Protein-resistance performance enhanced by formation of highly-ordered perfluorinated alkyls on fluorinated polymer surfaces

Engineering of Graphdiyne-Based Functional Coatings for the Protection of Arbitrary Shapes of Copper Substrates

Copper-based materials are very important for many application fields from marine industry to energy management and electronic devices. For most of these applications, the copper objects require long-term contact to a wet and salty environment, which leads to serious corrosion of copper. In this work, we report a thin graphdiyne layer directly grown on arbitrary shapes of copper objects at mild conditions, which could function as a protective coating for the copper substrates in artificial seawater with corrosion inhibition efficiency of ∼99.75%. To further improve the protective performance of the coating, the graphdiyne layer is fluorinated and followed by infusion with a fluorine-containing lubricant (i.e., perfluoropolyether). As a result, a slippery surface is obtained, which shows enhanced corrosion inhibition efficiency of ∼99.99% as well as excellent antibiofouling properties against microorganisms, such as protein and algae. Finally, the coatings are successfully applied in the protection of a commercial copper radiator from long-term attack of artificial seawater without disturbing its thermal conductivity. These results demonstrate the great potential of graphdiyne-based functional coatings for the protection of copper devices in aggressive environments.

Construction strategies and the development trend of antibacterial surfaces

The construction of antibacterial surfaces is an efficient way to respond to the problem of microbial contamination. In this review, we first describe the formation process and characteristics of microbial contamination and the current research status of antibacterial surfaces. Then, the passive antiadhesion, active killing, and combination construction strategies of the antibacterial surface are discussed in detail. Based on different antibacterial mechanisms and existing problems of current antibacterial strategies, we then discuss the future development trends of the next generation of antibacterial surfaces.

Small microplastics (<100 μm), plasticizers and additives in seawater and sediments: Oleo-extraction, purification, quantification, and polymer characterization using Micro-FTIR

In this study, the abundance and the distribution of small microplastics (<100 μm, SMPs) and of other components of micro-litter (i.e., additives, plasticizers, natural and non-plastic synthetic fibers, APFs) were investigated in sediments and seawater of three different sites of a transitional environment; different anthropogenic impacts and environmental features characterize these three sites. The pretreatment method developed (oleo-extraction and purification procedures) allowed the collection of particles (SMPs and APFs) in a wide range of densities, e.g., from low-density plastics to high-density plastics, avoiding further degradation/denaturation of polymers. An analytical method for quantification and simultaneous identification of SMPs and APFs via Micro-FTIR was developed. Higher abundances of SMPs were observed in sediments compared to the abundance observed in seawater. SMPs were not the major component of the micro-litter. With natural fibers and non-plastic fibers, additives and plasticizers were quantified and identified in sediments and seawater. These latter are employed to obtain specific characteristics of polymers; hence their presence can be a good proxy of these polymers' presence in the environment. Sources and pathways may influence the abundance and distribution of SMPs and APFs. Differences in abundance and distribution of these pollutants in sediments and seawater of the three sites investigated were statistically significant.

Surface Fluorination Modification and Anti-Biofouling Study of a pHEMA Hydrogel

A poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogel film was prepared by bulk polymerization. Then, it was surface modified by perfluorooctanoyl chloride to improve the anti-biofouling properties. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDXS), and atomic force microscopy (AFM) analyses demonstrated that the uniform dense fluorinated layer had been successfully grafted onto pHEMA. The water contact angle (WCA) of the modified pHEMA film increased to 135°, while the surface energy decreased to 13.32 mN/m. The protein and bacterial adhesion properties of the modified pHEMA were decreased significantly. The in vitro cytotoxicity showed that the modified pHEMA was noncytotoxic. Thus, the fluorinated modification on the material surface was a convenient and effective method to establish a hydrophobic and anti-biofouling surface.

