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The development of microorganisms and formation of thrombus on a biomaterial surface can seriously lead to device failure and threaten human health. Nonetheless, a surface that has both antibacterial and anticoagulant properties has scarcely been developed. Herein, a novel dual-action membrane composed of polyethersulfone (PES) bulk material and a hydrophilic anionic poly-2-acrylamido-2-methylpropanesulfonic acid (PAMPS) polymer has been prepared via the cationic antibacterial agent poly(hexamethylene biguanide) (PHMB)-induced phase separation technique. Interestingly, the resultant membrane can offer tunable antibacterial and anticoagulant properties, while maintaining satisfactory permeability and greatly increasing selectivity. The membrane also shows excellent hydrophilicity, a well-defined porous surface, and cross section with a sponge gradient structure. Furthermore, the PHMB-PAMPS complex formed on the membrane surface displays outstanding long-term stability, which is crucial for further practical applications. More importantly, the hollow fiber membrane fabricated by the cationic polyelectrolyte-induced phase separation technique confirms its capability to control the membrane permeability (257.4 L·m-2·h-1·bar-1) and selectivity (95.9%) without destroying the membrane structure. The present work opens a straightforward and efficient avenue for the rational design of a functional surface to fight biomedical material-associated infections.

In recent years, natural polymer-based electrospun fibers (EFs) with huge specific surface area, good biocompatibility, and biological activity obtained from electrospinning process exhibit tremendous vitality in the field of biomedical areas. Herein, the parameters of electrospinning from two perspectives, polymer solution such as solvent, polymeric relative molecular mass, concentration, viscosity, and conductivity of the solution, and electrospinning process such as spinning voltage, spinning flow rate, needle tip to collector distance, temperature, and humidity are first detailed. Next, the raw materials consisting of polysaccharides such as cellulose, hyaluronic acid, alginate, and chitosan as well as proteins such as collagen, gelatin, silk fibroin, and keratin are summarized. The preparation method and related characteristics of EFs with multistage structures such as porous, core-shell, Janus, bamboo-like and other structures are introduced. The biomedical applications of these natural polymer-based EFs mainly including tissue engineering, drug sustained release, wound dressings, and biomedical sensors are systematically recapitulated. Finally, the outlook on natural EFs is further proposed.

Summary Maintaining the superhydrophobicity underwater offers drag resistance reduction, antifouling, anti-corrosion, noise reduction, and gas collection for boat hulls and submarine vehicles. However, superhydrophobicity typically does not last long underwater since the Cassie state is metastable. Here, we report a reversible and localized recovery of superhydrophobicity from the fully wetted state via air bubble spreading. Composed of sparse fluorinated chained nanoparticles, the submerged surface shows super-low energy barrier for bubble attachment. Especially the recovered plastron exhibits excellent longevity. Based on a simplified, truncated nanocone model, the dynamic spreading of bubbles is analyzed considering two basic parameters, i.e., surface geometric structure and surface energy (which appeared as intrinsic water contact angle). Numerical simulation results via COMSOL confirms the effect of geometric structure on bubble spreading. This investigation will not only offer new insights for the design of robust recoverable superhydrophobic surfaces but also broaden the applications of superhydrophobic coatings., Graphical abstract, Highlights • Superhydrophobicity is recovered from fully wetted state in submerged system • The dynamic spreading of bubbles is theoretically analyzed • The geometric criteria provide direction in designing superhydrophobic surfaces, Surface chemistry; Materials science; Nanomaterials

Biofouling as a global problem has made detrimental impact on many fields, especially for marine industry. Polydimethylsiloxane-based coatings are environment-friendly and exhibiting good fouling release performance in the marine coating application. However, their intrinsic low surface energy and high hydrophobic character lead to poor fouling resistance property and weak adhesion to substrate. In this work, we firstly fabricate self-adhesive PDMS-based amphiphilic cross-linked coatings with good anti-biofouling performance via synthesizing dopamine methacrylamide which then copolymerized with mercaptopropyl methylsiloxane- dimethysiloxane, poly (ethylene glycol) diacrylate under UV photo-cross-linking. The coating exhibits devisable heterogeneous nanoscale mosaic chemical surfaces caused by micro phase segregation, effectively resistance to nonspecific protein adsorption and marine fouling organism (P. tricornutum) attachment which are mainly ascribed to the unique surface topography and chemical heterogeneity. Moreover, the resulting coatings exhibit significantly improved adhesion to substrates, due to complex interfacial catechol chemistry reaction. This simple design provides a novel methodology for preparing an efficient and eco-friendly anti-biofouling PDMS-based amphiphilic coating.

Conventional thin-film composite forward osmosis membrane suffers from serious biofouling problem when used for desalination and treating wastewater. However, reported improved strategies are difficult to keep a balance between fouling resistance and membrane performance. To address this challenge, this work presents a simple and efficient surface modification strategy to construct a zwitterion-silver nanocomposite structure via second interfacial polymerization of zwitterion and in situ synthesis of silver nanoparticles (Ag NPs), which improves the polyamide layer in terms of hydrophilicity and transport properties without adversely affecting the selectivity. In addition, the zwitterion-silver modified membrane exhibits significantly biofouling resistance due to the simultaneous improvement of antiadhesive and antimicrobial property. Furthermore, the zwitterion-silver modified membrane with regeneration ability shows a long-term anti-biofouling property. Compared with other reports, the zwitterion-silver nanocomposite modified membrane shows outstanding antifouling property (>96% antimicrobial efficiency), high water flux and excellent selectivity, which highlights its potential for practical applications.

