Water structure and
dynamics can be key modulators of
adsorption,
separations, and reactions at soft material interfaces, but systematically
tuning water environments in an aqueous, accessible, and functionalizable
material platform has been elusive. This work leverages variations
in excluded volume to control and measure water diffusivity as a function
of position within polymeric micelles using Overhauser dynamic nuclear
polarization spectroscopy. Specifically, a versatile materials platform
consisting of sequence-defined polypeptoids simultaneously offers
a route to controlling the functional group position and a unique
opportunity to generate a water diffusivity gradient extending away
from the polymer micelle core. These results demonstrate an avenue
not only to rationally design the chemical and structural properties
of polymer surfaces but also to design and tune the local water dynamics
that, in turn, can adjust the local activity for solutes.