We report on stimuli-responsive ultrathin polymer films and capsules with controlled pH-response properties and well defined mesh size, which have been fabricated via chemical crosslinking of hydrogen bonded layer-by-layer films. As surface-attached films, such hydrogels reversibly absorb and release large amounts of proteins in response to pH variations. As free-standing 3D structures (hollow capsules), they can encapsulate and controllably release a wide range of materials of various molecular weights, and show a distinct pH-dependent molecular sieving behavior. By varying the acidity and the chemistry of weak polyelectrolytes and/or neutral polymers, as well as the type of crosslinking, a high control of pH swelling including (1) the critical swelling pH, (2) the swelling amplitude; and (3) a complete switching swelling profiles in the pH scale can be achieved. The fine control over the response properties of such coatings enables their use in biomedical applications.