In this work, polyethersulfone (PES) membranes with superior antifouling and anticoagulant properties were prepared effectively and efficiently through the non-solvent induced phase separation (NIPS) method via in situ copolymerization mediated surface zwitterionicalization. Glycidyl methacrylate (GMA) was copolymerized with poly(ethylene glycol)methyl ether methacrylate (PEGMA) in the casting solution to form amphiphilic P(GMA-r-PEGMA), which not only enhanced the hydrophilic properties of PES membranes but also provided the active chemical sites for the immobilization of zwitterionic lysine on the membrane surface. Upon modification, the membranes exhibited suppressed protein adsorption, improved wettability, better antifouling and anticoagulant abilities (suppressed platelet adhesion, a prolonged plasma clotting time and improved hemolytic activity) compared to the virgin PES membrane. The water contact angle of the modified membranes was decreased to as low as 37° while the flux recovery ratio was increased to as high as 99.1%. This work provided an effective and efficient way for the fabrication of low fouling membranes without adding any additional steps to the process of membrane formation.

Non-polyamide composite nanofiltration (NF) membranes based on N-methyl- d -glucamine (NMG)-assisted polydopamine (PDA) coating were prepared by a simple deposition process followed by glutaraldehyde crosslinking, which showed excellent structural stability so as to solve the problem as encountered by commercial NF membrane. The addition of NMG promoted the deposition and polymerization of dopamine to form a dense and homogeneous selective layer with improved hydrophilicity in a time-saving mode. The composite membranes under optimal conditions exhibited high pure water flux of 10.29 L m− 2 h− 1 bar− 1, high organic dye rejection of over 99.0% and high Na2SO4 rejection of 81.2%. Particularly, as compared with the previously reported commercial NF membranes, one big advantage for high NaCl permeation was presented, due to low NaCl rejection with narrow range under the filtering process of different salt concentrations. Furthermore, 24 h continuous filtration experiment using mixtures of acid red 18 and NaCl showed low salt rejection ( 99.0%), indicating that the composite membranes have potential for dye/salt fractionation. Apart from providing a new candidate membrane for dye/salt fractionation, the successful development of structure-stable polydopamine-based NF membrane is expect to speed up the paces toward practical applications of non-polyamide membranes in the near future.

Hybrid polyvinylidene fluoride (PVDF) ultrafiltration membranes were prepared using hollow silica microspheres (HSiO2) as an extraordinary additive. The results showed that HSiO2 microspheres had inner cavity structure, mesoporous wall, good dispersion and excellent hydrophilicity, and could be used to construct stepped permeable channels for decreasing the mass transfer resistance of water molecules in the porous support layer of PVDF membrane. The improved hydrophilicity and constructed channels of PVDF matrix by added HSiO2 improved the separation and antifouling performance of hybrid PVDF membrane, which were conducive to increase the separation efficiency and prolong the service life of membrane module.

In this work, antifouling poly(vinylidene fluoride) (PVDF) microfiltration membrane was fabricated via surface activation by atmosphere plasma treatment and subsequently surface-initiated atom transfer radical polymerization (SI-ATRP). Zwitterionic poly(lysine methacrylamide) (LysAA) brushes were successfully grafted onto membrane surface as confirmed by Fourier-transform infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS). The wetting ability of the graft membranes was improved significantly with water contact angle decreased from 121.6° to as low as 29.0°. The graft membranes also exhibited enhanced anti-protein-fouling and anti-oil-fouling properties with water flux recovery ratios as high as 86% and 82% respectively. This work provides a substrate-independent method for the fabrication of antifouling membranes with well-defined pLysAA brushes, which may find applications in protein separation, water treatment and oil/water separation, etc.

A series of antibiofouling amphiphilic conetwork (APCN) coatings combined with zwitterionic features are engineered by surface zwitterionization of spontaneously segregated poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) segments, where this dual-mode surface integration of both passive and active modes improves the entire antifouling efficiency against the adsorption of proteins and a widespread marine fouling organism (Phaeodactylum tricornutum). A clear difference in surface morphology and topography before and after surface zwitterionization is ascribed to the transformation of PDMAEMA to carboxlbetaine zwitterion, which promotes the phase segregation and simultaneously accelerates the migration of hydrophilic segments toward the surface. The surface morphology evolved with hydrophilic content, and the variation trend of surface roughness before and after surface zwitterionization is exactly opposite under different hydrophilic content. With regard to structure–antibiofouling relationships, the zw...

