Development of polymer-based flooding technology to improve oil recovery efficiency, water dispersion copolymerization of acrylamide, cationic monomer methacryloxyethyltrimethyl ammonium chloride (METAC), and anionic monomer acrylic acid (AA) were carried out in aqueous ammonium sulfate solution with polyvinyl pyrrolidone (PVP) as the stabilizer. The copolymers were characterized by 1H-NMR, FT-IR, TG, and SEM to confirm that they were prepared successfully and exhibited excellent salt-resistant property. Moreover, the effect of the aqueous solution of ammonium sulfate (AS) concentration, stabilizer concentration, and initiator concentration on the viscosity and size were systematically investigated. To further improve the thermal endurance properties of copolymer, hydrophobic monomers with different alkyl chain lengths were added to the above system. The acrylamide-based quadripolymer possessed prominent thermal and salt endurance properties by utilizing the advantages of zwitterionic structure and hydrophobic monomer. With the temperature rising, the viscosity retention could reach 70.2% in the water and 63.8% in the saline. This work had expected to provide a new strategy to design polymers with excellent salinity tolerance and thermal-resistance performances.
Chinese herbal medicine has offered an enormous source for developing novel bio-soft materials. In this research, the natural polysaccharide isolated from the Chinese herbal medicine Dendrobium was employed as the secondary building block to fabricate a “hybrid” hydrogel with synthetic poly (vinyl alcohol) (PVA) polymers. Thanks to the presence of mannose units that contain cis-diol motifs on the chain of the Dendrobium polysaccharides, efficient crosslinking with the borax is allowed and reversible covalent borate ester bonds are formed. Eventually, highly dynamic and double-networked hydrogels were successfully prepared by the integration of Dendrobium polysaccharides and PVA. Interestingly, the introduction of polysaccharides has given rise to more robust and dynamic hydrogel networks, leading to enhanced thermal stability, mechanical strength, and tensile capacity (>1000%) as well as the rapid self-healing ability (<5 s) of the “hybrid” hydrogels compared with the PVA/borax single networked hydrogel. Moreover, the polysaccharides/PVA double network hydrogel showed selective antibacterial activity towards S. aureus. The reported polysaccharides/PVA double networked hydrogel would provide a scaffold to hybridize bioactive natural polysaccharides and synthetic polymers for developing robust but dynamic multiple networked hydrogels that are tailorable for biomedical applications.
Light-driven unidirectional molecular motors have gained significant attention since the pioneering work by Prof. Ben Feringa in 1999, and they hold great promise as next-generation smart materials. The intrinsic feature of point chirality and the helicity of these molecular motors requires efficient strategies to access their optically pure forms, especially when chirality-sensitive materials are fabricated. In this short review, we summarize synthetic strategies to access optically pure first- and second-generation molecular motors. Three general strategies are discussed: direct asymmetric synthesis, chiral auxiliary methods and chiral separation aided by a resolving agent. We hope that this review will ignite the enthusiasm of synthetic chemists to address very fundamental but unavoidable synthetic questions on chiral-alkene-based molecular motors concerning their large-scale applications.1 Introduction2 Synthesis of First-Generation Molecular Motors2.1 Direct Asymmetric Synthesis of Molecular Motors2.2 Resolving-Agent-Aided Chiral Resolution of Molecular Motors3 Synthesis of Second-Generation Molecular Motors3.1 Direct Asymmetric Synthesis of Molecular Motors3.2 Chiral Auxiliary Strategy3.3 Domino Strategy4 onclusions
With the increasing exploration and development of deep shale gas resources, water-based fracturing fluids face multiple challenges, including high-temperature resistance, salt tolerance, and efficient proppant transport. In this study, a zwitterionic polymer (polyAMASV) is synthesized via aqueous two-phase dispersion polymerization, using acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), acrylic acid (AA), stearyl methacrylate (SMA), and 4-vinylpyridine propylsulfobetaine (4-VPPS) as monomers. The introduction of hydrophobic alkyl chains effectively adjusts the viscoelasticity of the emulsion, while the incorporation of zwitterionic units provides salt tolerance through their intrinsic anti-polyelectrolyte effect. As a result, the solutions of such copolymers exhibit stable apparent viscosity in both NaCl and CaCl2 solutions and under high temperatures. Meanwhile, polyAMASV outperforms conventional samples across various saline environments, reducing proppant settling rates by approximately 20%. Moreover, the solutions exhibit rapid gel-breaking and low residue characteristics, ensuring effective reservoir protection. These results highlight the promising potential of polyAMASV for deep shale gas fracturing applications.
A novel supra-amphiphilic metallogelator [Cu12](OTf)2 having functional dibenzo-24-crown-8 as the hydrophilic part and complexed Cu2+/terpyridine as the hydrophobic part was prepared using an amphiphilic precursor. The supra-amphiphilic metallogelator was found to be able to gel in toluene/CH3CN or THF/CH3CN. The self-assembly mechanism of [Cu12](OTf)2 into a supramolecular gel was extensively studied by FT-IR, UV–Vis, fluorescence, PXRD spectroscopic techniques, and theoretical calculations, revealing that the intermolecular π–π interaction plays a vital role in the gel formation. Due to the presence of dibenzo-24-crown-8 and a coordinating terpyridine motif within the supra-amphiphilic metallogelator, the reversible gel–sol transition can be induced by several stimuli, including temperature, pH, mechanical force, and metal ion/competitive host molecules, making this supramolecular gel highly adaptive to the external environment. The work reported here offers prospects in the design of more metal-based supra-amphiphilic self-assembly building blocks by integrating the functions from both ligands and metal ions, opening new avenues for preparing multiple stimuli-responsive and adaptive materials.