Facile Fabrication of CO2-Responsive Nanofibers from Photo-Cross-Linked Poly(pentafluorophenyl acrylate) Nanofibers

Scalable weaving of resilient membranes with on-demand superwettability for high-performance nanoemulsion separations

This study leverages the ancient craft of weaving to prepare membranes that can effectively treat oil/water mixtures, specifically challenging nanoemulsions. Drawing inspiration from the core-shell architecture of spider silk, we have engineered fibers, the fundamental building blocks for weaving membranes, that feature a mechanically robust core for tight weaving, coupled with a CO2-responsive shell that allows for on-demand wettability adjustments. Tightly weaving these fibers produces membranes with ideal pores, achieving over 99.6% separation efficiency for nanoemulsions with droplets as small as 20 nm. They offer high flux rates, on-demand self-cleaning, and can switch between sieving oil and water nanodroplets through simple CO2/N2 stimulation. Moreover, weaving can produce sufficiently large membranes (4800 cm2) to assemble a module that exhibits long-term stability and performance, surpassing state-of-the-art technologies for nanoemulsion separations, thus making industrial application a practical reality.

Scalable and switchable CO2-responsive membranes with high wettability for separation of various oil/water systems

Smart membranes with responsive wettability show promise for controllably separating oil/water mixtures, including immiscible oil-water mixtures and surfactant-stabilized oil/water emulsions. However, the membranes are challenged by unsatisfactory external stimuli, inadequate wettability responsiveness, difficulty in scalability and poor self-cleaning performance. Here, we develop a capillary force-driven confinement self-assembling strategy to construct a scalable and stable CO₂-responsive membrane for the smart separation of various oil/water systems. In this process, the CO₂-responsive copolymer can homogeneously adhere to the membrane surface by manipulating the capillary force, generating a membrane with a large area up to 3600 cm² and excellent switching wettability between high hydrophobicity/underwater superoleophilicity and superhydrophilicity/underwater superoleophobicity under CO₂/N₂ stimulation. The membrane can be applied to various oil/water systems, including immiscible mixtures, surfactant-stabilized emulsions, multiphase emulsions and pollutant-containing emulsions, demonstrating high separation efficiency (>99.9%), recyclability, and self-cleaning performance. Due to robust separation properties coupled with the excellent scalability, the membrane shows great implications for smart liquid separation.

CO2-responsive functional cotton fibers decorated with Ag nanoparticles for "smart" selective and enhanced dye adsorption

Novel Ag nanoparticles (NPs) decorated CO₂-responsive cotton fiber (PCCF@Ag) as eco-friendly adsorbent was prepared via in-situ growth of Ag NPs on the poly(2-(dimethylamino) ethyl methacrylate-co-4-acryloyloxybenzophenone) coated cotton fiber. The as-prepared PCCF@Ag displayed excellent adsorption performance toward both anionic and cationic dyes with or without CO₂ stimulation, even under a wide range of pH from 3 to 11. The maximum adsorption capacities of the as-prepared PCCF@Ag toward anionic dye (1538.5 mg g^-1 for MO) and cationic dyes (944.0 mg g^-1 for MEB and 415.6 mg g^-1 for NR) were satisfactory. The adsorption processes were described better by the Langmuir isotherm and pseudo-second-order kinetic models, respectively. Notably, upon CO₂ stimulation, the PCCF@Ag exhibited significantly enhanced adsorption capacity toward anionic dyes, following ultrafast adsorption rate, which made the PCCF@Ag could selectively adsorb anionic dyes from mixture because of greatly different adsorption rates between anionic dyes (adsorption equilibrium within 2 min) and cationic dyes (adsorption equilibrium over 12 h). Additionally, the PCCF@Ag could maintain over 91.0% of adsorption capacity even after ten cycles, indicating its outstanding reusability. Meanwhile, the as-obtained PCCF@Ag exhibited excellent antibacterial activity. Overall, the as-obtained PCCF@Ag could be considered as a promising dye scavenger for wastewater remediation.

Precision synthesis for well-defined linear and/or architecturally controlled thermoresponsive poly(N-substituted acrylamide)s

We describe the progress in precision polymerizations of specific kinds of N-alkylacrylamides and N,N-dialkylacrylamides to produce polymers showing thermoresponsive properties in aqueous media, which representatively include the reversible-deactivation radical polymerizations...

Recent Advances in Stimuli-Responsive Commodity Polymers

Known for their adaptability to surroundings, capability of transport control of molecules, or the ability of converting one type of energy to another as a result of external or internal stimuli, responsive polymers play a significant role in advancing scientific discoveries that may lead to an array of diverge applications. This review outlines recent advances in the developments of selected commodity polymers equipped with stimuli-responsiveness to temperature, pH, ionic strength, enzyme or glucose levels, carbon dioxide, water, redox agents, electromagnetic radiation, or electric and magnetic fields. Utilized diverse applications ranging from drug delivery to biosensing, dynamic structural components to color-changing coatings, this review focuses on commodity acrylics, epoxies, esters, carbonates, urethanes, and siloxane-based polymers containing responsive elements built into their architecture. In the context of stimuli-responsive chemistries, current technological advances as well as a critical outline of future opportunities and applications are also tackled.

