydrogen-bonded polymers with low pH stability (critical disintegration pH of ∼ 3.3), and poly(N-vinylcaprolactam) (PVCL)/tannic acid (TA) bilayers as hydrogen-bonded polymers with a higher critical disintegration pH of ∼9.5. Hybrid TA/PVCL/PLAA multilayers were prepared at low pH using a layer-by-layer technique. Film deposition and pH-induced deconstruction were followed by in situ Fourier transform infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) and phase-modulated ellipsometry. PVCL/TA and PVCL/PLAA pairs ...