A novel zwitterionic surface of PVDF membrane with significantly improved antifouling properties was prepared though pressure-assisted layer by layer self-assembly method based on the electrostatic interactions of chitosan (CS), sodium alginate (SA) and polyfunctional lysine. For the modified C-S-C-S-L membrane, the contact angle decreased to 35°, the bovine serum albumin (BSA) adsorption mass of static fouling on the membrane surface decreased to 10μg/cm(2), and the secondary water flux recovery rate (FRR) of dynamic fouling of BSA and humic acid (HA) pollutants increased to 98% and 99%, respectively, exhibiting excellent antifouling performance. The results demonstrated that using charged bio-macromolecules and amino acids to build zwitterionic surface was effective and convenient to change the interface properties of the separation membrane through the pressure-assisted self-assembly modification method, and provided a new way for the industrial scale hydrophilic modification of hydrophobic porous membrane materials.

The polydimethylsiloxane modified silica (SiO2-g-PDMS) nanoparticles with hydrophilic core and hydrophobic shell are employed for the hybridization modification of PVDF ultrafiltration membrane to improve the separation and antifouling performances. The results suggest the modified SiO2-g-PDMS nanoparticles exhibit improved dispersion and significant amphiphilic characteristics, and the wetting properties of membrane surface and mimetic matrix of hybrid PVDF membranes are distinctly different with the contact angle values at 105° and 15°, respectively. In addition, the added SiO2-g-PDMS nanoparticles significantly improve the fouling repulsion and fouling release properties of hybrid PVDF membranes, the anti-adsorption ability and water flux recovery ratio (FRR-W) of hybrid PVDF membranes to the two typical pollutants of bovine serum albumin (BSA) and humic acid (HA) have been significantly improved. This article aims to provide a simple way to improve the antifouling performance of PVDF ultrafiltration membrane with dual-mode multi-functional modifier.

Membrane fouling is one of the major challenges facing widespread application of membrane technology, and antifouling membranes have the advantages of increased production capacity and decreased operation costs. In this work, polyethersulfone membrane with superior antifouling property was fabricated through the facile blending of a dual-mode amphiphilic copolymer, poly(N-methyl-D-glucamine)-block-polydimethylsiloxane-block-poly(N-methyl-D-glucamine) (PNMG-b-PDMS-b-PNMG). Surface enrichment of the amphiphilic copolymer was expected to occur during the coagulation step of the phase inversion process, which endowed the modified membranes with dual-mode antifouling ability of fouling repulsion and fouling release. Filtration experiments showed that water flux and BSA solution flux of the blend membranes were significantly enhanced. The blend membranes also showed improved antifouling properties with flux recovery ratio as high as 97 % after three cycles of BSA filtration. These results provide an effective way for the preparation of low-fouling membrane in the fields of water treatment, protein separation, and blood purification.

Natural heparin macromolecule has been widely used to improve the hemocompatibility of biomaterials. However, heparin can cause spontaneous bleeding in some patients, which is troublesome for clinical applications. Fortunately, analogous heparin polymers have shown promise to replace heparin. Here a new class of composite polyethersulfone (PES) membranes were constructed, which offered tunable permeability together with excellent hemocompatibility via incorporating heparin-mimicking semi-interpenetrating polymer. The polyurethane macromer was synthesized as an effective cross-linker to incorporate functional polyacrylic acid and poly-2-acrylanmido-2-methylpropanesulfonic acid segments into PES solution through in-situ cross-linking polymerization. Then the heparin-mimicking semi-interpenetrating composite PES membranes were fabricated from the resulting casting solution via alkali-induced phase separation technique. The resulting composite membranes showed excellent inhibition of protein adsorption, suppression of platelet adhesion, reduction of hemolysis ratio and prolongation of clotting times, while displayed high hydrophilicity, permeability and clearance to urea, creatinine and lysozyme. Interestingly, the composite membranes also exhibited excellent mechanical properties due to the synergistic effect of polyurethane composition and in-situ cross-linking copolymerization. To further demonstrate the applicability and effectiveness of this method, a composite PES hollow fiber with excellent ultrafiltration and mechanical properties was also fabricated. This straightforward and facile method is constructed as an ideal candidate to suppress blood clotting for a range of blood purification membrane-related applications.

Although zwitterionic polymers exhibit outstanding non-fouling property and biocompatibility, their poor solubility in organic solvents limits their practical applications. In this work, an amphiphilic zwitterionic polymer whose core is made of PES matrix was designed via addition and quaternization, which exhibited excellent solubility in various organic solvents and good compatibility with PES. Its incorporation into the PES matrix by direct blending endowed the resulting membrane with excellent hydrophilicity and high water flux (243.4 L m−2 h−1), which was amplified about 2 times that of the pure PES membrane (125.0 L m−2 h−1), and the flux recover ratio was as high as 93.8%. Especially, the hemocompatibility of membranes determined by the protein adsorption, platelet adhesion, hemolysis ratio, plasma recalcification time, complement activation and whole blood clotting time tests confirmed that the PES/PES-zwitterionic membrane possessed excellent anticoagulation effect, mainly due to the gathering of zwitterions on membrane surface. Meanwhile, the low surface roughness of membrane also played an important role in hemocompatibility. The mutiphysical-chemical properties of the membrane allow it to function with synergy between permeability and hemocompatibility for further blood purification applications. We expect this methodology for construction of an enhanced and promoted hemocompatibility by chemical design will shed light on the material design. And this facile approach may have great potential in fabrication of blood purification membrane in large scale.