Development of eco-friendly CO2-responsive cellulose nanofibril aerogels as "green" adsorbents for anionic dyes removal

A novel CO₂-responsive cellulose nanofibril aerogel as a "green" adsorbent derived from poly(methacrylic acid-co-2-(dimethylamino) ethyl methacrylate) and carboxylated cellulose nanofibrils was successfully prepared via stepwise cation-induced gelation and freeze drying method. This aerogel exhibited CO₂-triggered adsorption behavior towards anionic dyes with a rapid adsorption rate and a high adsorption capacity, as well as satisfactory mechanical properties. Upon CO₂ stimulation, the charged aerogel can selectively adsorb anionic dyes from aqueous solutions based on an electrostatic interaction. The maximum adsorption capacities of this aerogel towards methyl blue (MB), naphthol green B (NGB), and methyl orange (MO) were 598.8, 621.1 and 892.9 mg g^-1, respectively, accompanied by fast adsorption equilibriums towards MB and NGB within 7 min, and MO within 12 min. Meanwhile, the adsorption isotherms and the kinetics of the CO₂-responsive adsorbents followed the Freundlich isotherm and the pseudo-second-order model, respectively. Furthermore, the resulting CO₂-responsive adsorbent exhibited outstanding recyclability, as its adsorption performance can still be maintained even after twenty cycles. Accordingly, the resultant CO₂-responsive cellulose nanofibril aerogel could be a promising adsorbent material for the removal of anionic dyes in wastewater remediation.

Facile and Scalable Fabrication of Antibacterial CO2-Responsive Cotton for Ultrafast and Controllable Removal of Anionic Dyes

A novel CO₂-responsive cotton as an eco-friendly adsorbent derived from poly(4-acryloyloxybenzophenone-co-2-(dimethylamino) ethyl methacrylate) and cotton was fabricated via a facile and fast dip-coating method. As expected, upon CO₂ stimulation, the protonated cotton presented CO₂-induced "on-off" selective adsorption behaviors toward anionic dyes owing to electrostatic interactions. The adsorption isotherms and kinetics of the CO₂-responsive cotton toward anionic dyes obeyed the Langmuir isotherm and pseudo-second-order kinetics models, respectively. It is noteworthy that the CO₂-responsive cotton exhibited high adsorption capacity and ultrafast adsorption rate toward anionic dyes with the maximum adsorption capacities of 1785.71 mg g^-1 for methyl orange (MO), 1108.65 mg g^-1 for methyl blue (MB), and 1315.79 mg g^-1 for naphthol green B (NGB), following the adsorption equilibrium times of 5 min for MO, 3 min for MB, and 4 min for NGB. Moreover, the CO₂-responsive cotton also exhibited high removal efficiency toward anionic dyes in synthetic dye effluent. Additionally, the CO₂-responsive cotton could be facilely regenerated via heat treatment under mild conditions and presented stable adsorption properties even after 15 cycles. Finally, the as-prepared CO₂-responsive cotton exhibited outstanding antibacterial activity against E. coli and S. aureus. In summary, this novel CO₂-responsive cotton can be viewed as a promising eco-friendly adsorbent material for potential scalable application in dye-contaminated wastewater remediation.

Core-functionalized nanoaggregates: preparation via polymerization-induced self-assembly and their applications

Core-functionalized nanoaggregates can be prepared by a combination of polymerization-induced self-assembly (PISA) and post-polymerization modification.

A CO2-responsive hydrogel film for optical sensing of dissolved CO2

CO₂-monitoring plays an important role in medicine, environmental sciences, and food industries. Here, a new CO₂-responsive hydrogel film was fabricated from branched polyethyleneimine (BPEI) and partially oxidized dextran (PO-Dex) via layer-by-layer (LBL) assembly, based on the in situ Schiff base reaction between the two polymers. The swelling behaviours of the films were studied using Fabry-Perot fringes on their reflection spectra. Like ordinary hydrogels, the BPEI/PO-Dex films swell in water. In addition, they swell to a larger degree when CO₂ is introduced, due to the reaction between CO₂ and the amino groups in BPEI. The CO₂-induced swelling can be reported by the shift of the Fabry-Perot fringes on their reflection spectra; therefore, the BPEI/PO-Dex film can be used as an optical sensor for dissolved CO₂. In the new sensor, the BPEI/PO-Dex film acts as a CO₂-sensing material and Fabry-Perot cavity simultaneously. The introduction of ordered structure is no longer required. The response of the sensor to CO₂ is linear and reversible. Unlike other hydrogel-based sensors that suffer from a slow response, the new sensor can respond to CO₂ quickly, making it applicable for real-time, continuous monitoring of CO₂ levels in solution.