Zwitterion-Modified Thermoresponsive Polymers for Nanopore Applications: A Mesoscopic Simulation Study

In this work, dissipative particle dynamics simulations were used to study the intelligent "switching effect" of the hydrophilic nanopore modified with the zwitterionic polymer brushes consisting of poly(carboxybetaine methacrylate) (PCBMA) and poly(n-isopropylacrylamide) (PNIPAM). The results show that the PNIPAM polymer brushes show unique temperature-responsive characteristics under different grafting densities and grafting lengths. When the grafting density of the polymer brush covering the nanopores is moderate and the chain length is sufficient, the ambient temperature significantly influences the structure and pore size of the nanopores. Specifically, the nanopore remains in an "On" state at 323 K and an "Off" state at 293 K. Grafting the zwitterionic PCBMA onto the PNIPAM chain end could not only exhibit an excellent thermoresponsive "switching effect" and reversible stability, but also possess dual-responsive (temperature and pH) characteristics at high block ratios. When the temperature rises above the LCST, not only is the antifouling performance of the pure PNIPAM-grafted nanopores improved, but changing the solution pH also enables a "switching" effect across a broad range of block compositions. This study provides molecular-level mechanisms and theoretical insights for designing smart nanopores modified with zwitterionic and thermoresponsive block polymers, playing a crucial role in constructing nanopores with integrated antifouling and dual-responsive properties.