In humid/cold regions, natural wood is vulnerable to mildew, cracking or tremendous strength loss due to their intrinsic hydrophilicity and porous architecture. Herein we report an effective strategy to create omni-surface hydrophobic wood with high flexural strength and excellent frost-resistance. This facile method involves the removal of lignin/hemicellulose, omni-surface hydrophobic treatment and fast hot-pressing densification. Water contact angles of 156 ± 4° and 124 ± 4° were revealed on the outer surface and torn inner surface, respectively. The omni-surface hydrophobicity was achieved by the synergetic effect of steric hindrance of stringed silica nanoparticles and low surface energy of fluorosilylated groups. An easy, fast hot-pressing process offers fourfold increase in flexural strength to 228 MPa. Without hydrophobic treatment, the accelerated freeze-thaw tests cause a cliff drop in flexural strength and cracking for densified wood. In contrast, the omni-surface hydrophobic densified wood shows an excellent frost-resistance and dimensional stability. Such easy, scalable and effective approach holds great potential for developing high-performance, frost-resistant engineering materials in humid/cold regions.

A novel thin film nanocomposite (TFN) forward osmosis (FO) membrane with a positively charged and nano-functional selective layer has been developed for effective heavy metal ions removal. The selective layer is constructed by penetrating the polydopamine modified zeolitic imidazolate framework (ZIF-8@PDA) in the poly(ethyleneimine)/1,3,5-benzenetricarboxylic acid chloride (PEI/TMC) crosslinked matrix. Compared with the pristine thin film composite (TFC) membrane, the thin film nanocomposite membrane (0.05 wt % nanofillers loading) exhibits a higher water flux (20.8 vs12.8 LMH) without losing of selectivity in terms of Js/Jw ratio (0.25 vs 0.20 g L-1) in FO mode. This improvement of the permeability is mainly attributed to the optimized selective layer with good wettability and loose structure. Besides, the modified PDA layer facilitates the affinity between the nanofillers and selective layer, which results in an ideal selectivity. In addition, this modified membrane shows a high heavy metal ion (Cu2+, and Ni2+ and Pb2+) rejection (>96%) in FO mode. Our finding offers a simple and efficient method to enhance the FO performance of membrane by designing the selective layer for treating heavy metal wastewater.

The antifouling properties of a polyvinylidene fluoride (PVDF) membrane were remarkably enhanced by facile incorporation of an amphiphilic triblock copolymer poly(N,N-dimethylamino-2-ethylmethacrylate)-b-polydimethylsiloxane-b-poly(N,N-dimethylamino-2-ethylmethacrylate) (PDMAEMA-b-PDMS-b-PDMAEMA) synthesized via the atom transfer radical polymerization and subsequent surface zwitterionicalization, which provided a stable fouling-resistance interface to avoid undesirable “hydrophobic recovery”. As compared with the pure PVDF membrane, the total flux decline ratio of protein pollution parameters is substantially reduced as low as 14.5% and the BSA rejection of the blend membranes is increased from 33% to 90%, which proves the decrease of effective membrane pore size. The dramatic performance enhancement is attributed to the formation of unique rod-like micelles on the zwitterionic membrane surface due to the self-assembly of the amphiphilic polymer during quaternization. The spontaneous migration of PDMAEMA segments to the membrane surface as conformed by XPS measurement results in significant improvement of the wetting properties, and in situ quaternization further expands the migration rate. The continual migration of the internal amphiphilic copolymers can form a renewable surface to ensure excellent antifouling and durability as conformed by the time-dependent flux test for 30 days. Furthermore, the elastic hydrophobic segments PDMS act as anchors in the matrix, which effectively prevent the elution of amphiphilic polymer. This one-step approach to achieve surface zwitterionicalization is promising to provide a simple strategy for the preparation of multifunctional zwitterionic polymers on the surface of polymeric membrane materials to meet with various demands for further applications, i.e. antifouling and antibacterial properties, etc.

In this work, an antifouling poly(vinylidene fluoride) (PVDF) membrane was fabricated through covalent surface immobilization of a zwitterionic serine-based layer via facile free radical cross-linking polymerization of serine methacrylate (SerMA) on the membrane surface. The unique network structure along with the zwitterionic nature of serine was expected to endow the prepared membranes with excellent wetting and antifouling abilities. Upon modification, wettability of the membranes was improved significantly with the water contact angle decreased to as low as 32°. Protein adsorption on the membrane surface was suppressed remarkably to as low as 4.8 μg cm−2. Filtration experiments further demonstrated that the modified membranes showed higher flux (both water and BSA solution), higher BSA rejection ratio and much better antifouling properties. These results suggest that the zwitterionic serine-based layer on the membrane surface provided an ideal barrier between the membrane substrate and the pollutants.

