Guangfa Zhang

Ultralow Oil-Fouling Heterogeneous Poly(ether sulfone) Ultrafiltration Membrane via Blending with Novel Amphiphilic Fluorinated Gradient Copolymers

A novel amphiphilic fluorinated gradient copolymer was prepared by semibatch reversible addition-fragmentation chain transfer (RAFT) method using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate (TFOA) as monomers. The resultant amphiphilic copolymers were then incorporated into the poly(ether sulfone) (PES) to fabricate PES blend membranes via the non-solvent-induced phase separation method (NIPS). During the phase inversion process, both hydrophilic (PEGMA) and low surface energy (TFOA) segments significantly enriched on the membrane surface by surface segregation to form an amphiphilic surface, which was demonstrated by surface wetting properties and X-ray photoelectron spectroscopy (XPS) measurements. According to the filtration experiments of oil-in-water emulsion, the heterogeneous membranes exhibited superior oil-fouling resistant properties, that is, low flux decay (as low as 15.4%) and high flux recovery (almost 100%), compared to the pure PES membrane. The synergistic effect of fouling-resistant and fouling-release mechanisms was found to be responsible for the excellent antifouling capacities. The findings of this study offer a facile and robust strategy for fabricating ultralow oil-fouling membranes that might be used for effective oil/water separation.

Enhanced oil-fouling resistance of poly(ether sulfone) membranes by incorporation of novel amphiphilic zwitterionic copolymers

In this study, a novel amphiphilic copolymer, poly(carboxyl betain methyl acrylamide-co-3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl acrylate) P(CBMA-co-TFOA), with zwitterionic and fluorinated moieties was synthesized by free radical polymerization and a subsequent quaternization reaction. The synthesized copolymers acted as additives and were blended with poly(ether sulfone) (PES) to fabricate low oil-fouling PES membranes through nonsolvent induced phase separation (NIPS). The prominent surface enrichment of hydrophilic zwitterionic (CBMA) and low surface energy (TFOA) segments on the membrane surface was verified by X-ray photoelectron spectroscopy (XPS), water contact angle measurements and surface energy analysis. The excellent oil-fouling resistant capacity of these modified membranes was demonstrated by oil/water emulsion separation tests. In particular, membrane PES/P3, with the optimized hydrophilic and hydrophobic ratio, achieved the highest anti-oil-fouling properties with a total flux decay as low as 17.4% (nearly no irreversible flux-decline) and high flux recovery (99.3%) after simple water flushing. These desirable antifouling properties are believed to originate from the binary-cooperative effect of zwitterionic and low surface energy microdomains. Moreover, three-cycle oil/water separation tests and underwater immersion experiments further revealed that the as-prepared membranes have remarkable antifouling stability. The results of this study provide a new insight into the surface chemical heterogeneity–antifouling property relationships of membranes for efficient oil/water separation.

Novel Fluorinated Polymers Containing Short Perfluorobutyl Side Chains and Their Super Wetting Performance on Diverse Substrates.

Because the emission of perfluorooctanoic acid (PFOA) was completely prohibited in 2015, the widely used poly- and perfluoroalkyl substances with long perfluoroalkyl groups must be substituted by environmentally friendly alternatives. In this study, one kind of potential alternative (i.e., fluorinated polymers with short perfluorobutyl side chains) has been synthesized from the prepared monomers {i.e., (perfluorobutyl)ethyl acrylate (C4A), (perfluorobutyl)ethyl methacrylate (C4MA), 2-[[[[2-(perfluorobutyl)]sulfonyl]methyl]amino]ethyl acrylate (C4SA), and methacrylate (C4SMA)}, and the microstructure, super wetting performance, and applications of the synthesized fluorinated polymers were systematically investigated. The thermal and crystallization behaviors of the fluoropolymer films were characterized by differential scanning calorimetry and wide-angle X-ray diffraction analysis, respectively. Dynamic water-repellent models were constructed. The stable low surface energy and dynamic water- and oil-repellent properties of these synthesized fluorinated polymers with short perfluorobutyl side chains were attributed to the synergetic effect of amorphous fluorinated side chains in perfluoroalkyl acrylate and crystalline hydrocarbon pendant groups in stearyl acrylate. Outstanding water- and oil-repellent properties of fabrics and any other substrates could be achieved by a facile dip-coating treatment using a fluorinated copolymer dispersion. As a result, we believe that our prepared fluorinated copolymers are potential candidates to replace the fluoroalkylated polymers with long perfluorinated chains in nonstick and self-cleaning applications in our daily life.

Facile fabrication of highly omniphobic and self-cleaning surfaces based on water mediated fluorinated nanosilica aggregation

Liquid repellent surfaces are being promisingly applied in industry and our daily lives. Herein we report a facile and effective sol–gel method for fabricating hybrid coatings with highly omniphobic and self-cleaning properties. The fluorinated hybrid nanocomposite was synthesized via one-step hydrolytic condensation of a nanosilica sol, methyltriethoxysilane (MTES) and 3-[(perfluorohexyl sulfonyl) amino] propyltriethoxysilane (HFTES). The solvent mixture of water and 2-propanol surrounding the hydrophobic nanosilica is a key factor in the control of nanoparticle aggregation, which leads to the formation of a multi-scale roughness surface with different wettabilities. The fluorinated nano-sol can be easily coated on various hard and soft substrates by spraying or dipping methods, endowing the substrate with omniphobicity to different organic liquids and biofoulings especially solidified egg white. Furthermore, the designed coating shows excellent self-cleaning and anti-adhesion properties in various harsh environments such as high temperature, acid and alkaline treatment and oil contamination. Owing to the facile method and its remarkable omniphobic abilities, the fluorinated hybrid coatings can be expected to have potential industry applications in a material system requiring robust antifouling, protein resistance and self-cleaning functions.

Polyols-Infused Slippery Surfaces Based on Magnetic Fe3O4-Functionalized Polymer Hybrids for Enhanced Multifunctional Anti-Icing and Deicing Properties

High durability, low cost, and superior anti-icing and active deicing multifunctional surface coatings, especially in the extreme environment, are highly desired to inhibit and/or eliminate the detriment of icing in many fields, such as automobile, aerospace, and power transmission. Herein, we first report a facile and versatile strategy to prepare novel slippery polyols-infused porous surfaces (SPIPSs) with the inexpensive polyols as the lubricant liquids. These SPIPSs are fabricated by a spray-coating approach based on amino-modified magnetic Fe3O4 nanoparticles (MNP@NH2) and amphiphilic P(poly(ethylene glycol) methyl ether methacrylate- co-glycidyl methacrylate) copolymer covalent cross-linked hybrids, followed by infusion with various polyols. The as-prepared surface exhibits excellent antifrosting property, that is, it can greatly postpone frost formation as long as 2700 s at -18 °C. Meanwhile, differential scanning calorimetry results clearly demonstrate that SPIPSs show a remarkable freezing point depression capacity and the crystallization point of water can be decreased as low as -36.8 °C. The SPIPS also displays an extremely low ice adhesion strength (0.1 kPa) due to its unique surface characteristics. Moreover, outstanding active thermal deicing property is achieved for these slippery surfaces because of intrinsically photothermal effect of magnetic Fe3O4 nanoparticle. Hence, these results indicate that this kind of multifunctional bioinspired slippery surface, with superb stability, good cost effectiveness, and easy fabrication, can be used as a promising candidate for anti-icing and deicing applications.