Abstract
Soft-matter materials research has considerably evolved in the last decades, mainly by promoting responsive 13 polymer systems. Up to now, the dynamic behavior in materials was always reached by the action of an outside 14 trigger (pH, light, etc..). This constraint has been relieved in a new class of materials that experienced self15 oscillation. In this work, the self-regulating pH cycles caused by a chemical oscillator will induce autonomous 16 pH-sensible polymer chain movements at the membrane interface, causing continuous pore-size oscillation 17 cycles and thus a self-oscillating flux. This work involved the functionalisation of polyethersulfone commercial 18 membranes to achieve pore size oscillations. The pH-sensitive polymer, poly(methacrylic acid) (PMAA), was 19 obtained by deprotection of poly(tert-butyl methacrylate) (PtBuMA) synthesized by RAFT polymerization. To 20 adapt this functionalisation to all types of commercial membranes, a thin layer of polydopamine (PDA) was 21 deposited on the top of the membrane, which then allows a Michael-thiol-ene reaction between PDA and thiol22 functionalised PMAA, obtained from prior aminolysis of PtBuMA. The functionalisation steps were 23 characterized by XPS, SEM, water contact angle, and permeability measurements. Membranes were then placed 24 in a filtration system containing a chemical pH oscillator to control the PMAA chain conformation through the 25 pH cycle. Water permeation analysis showed a dependence between permeability and PMAA conformation, 26 leading to the conclusion that there is indeed a continuous oscillation in membrane pore size.