Novel Salt-Responsive SiO₂@Cellulose Membranes Promote Continuous Gradient and Adjustable Transport Efficiency

Abstract

Continuously growing interest in the controlled and tunable transport or separation of target molecules has attracted more attention recently. However, traditional "on−off" stimuli-responsive membranes are limited to nongradient feedback, which manifests as filtration efficiency that cannot be increased or decreased gradually along with the different stimuli conditions; indeed, only the transformation of on/off state is visible. Herein, we design and fabricate a series of robust salt-responsive SiO 2 @cellulose membranes (SRMs) by simply combining salt-responsive poly [3-(dimethyl(4vinylbenzyl)ammonium)propyl sulfonate] (polyDVBAPS)-modified SiO 2 nanoparticles and cellulose membranes under negative-pressure filtering. The antipolyelectrolyte effect induces stretch/shrinkage of polyDVBAPS chains inside the channels and facilities the directional aperture size and surface wettability variation, greatly enhancing the variability of interfacial transport and separation efficiency. Due to the linear salt-responsive feedback mechanism, the optimal SRMs achieve highly efficient target macromolecule separation (>75%) and rapid oil/saline separation (>97%) with a continuous gradient and adjustable permeability, instead of simply an "on−off" switch. The salt-responsive factors (SiO 2 -polyDVBAPS) could be reversibly separated or self-assembled to membrane substrates; thus, SRMs achieved unprecedented repeatability and reusability even after long-term cyclic testing, which exceeds those of currently reported membranes. Such SRMs possess simultaneously a superfast responsive time, a controllable gradient permeability, a high gating ratio, and an excellent reusability, making our strategy a potentially exciting approach for efficient osmotic transportation and target molecule separation in a more controllable manner.

Shaping Block Copolymer Microparticles by pH-Responsive Core-Cross-Linked Polymeric Nanoparticles

“…By grafting stimuli-responsive polymers to the inorganic NPs could make the NPs responsive to temperature, 37−39 pH, 33 and others. 40 These NPs could act as surfactants to shape the morphology of BCPs microparticles under 3D confinement in response to stimuli. 34 However, the grafting of polymer to the surface of inorganic NPs relied on special end groups which had strong attractive interaction to the NPs, making the synthesis of stimuli-responsive NPs difficult.…”

“…By grafting stimuli-responsive polymers to the inorganic NPs could make the NPs responsive to temperature, − pH, and others . These NPs could act as surfactants to shape the morphology of BCPs microparticles under 3D confinement in response to stimuli .…”

Recent Advances in Stimuli‐Responsive Smart Membranes for Nanofiltration

“…The membrane prepared by poly[3‐(dimethyl(4‐vinylbenzyl) ammonium) propylsulfonate] (PDVBAPS) modified SiO 2 nanoparticles has good salt response characteristics, which can achieve efficient target macromolecular separation (>75%) and rapid oil‐salt separation (>97%). [ 205 ] After exposure to a salt solution, the 2D effective filtration area decreased significantly and cations/counterions showed different permeability effects (Figure 9b). The anti‐electrolyte effect leads to the stretching/shrinking of the PDVBAPS polymer chain in the channel and promotes the change of directional pore size and surface wettability, greatly enhancing the change of interface transmission and separation efficiency.…”

Conductive Adhesive and Antibacterial Zwitterionic Hydrogel Dressing for Therapy of Full-Thickness Skin Wounds

“…In this work, we ingeniously introduce a new structural salt-responsive zwitterion poly[3-(dimethyl(4-vinylbenzyl) ammonium) propyl sulfonate] (SVBA) into the polyAAm network to extend the practical candidates for the field of wound healing. The nature of polySVBA chains previously already presented unique salt-responsive properties and was applied to bacterial release ( Zhang et al, 2018 ; Wu et al, 2019 ), selective oil/water separation ( Wang et al, 2020 ), and thermal-induced soft actuators ( He et al, 2019 ), etc. Interestingly, rigid aromatic backbone and sequential ionic interactions synergistically promote surface bonding, potential conductivity, matrix stretchability, and self-healing properties.…”