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A pH-Responsive Gating Membrane System with Pumping Effects for Improved Controlled Release


  • The National Natural Science Foundation of China (20206019, 50373029), the Trans-Century Training Programme Foundation for the Talented Scientists by the Ministry of Education of China (2002–48), Sichuan Youth Science and Technology Foundation for Distinguished Young Scholars (03ZQ026–41) and the Scientific and Technological Creation and Innovation Foundation of Sichuan University (2004CF06) are acknowledged for supporting this research. The authors are also grateful to X.-Y. Zhang at the Analytical and Testing Center of the Sichuan University for her help in the SEM observations.


In this study, we report on a novel composite membrane system for pH-responsive controlled release, which is composed of a porous membrane with linear grafted, positively pH-responsive polymeric gates acting as functional valves, and a crosslinked, negatively pH-responsive hydrogel inside the reservoir working as a functional pumping element. The proposed system features a large responsive release rate that goes effectively beyond the limit of concentration-driven diffusion due to the pumping effects of the negatively pH-responsive hydrogel inside the reservoir. The pH-responsive gating membranes were prepared by grafting poly(methacrylic acid) (PMAA) linear chains onto porous polyvinylidene fluoride (PVDF) membrane substrates using a plasma-graft pore-filling polymerization, and the crosslinked poly(N,N-dimethylaminoethyl methacrylate) (PDM) hydrogels were synthesized by free radical polymerization. The volume phase-transition characteristics of PMAA and PDM were opposite. The proposed system opens new doors for pH-responsive “smart” or “intelligent” controlled-release systems, which are highly attractive for drug-delivery systems, chemical carriers, sensors, and so on.

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