Diblock Polymer Brush (PHEAA- b-PFMA): Microphase Separation Behavior and Anti-Protein Adsorption Performance

In this paper, a series of amphiphilic diblock polymers of poly(hydroxyethylacrylamide)- b-poly(1H,1H-pentafluoropropyl methacrylate) (PHEAA- b-PFMA) were grafted from silicon wafer via surface-initiated atom transfer radical polymerization (SI-ATRP). Surface wettability and chemical compositions of the modified surfaces were characterized by contact angle goniometer and X-ray photoelectron spectroscopy (XPS) respectively. Molecular weight and polydispersity of each block were measured using gel permeation chromatography (GPC). The topography and the microphase separation behavior of PHEAA- b-PFMA surfaces were investigated by atomic force microscope (AFM). The results show that only when the grafting density (σ) and thickness of PHEAA brush were in the range of 0.9-1.3 (chain/nm²) and 6.6-15.1 nm, respectively, and the ratio of PFMA/PHEAA varied from 89/42 to 89/94, could the diblock copolymer phase separate into nanostructures. Further, the antiprotein adsorption performance of the modified surfaces against BSA, fibrinogen, and lysozyme was studied. The results indicated the modified surfaces could reduce the protein adsorption compared to the pristine silicon wafer. For Fibrinogen, the antiadsorption effect of PHEAA- b-PFMA-modified surfaces with microphase segregation was better than that of corresponding PHEAA modified surfaces. The results provide further evidence that surface composition and microphase segregation of fluorinated moieties of block copolymer brushes significantly impact protein adsorption behaviors.

Preparation of chitin-amphipathic anion/quaternary ammonium salt ecofriendly dressing and its effect on wound healing in mice

Objective

This study aimed to prepare an eco-friendly dressing using a chitin-derived membrane with amphipathic anion/quaternary ammonium salt designed for antibacterial purposes.

Methods

Four dressings were prepared and group A was chitin, group B was chitin + amphiphilic ion, group C was chitin + quaternary ammonium salt, group D was chitin + amphiphilic ion + quaternary ammonium salt.

Results

In the group D material, precipitation of adherent composite ions was observed. The contact angle test showed that the material was hydrophilic. The drug loading rate in groups B, C, and D was 40-50 (ug:mg), the entrapment efficiency was 70%-75% (P>0.05), and the cumulative release percentages were 87.3%, 88.7%, and 90.2% after 72h for group B, C, and D, respectively. The anti-bacterial activity in vitro was in the order D>C>B>A> control (P>0.05). The anti-pollution activity in vitro was in the order D>B>C>A (P<0.05). The cell proliferation inhibition test showed slight proliferation inhibition (P<0.05) only on the seventh day for group D. Seven days after injury, the wound healing rate was in the order D>C> commercial chitin dressing >B>A> control (P<0.05), and the length of the neonatal epithelium also showed the same trend. Additionally, PCNA and CD31 expression indicated that cell proliferation and angiogenesis were enhanced when skin defects were covered with the D group material (P<0.05).

Conclusion

chitin-amphiphilic ion/quaternary ammonium salt dressing was successfully prepared. The antibacterial and antipollution effects of the prepared material (group D) were both very good, acting to promote wound healing.

Toward Achieving Highly Ordered Fluorinated Surfaces of Spin-Coated Polymer Thin Films by Optimizing the Air/Liquid Interfacial Structure of the Casting Solutions

Thin polymer films with well-assembled fluorinated groups on their surfaces are not easily achieved via spin-coating film-fabrication methods because the solution solidifies very rapidly during spin-coating, which hinders the fluorinated moieties from segregating and organizing on the film surface. In this contribution, we have proposed a comprehensive strategy toward achieving well-ordered fluorinated thin films surfaces by optimizing the molecular organization at air/liquid interface of the film-formation solutions. To validate such a route, poly(methyl methacrylate) (PMMA) end-capped with several 2-perfluorooctylethyl methacrylate (FMA) units was employed as the model polymer for investigations. The air/solution interfacial structures were optimized by systematically changing the polymer chain structures and properties of the casting solvents. It was found that the polymers that form loosely associated aggregates (e.g., FMA₁- ec-PMMA₆₅- ec-FMA₁) and a solvent with better solubility to FMA while having not too low surface tension (i.e., toluene) can combine to produce solutions with well-assembled FMA at the interfaces. By spin-coating the solutions with well-organized interfaces, an ultrathin film with perfluorinated groups that were highly oriented toward the film surface was readily achieved, exhibiting surface energies as low as 7.2 mJ/m², which is among the lowest reported so far for the spin-coated thin films, and a very high F/C ratio (i.e., 0.98).

