Title: One-Step Fabrication of pH-Responsive Membranes and Microcapsules through Interfacial H-Bond Polymer Complexation,
Abstract: Biocompatible microencapsulation is of widespread interest for the targeted
delivery of active species in fields such as pharmaceuticals, cosmetics and
agro-chemistry. Capsules obtained by the self-assembly of polymers at
interfaces enable the combination of responsiveness to stimuli,
biocompatibility and scaled up production. Here, we present a one-step method
to produce in situ membranes at oil-water interfaces, based on the hydrogen
bond complexation of polymers between H-bond acceptor and donor in the oil and
aqueous phases, respectively. This robust process is realized through different
methods, to obtain capsules of various sizes, from the micrometer scale using
microfluidics or rotor-stator emulsification up to the centimeter scale using
drop dripping. The polymer layer exhibits unique self-healing and pH-responsive
properties. The membrane is viscoelastic at pH = 3, softens as pH is
progressively raised, and eventually dissolves above pH = 6 to release the oil
phase. This one-step method of preparation paves the way to the production of
large quantities of functional capsules.