A series of amphiphilic block copolymers containing hydrophobic polydimethylsiloxane (PDMS) segments and hydrophilic poly(N,N-dimethylacrylamide) (PDMAAm) segments have been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization, which were then crosslinked into well-defined amphiphilic conetworks (APCNs) via ultraviolet (UV) induced thiol–ene click chemistry. Briefly, a PDMS-based RAFT agent was synthesized from the esterification of trithiocarbonate and bis(hydroxyethyloxypropyl) PDMS, and was used to control the RAFT polymerization of monomer DMAAm and allyl methacrylate (AMA) to form amphiphilic copolymers with a well-defined molecular mass and narrow dispersity. The amphiphilic copolymers were then crosslinked via UV induced thiol–ene click chemistry into APCNs, which showed unique amphiphilic characteristics as well as good mechanical properties, making them potential candidates in biomaterials. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) inferred that the resultant APCN exhibited the behavior of microphase separation with a small channel size and uniform phase domain. Therefore, this kind of APCN possessed excellent comprehensive properties, i.e. a well-defined and co-continuous microstructure and high water uptake properties with a homogeneous hydrophilic channel, low cytotoxicity, high mechanical strength (2.1 ± 0.7 MPa) and elongation ratio (173 ± 17%), suggesting a promising biomaterial candidate for contact lenses, drug controlled systems, biomedical scaffolds for tissue engineering and supports for biocatalysts.

This work presented a novel kind of one-dimensional multi-functional modifier for membrane materials. Cysteine modified silver nanowires (C-AgNWs) were used to modify polyvinylidene fluoride (PVDF) membranes and the comprehensive optimized properties including separation efficiency, mechanical strength and antifouling ability of PVDF membranes demonstrated that monodisperse, orientated and zwitterionic C-AgNWs were an efficient modifier for the PVDF ultrafiltration membrane. The objective of this work was to comprehensively improve the application performance of polymer materials using the special hybrid mechanism of one-dimensional nanomaterials.

Antifouling PVDF membranes were fabricated through the covalent binding of lysine methacrylamide (LysAA) brushes on the membrane surface via mussel-inspired surface-initiated atom transfer radical polymerization (SI-ATRP). The zwitterionic pLysAA brushes were immobilized on the membrane surface as well as the inner pore surface, which was conducive to enhance the hydrophilicity and separation properties of PVDF membranes due to the strong hydration capacity of zwitterions and amide groups in the brushes. Upon modification, the wetting and antifouling properties of the graft membranes were improved significantly with the water contact angle reduced to as low as 37° and the water flux recovery ratio increased to as high as 95%. This work provides an effective alternative to the traditional poly(ethylene glycol) or poly(betaine)-based materials for the fabrication of low-fouling membranes, which may find its application in blood purification, protein separation and water treatment.

In this work, acidic ionic liquid glycine hydrochloride (Gly·HCl) is reported as a new solvent for dissolving chitosan. The regenerated chitosan fibers were fabricated by a wet spinning process and characterized by scanning electronic microscopy, fourier transform infrared spectroscopy, wide-angle X-ray diffraction and thermal gravimetric analysis. The result shows that the regenerated chitosan fibers had the same chemical structure as the raw chitosan flake, however, its thermal stability and crystallinity is a little low. Furthermore, a new mechanism of dissolving chitosan in ionic liquid was proposed. The chitosan fibers had soft feeling, excellent antibacterial property and have huge potential application in biomaterials.

A well-defined triblock copolymer poly(methyl methacrylate)-block-poly(ethylene glycol)-block-poly(methyl methacrylate) (PMMA-b-PEG-b-PMMA) synthesized via atom transfer radical polymerization was employed for the antifouling modification of poly(vinylidene fluoride) (PVDF) membrane by facile blending method. Novel terry pile-like structure of amphiphilic copolymer PMMA-b-PEG-b-PMMA was proposed to be formed on membrane surface due to the segregation behavior of the amphiphilic copolymer as verified by X-ray photoelectron spectroscopy analysis. The antifouling properties of the modified membranes were improved remarkably due to the formation of uniform hydrate layer as confirmed by water contact measurement. The permeation results showed that membranes blended with the amphiphilic copolymer exhibited higher water flux (up to 150%), higher BSA solution flux (up to 330%) and higher flux recovery ratio (up to 97%) than pure PVDF membrane, while BSA rejection ratio remained more or less the same. These results provide a promising competency of PVDF composite membrane in waste water treatment and water purification.

A series of amphiphilic conetworks (APCNs) is synthesized through crosslinking of well-defined tri-arm star diblock copolymers via atom transfer radical polymerization. A new three-arm initiator is synthesized to initiate the polymerization of 2-hydroxyethyl methacrylate (HEMA) via “core-first” method. The resulting star HEMA homopolymers with well-defined molecular weight and narrow polydispersity are used as macroinitiator to incorporate allyl methacrylate to get the star diblock copolymers. Then, the precursors with allyl pendant groups are fully crosslinked with polyhydrosiloxanes through hydrosilylation. The so-prepared APCNs exhibit unique properties of microphase separation of hydrophilic (HI) and hydrophobic (HO) phases with small channel size, a variable swelling capacity, excellent biocompatibility, and outstanding mechanical strength (2 ± 0.5 MPa). The properties of APCNs depend on the ratio of HI to HO, which can be regulated via precise synthesis of the star diblock copolymers. The APCNs show well-controlled drug release to choline theophyllinate, suggesting a promising intelligent drug carrier for controlled release. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 2537–2545

