Magneto-responsive ultrafiltration membranes

Magneto-responsive ultrafiltration membranes

gassapng
 

Over the last few decades, stimuli-responsive membranes have attracted attention as they can self-regulate their permeability and selectivity properties in response to a specific stimulus such as pH, ions or temperature. Those smart membranes featuring dynamic properties have the potential to be utilized in advanced applications (e.g. drug delivery). However, to modify membrane’s intrinsic barrier properties, it is common to induce a response by changing conditions of the feed stream; this can make the utilization of such membranes inflexible, inefficient or even impossible. To solve this issue, this project focuses on the design of magneto-responsive ultrafiltration membranes featuring temporal and remote-controlled molecular sieving.

Based on previous works [1,2], we design magneto-responsive ultrafiltration membranes consisting of the pore filler poly(N-isopropylacrylamide) (PNIPAAm) as the thermo-responsive actuator and iron oxide nanoparticles (IONPs) as local heater. Triggered by high frequency alternating magnetic field (AMF), IONPs generate heat due to Néel relaxation and hysteresis loss, which is sufficient to evoke a phase transition in PNIPAAm. This transition is observed by deswelling of the polymer causing a shift of the molecular weight cut-off (MWCO). To obtain a large response in combination with dedicated selectivity and flux, it is crucial to optimize each building block (IONPs: heating efficiency; PNIPAAm: volume change) and their interaction within the membrane matrix as well as the porous polymeric membrane matrix itself. Our first approach is to design core-shell particles containing IONP cores covered with a thick PNIPAAm shell. If such particles are incorporated as gates in the barrier layer of the membrane, this shall cause a shift of the MWCO when exposed to an AMF. We expect that a direct contact of the local heater with the target actuator by core-shell formation maximizes the synergistic effect. Furthermore, the complexity of the membrane composition is reduced simplifying the control of the membrane structure during preparation by phase inversion processes.

References

  1. X. Lin, R. Huang, M. Ulbricht, J. Mater. Chem. B 2016, 4, 867
  2. X. Lin, B. Nguyen Quoc, M. Ulbricht, ACS Appl. Mater. Interf. 2016, 8, 29001

Contact:
Sanae Gassa