Dual-responsive zwitterion-modified nanopores: a mesoscopic simulation study.

In this work, dissipative particle dynamics simulation was carried out to investigate the intelligent switching effect of nanopores grafted by the zwitterionic polymer brushes poly(carboxybetaine) with excellent antifouling properties. The result shows that with different grafting densities and grafting lengths, zwitterionic polymer brushes show typical pH- and salt-responsiveness features. When the grafting density is greater than 0.2 accompanying a grafting length of 40, pH has a significant effect on the structure and pore size of the nanopores, that is, the pore remains open under neutral condition and exhibits a switching effect under acidic condition. Similarly, the size of the nanopore can be tuned by altering the grafting density and polymer chain length under salt-concentration-responsive conditions. Differently, compared with the pH effect, the salt concentration has an obvious impact on the switching effect, i.e. , responsiveness emerges with a lower grafting density and length. This work provides molecular level mechanism and theoretical guidance for the design of smart nanopores modified by zwitterionic polymer brushes, as well as plays an important role in the construction of nanopores with antifouling and pH/salt-responsive properties.