Abstract
Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Inspired by the stomatal closure feature of plant leaves at relatively high temperature, here we report a nano-gating membrane with a negative temperature-response coefficient that is capable of tunable water gating and precise small molecule separation. The membrane is composed of poly(N-isopropylacrylamide) covalently bound to graphene oxide via free-radical polymerization. By virtue of the temperature tunable lamellar spaces of the graphene oxide nanosheets, the water permeance of the membrane could be reversibly regulated with a high gating ratio. Moreover, the space tunability endows the membrane with the capability of gradually separating multiple molecules of different sizes. This nano-gating membrane expands the scope of temperature-responsive membranes and has great potential applications in smart gating systems and molecular separation.
Highlights
Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications
This biological phenomenon displays a negative temperature-response characteristic from a membrane perspective, that is, the membrane’s permeability decreases as the surrounding temperature increases[3,4,5]. This negative temperature-responsive phenomenon is prevalent in nature, most man-made temperature-responsive membranes have the opposite responsive trend where water permeability increases with increasing temperature, i.e., they show a positive temperatureresponse characteristic[6,7,8,9]. This is because most temperatureresponsive polymeric materials adopted in gating membranes undergo a coil-globule shrinking transition of their chains at a lower critical solution temperature (LCST)[10,11,12], and as a result, the membrane pores switch from a closed state below the LCST to an open state above the LCST
The temperature-responsive PNIPAM covalently grafted Graphene oxide (GO) membranes(P-GOMs) are based on regulating the layer spacing through tuning the molecular configuration of PNIPAM
Summary
Smart regulation of substance permeability through porous membranes is highly desirable for membrane applications. Negative temperature-response graphene-based membranes that can achieve water gating and molecular separation have never been reported. We construct a negative temperature-response nanogating membrane by covalently grafting poly(N-isopropylacrylamide) (PNIPAM) chains on GO sheets.
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