Bioinspired graphene membrane with temperature tunable channels for water gating and molecular separation

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.

Role of Interface Interactions in the Construction of GO‐Based Artificial Nacres

“…The interface in the nacre induces multiple toughening mechanism, such as mineral bridging, nanoasperities shearing, organic gluing, and tablet interlocking, [1] as shown in Figure 3. [122][123][124][125][126][127][128] In addition, different interface interactions could be reasonably combined to result in synergistic effect, [111,[129][130][131][132][133][134][135][136][137][138][139] which is similar to the multiple interface interactions in nacre. [48,75,[91][92][93][94] The interfacial crosslinking strategies contain hydrogen bonding, [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113][114] ionic bonding, …”

“…[48,75,[91][92][93][94] The interfacial crosslinking strategies contain hydrogen bonding, [95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112][113][114] ionic bonding, [81,[115][116][117][118] π-π interaction, [119][120][121] and covalent bonding. Besides providing excellent mechanical properties, the addition of functional building blocks and crosslinkers also endows the GANs other functions, such as fatigue resistance, [58,133,144] fire retardant property, [142] and smart nanogating, [128] etc. On the other hand, the second building block, which contains 1D nanofibrils, such as nanofibrillar cellulose (NFC), [140] and CNTs, [141] etc., and 2D nanoplatelets, such as MMT, [142] molybdenum disulfide (MoS 2 ), [143] and tungsten disulfide (WS 2 ) nanosheets, [144] etc., could also be incorporated to induce synergistic toughening effect.…”

“…Figure 4 shows representative high performance GANs strengthened by single interface interaction. [128] 3. Generally, the tensile strength of GANs is mainly associated with the interfacial strength and crosslinking density, while the toughness mostly depends on the plastic deformation of crosslinkers.…”

“…Recently, Liu et al [128] covalently grafted poly(N-isopropylacrylamide) (PNIPAM) on the GO nanosheets www.advmatinterfaces.de to fabricate strong and negative temperature-response nanogating GANs. Recently, Liu et al [128] covalently grafted poly(N-isopropylacrylamide) (PNIPAM) on the GO nanosheets www.advmatinterfaces.de to fabricate strong and negative temperature-response nanogating GANs.…”

Smart Nacre‐inspired Nanocomposites

“…Other than the actuation, the layered structure with abundant tunable nanoscale channels also confers GO‐based film nanocomposites with responsive function of molecule sieving . Liu et al . fabricated a GO‐based film nanocomposites with poly(N‐isopropylacrylamide) (PNIPAM), which can be used as a smart gating for molecule sieving triggered by temperature variation or NIR light.…”