A highly hydrophilic PVDF membrane was fabricated through chemically binding TiO2 nanoparticles and a poly(vinyl alcohol) (PVA) layer onto a membrane surface simultaneously. The chemical composition of the modified membrane surface was determined by X-ray photoelectron spectroscopy, and the binding performance of TiO2 nanoparticles and the PVA layer was investigated by a rinsing test. The results indicated that the TiO2 nanoparticles were uniformly and strongly tailored onto the membrane surface, while the PVA layer was firmly attached onto the surface of TiO2 nanoparticles and the membrane by adsorption-cross-linking. The possible mechanisms during the modification process and filtration performance, i.e., water permeability and bovine serum albumin (BSA) rejection, were investigated as well. Furthermore, antifouling property was discussed through multicycles of BSA solution filtration tests, where the flux recovery ratio was significantly increased from 20.0% for pristine PVDF membrane to 80.5% for PVDF...

A type of nano-chitin whisker (NCW) reinforced poly (vinylidene fluoride) (PVDF) membranes were prepared through non-solvent induced phase separation process, which exhibited significant improvement of mechanical properties, water permeability and especially antifouling property. The pure water flux of resulting composite membranes with 52% improvement in mechanical properties reached 392 L m−2 h−1 in comparison to 184 L m−2 h−1 for pure PVDF membrane (without NCW addition), while flux recovery ratio was significantly increased from 13% for pure PVDF membrane to 92% for PVDF/NCW composite membrane because of the perfect entrapment of NCW in PVDF matrix, which resulted in ideal morphology, i.e. decreased surface mean pore size with narrow pore size distribution, increased porosity, hydrophilicity and surface roughness, where the semi-closed pores of pure PVDF membrane are changed to interconnected pore structure of composite membrane. These results were better than those reported in the literature, suggesting a promising competency of PVDF/NCW composite membrane in wastewater treatment and water purification.

In this work, a novel modification method was introduced to improve the antifouling property of polyvinylidene fluoride (PVDF) ultrafiltration membranes, which were prepared with a one-pot process using plasma pretreatment and graft polymerization of PVDF powder. The amphiphilic copolymer of polyvinylidene fluoride-g-polyacrylic acid (PVDF-g-PAA) present in the modified PVDF membrane was demonstrated by infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The improved wetting ability was conducive to improve the water flux, bovine serum albumin rejection and antifouling ability of modified PVDF membranes. A totally novel pH quantitative method was employed to investigate the antifouling property based on the acid–base reaction of the amino acid residues of BSA (pollutant), according to the detected change of BSA adsorption amount on membrane surface and pore surface before and after modification, less irreversible fouling was detected in the modified PVDF membrane due to the existence of PVDF-g-PAA, and it was more convenient to remove the pollutants in the pores of modified PVDF membranes by water flushing.

Branched polyethylene glycol (PEG) was anchored onto a membrane surface by efficient covalent self-assembly to optimize the separation and antifouling properties of polyvinylidene fluoride (PVDF) ultrafiltration membranes based on its excellent hydrophilic and antifouling properties. The results showed that the surface self-assembly method could effectively improve the stability of PEG and the surface wetting ability of the PVDF membrane, and simultaneously enhanced the water flux and rejection of modified membranes. Meanwhile, the fouling results showed the anchored PEG segments on the separation interface contributed to improve the antifouling performance of the PVDF ultrafiltration membrane with significantly improved anti-adsorption capacity for bovine serum albumin (BSA) and expectant water flux recovery ratios for BSA and humic acid (HA), two typical pollutants. This paper provides a sample modification idea and demonstrated covalent self-assembly was an effective method for surface modification.

The polyelectrolyte complex (PEC) layer fabricated by chitosan and sodium alginate was anchored on a membrane surface though plasma treatment and layer by layer self-assembly to improve the antifouling properties of the PVDF membrane. The interface properties of modified PVDF membranes were investigated and the results indicated the presence of the PEC layer was conducive to enhance the hydrophilicity and screening ability of the PVDF ultrafiltration membrane due to the hydrophilic crosslinking structure. Furthermore, the fouling resistance including anti-adsorption ability and dynamic antifouling ability for pollutant filtration of modified PVDF membranes were significantly improved due to the anchored PEC layer. For the CS–SA-3 membrane with an assembly number of 3, the adsorption mass of BSA on the membrane surface was only 4 μg cm−2 and the FRR-W values increased to 89%, 99% and 98% for the three typical pollutants of bovine serum albumin, sodium alginate and humic acid, respectively. It was demonstrated that the PEC layer could be used as an antifouling material to improve the antifouling ability of hydrophobic membranes though decreasing the reversible fouling. This article also aimed to provide a simple method to fabricate the antifouling interface.