Membranes with Surface-Enhanced Antifouling Properties for Water Purification

Membrane technology has emerged as an attractive approach for water purification, while mitigation of fouling is key to lower membrane operating costs. This article reviews various materials with antifouling properties that can be coated or grafted onto the membrane surface to improve the antifouling properties of the membranes and thus, retain high water permeance. These materials can be separated into three categories, hydrophilic materials, such as poly(ethylene glycol), polydopamine and zwitterions, hydrophobic materials, such as fluoropolymers, and amphiphilic materials. The states of water in these materials and the mechanisms for the antifouling properties are discussed. The corresponding approaches to coat or graft these materials on the membrane surface are reviewed, and the materials with promising performance are highlighted.

Antibacterial and biocompatible ABA-triblock copolymers containing perfluoropolyether and plant-based cardanol for versatile coating applications

ABA-triblock copolymers were prepared via ATRP, using modified perfluoropolyether (PFPE) as a macroinitiator (Br–PFPE–Br) to form the B block, and 2-hydroxy-3-cardanylpropyl methacrylate (HCPM) as a monomer to form the A blocks.

Fabrication of polymer brush surfaces with highly-ordered perfluoroalkyl side groups at the brush end and their antibiofouling properties

The protein-resistant performance was enhanced greatly by constructing a polymer brush surface with perfectly close-packed perfluoroalkyl groups.

Non-toxic, non-biocide-release antifouling coatings based on molecular structure design for marine applications

Antifouling (AF) coatings bring economic benefits but raise environmental and health concerns. Non-toxic, non-biocide-release AF strategies are reviewed according to “detachment of biofoulants” and “prevention of attachment” approaches. Chemical and physical aspects of AF mechanisms and new amphiphilic, superhydrophilic and topographic AF strategies are discussed.

Protein-resistance performance of amphiphilic copolymer brushes consisting of fluorinated polymers and polyacrylamide grafted from silicon surfaces

A series of random copolymer brushes of acrylamide (AM) and 2-(perfluorinated hexyl)ethyl methacrylate (FMA) were grafted from initiator-functionalized silicon wafers by surface-initiated atom transfer radical polymerization.

Effect of surface compositional heterogeneities and microphase segregation of fluorinated amphiphilic copolymers on antifouling performance

In this paper, a series of fluorinated amphiphilic copolymers composed of 2-perfluorooctylethyl methacrylate (FMA) and 2-hydroxyethyl methacrylate (HEMA) monomers were prepared, and their surface properties and antifouling performance were investigated. Bovine serum albumin (BSA) and human plasma fibrinogen (HFg) were used as model proteins to study protein adsorption onto the fluorinated amphiphilic surfaces. All the fluorinated amphiphilic surfaces exhibit excellent resistant performance of protein adsorption measured by X-ray photoelectron spectroscopy (XPS). The surface compositional heterogeneities on the molecular scale play an important role in the antifouling properties. It was found that the copolymers exhibited better antifouling properties than the corresponding homopolymers did, when the percentage of hydrophilic hydroxyl groups is from 4% to 7% and the percentage of hydrophobic fluorinated moieties is from 4% to 14% on the surface. In addition, the protein molecular size scale and the pattern of microphase segregation domains on the surface strongly affect the protein adsorption behaviors. These results demonstrate the desirable protein-resistant performance from the fluorinated amphiphilic copolymers and provide deeper insight of the effect of surface compositional heterogeneity and microphase segregation on the protein adsorption behaviors.