The morphological and structural properties of plasticized spinning polyacrylonitrile (PAN) fibers during the stabilization process were investigated. The PAN fibers were subjected to stabilization treatment following a three-stage heating process. The PAN fibers were characterized by elemental analysis, Fourier transform infrared spectroscopy and X-ray diffraction; it was found that the stabilization degree of the PAN fibers is significantly higher than that of commercial PAN fibers. For plasticized spinning fibers, stabilization can occur in the crystalline region even at a low temperature of 180 °C; oxygen containing groups in the crystalline region generated during the plasticized spinning process may be responsible for this phenomenon. At a stabilization temperature of 230 °C, the cross-section of plasticized spinning fibers exhibits a large block stacking structure with obvious grooves among them, whereas a cross-section of the fibers shows a sheet-like divergence structure at 260 °C. The mechanical properties and density test results further indicate that 260 °C is a critical stabilization temperature for plasticized spinning fibers. Moreover, it is observed that a slight skin-core structure can be formed during the stabilization process.

The plasticized spinning and cyclization behaviors of polyacrylonitrile (PAN) and polyacrylonitrile/functionalized carbon nanotube (PAN/CNT-COOH) composite fibers were studied. The PAN/CNT-COOH fibers containing 0.8 wt% CNTs exhibit excellent tensile strength and modulus, i.e. 0.475 GPa and 10.93 GPa, which are 69.6% and 40.13% improvement respectively, compared to their precursor fibers. The changing trend of crystallinity of PAN/CNT-COOH fibers is associated with the heat exchange rate and oriented-crystallization rate, which can be confirmed by the X-ray diffraction (XRD) results. The cyclization behaviors of the fibers were examined using X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The results show that cyclization of PAN/CNT-COOH fibers is initiated by three types of initiating agents, i.e., modified CNTs (CNTs-COOH), oxygen containing groups generated during the plasticized spinning and comonomers. Meanwhile, the PAN/CNT-COOH fibers exhibit various cyclization behaviors induced by high spinning speeds.

Hybrid polyvinylidene fluoride (PVDF) ultrafiltration (UF) membranes with excellent antifouling properties were prepared by non-solvent-induced phase separation through blending zwitterionic SiO2 nanoparticles. Lysine was used to modify SiO2 nanoparticles to generate a surface zwitterion of the amino acid type. Zwitterionic SiO2 nanoparticles were distributed uniformly in the membrane bulk to avoid massive agglomeration and to significantly improve the hydrophilicity and separation performance of PVDF UF membranes. The amount of BSA adsorbed on a hybrid ZP-5% membrane surface of static fouling test decreased to 10 μg cm−2, and the secondary water flux recovery rate (FRR) increased to more than 95% for the dynamic antifouling test of BSA and HA. The addition of zwitterionic SiO2 nanoparticles enhanced the antifouling ability of the membrane through inhibiting irreversible fouling and prolonging the service life of the PVDF UF membrane.

Polydimethylsiloxane-graft-polyethylene glycol (PDMS-graft-PEG), an amphiphilic polymer with four hydrophilic arms, was prepared and used to improve the antifouling property of PVDF membranes by a dip-coating method. The interface properties of the modified PVDF membranes were investigated and it was found that the increased molecular weight of the PEG segment exhibited a negative effect on the anchoring ability of the PDMS-graft-PEG on the membrane surface. However, the antifouling properties of the modified membranes were significantly improved due to the dual-mode antifouling ability of fouling repulsion (PEG) and fouling release (PDMS). The adsorption mass of BSA on the modified membrane surface decreased to a low level, and an enhanced water flux recovery ratio after washing (FRR-W) of the modified membranes was obtained for two typical pollutants of bovine serum albumin and sodium alginate. It was demonstrated that surface anchoring is an effective way to improve the interface characteristics of membrane materials with functional polymers.

Novel photocurable ternary polymer networks were prepared by incorporating N-(4-hydroxy-3-methoxybenzyl)-acrylamide (HMBA) into a cross-linked thiol–ene network based on poly(ethylene glycol)diacrylate (PEGDA) and (mercaptopropyl)methylsiloxane homopolymers (MSHP). The ternary network materials displayed bactericidal activity against Escherichia coli and Staphylococcus aureus and reduced the attachment of marine organism Phaeodactylum tricornutum. Extensive soaking of the polymer networks in aqueous solution indicated that no active antibacterial component leached out of the materials, and thus the ternary thiol–ene coating killed the bacteria by surface contact. The surface structures of the polymer networks with varied content ratios were studied by sum frequency generation (SFG) vibrational spectroscopy. The results demonstrated that the PDMS Si-CH3 groups and mimic-capsaicine groups are predominantly present at the polymer–air interface of the coatings. Surface reorganization was apparent after polyme...

The functionalizing nanoporous polyacrylonitrile-based oxidized membrane (PAN–OM) firmly immobilized with highly reactive nanoscale zero-valent iron (NZVI) are successfully prepared via an innovative in situ synthesis method. Due to the formation of ladder structure, the PAN–OM present excellent thermal and chemical stabilities as a new carrier for the in-situ growth of NZVI via firm chelation and reduction action, respectively, which prevent the aggregation and release of NZVI. The developed NZVI-immobilized membrane present effective decolorizing efficiency to both anionic methyl blue and cationic methylene blue with a pseudo-first-order decay and degrading efficiency to trichloroethylene (TCE). The regeneration and stability results show that NZVI-immobilized membrane system can be regenerated without obvious performance reduction, which remain the reactivity after half a year storage period. These results suggest that PAN-based oxidized membrane immobilized with NZVI exhibit significant potential for environmental applications.

The external plasticization of polyacrylonitrile (PAN) with high molecular weight was achieved, where 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was explored as a novel plasticizer. The interaction and plasticization mechanism in PAN/[Bmim]Cl system were investigated. The Fourier transform infrared spectroscopy (FTIR) results show that there exists strong hydrogen interaction between nitrile (C N) groups of PAN and unsaturated C–H of imidazolium rings in [Bmim]Cl at high temperature. The addition of [Bmim]Cl leads to the decrease in glass transition temperature, melting temperature and paracrystalline content of the system due to the high penetration efficiency of [Bmim]Cl. The rheology of the system was studied as well, which proves the occurrence of the cyclization and oxidation reactions of PAN macromolecular chains along with X-ray photoelectron spectrometer and FTIR results. The cyclization reaction is significantly influenced by the [Bmim]Cl content in whole system, which further affects the spinnability of PAN/[Bmim]Cl system and ladder structure of the prepared fibers.

Novel amphiphilic conetworks (APCNs) with uniform channel size were synthesized through end-cross-linking of well-defined amphiphilic triblock copolymers via atom transfer radical polymerization (ATRP). A new ditelechelic polydimethylsiloxane macroinitiator was synthesized to initiate the polymerization of N,N-dimethylacrylamide. The resulting triblock copolymers show well-defined molecular weight with narrow polydisperisty, which are telechelic modified by allylamine and fully cross-linked with polyhydrosiloxanes through hydrosilylation. Transmission electron microscopy shows that the APCN has the behavior of microphase separation with small channel size and uniform phase domain. The resulting APCNs with idealized microstructure exhibit a combination of excellent properties, i.e., superhigh mechanical strength (4 ± 1 MPa) and elongation ratio (175 ± 25%), outstanding oxygen permeability (350 ± 150 barrers), a high water uptake property, and excellent biocompatibility, indicating that in this way, "near perfect" networks are obtained. These results are better than those reported in the literature, suggesting a promising semipermeable barrier for islet encapsulation in relative biomaterial fields.

PVDF/SiO2 hybrid membranes with outstanding antifouling property were prepared from PVDF/glycerol triacetate system via thermally induced phase separation method, and characterized by scanning electron microscope, energy dispersive X-ray spectrometer analyses, differential scanning calorimeter, and wide angle X-ray diffraction. Their properties such as permeability, porosity, pore size distribution, and mechanical performance were also determined. The results show that SiO2 nanoparticles modified by 3-aminopropyltriethoxysilane can be uniformly dispersed in membranes due to improved compatibility between PVDF solution and nanoparticles. The addition of SiO2 particles to PVDF/glycerol triacetate mixture has a strong effect on crystallinity of the resulting hybrid membrane, which does not affect the type of PVDF crystal structure. Water flux recovery ratio is significantly increased from 11.7 % for pure PVDF membrane to 93.8 % for PVDF/SiO2 hybrid membrane with addition of 8 wt% modified SiO2. This remarkable promotion is related to the implantation of SiO2 nanoparticles into the inner surface of membrane, which effectively restrains the adsorption of bovine serum albumin on the pore walls and improves antifouling property of the final membranes. Additionally, pure water flux of the hybrid membrane is increased by 276 %, i.e., from 85 to 320 L m−2 h−1, tensile strength is increased by 26.5 %, and elongation at break is increased by 85.4 % compared with that of pure membrane.

Chitosan membrane possesses huge potential application in many fields, such as biomedicine, wastewater purification and environmental protection, however, the poor mechanical property restricts its further development. In this study, chitin whisker was prepared by hydrolysis method, and was firstly used as an interlayer to fabricate the multilayered chitosan membrane through layer-by-layer method, which is inspired by the natural materials' hierarchical structure. From the results of mechanical testing, it is shown that tensile strength of the multilayered chitosan membranes reaches up to 122.8 MPa, which is about 2.5 times than that of neat chitosan membrane (i.e. 49.5 MPa), and the elongation at break is sharply increased as well.

We propose an interfacial design strategy to prepare novel, highly structure-stable thin film nanocomposite (TFN) nanofiltration (NF) membranes. It employs NMG-assisted dopamine modification on nanoparticles and a substrate, followed by interfacial polymerization. Our approach overcomes two problems that are typical of composite membranes – a weak interlayer interactive force, and poor compatibility between inorganic nanoparticles and a polymer matrix in nanocomposite membranes. The TFN membrane presented here has a high methanol permeance (2.18 L·m−2 ·h−1·bar−1) and a high rejection (99.1%) to acid red 18 (MW = 509 g·mol−1), which is superior to commercial solvent resistant NF (SRNF) membranes and most literature on SRNF membranes. More importantly, our TFN membranes exhibit a high degree of structural stability, demonstrated by immersion in three organic solvents for 15 days and a two day continuous filtration test. Our strategy is facile and highly flexible, has high potential for deployment in SRNF, and may stimulate the development of practical SRNF applications in the near future.