Sulfobetaine Copolymer Research Articles

Zwitterionic Surface Modification of Aldehydated Sulfobetaine Copolymers for the Formation of Bioinert Interfaces

This research successfully developed a zwitterionic copolymer, poly(2-oxoethyl methacrylate-co-sulfobetaine methacrylate) poly(OxMA-co-SBMA), in which the OxMA segments have an aldehyde functional group that can undergo a nucleophilic addition reaction with an amine group to generate a Schiff base. At the same time, SBMA units are employed as antifouling groups. This copolymer is grafted via a graft-to process to the surface of an amine-based substrate to form chemical bonds by dip-coating technology and achieves antifouling properties. The synthesized monomer and copolymers are characterized by Fourier transform infrared (FTIR) spectroscopy and NMR to confirm their chemical structure. Notably, dip-coating technology uses a simple “graft-to” immersion process to achieve nonfouling and antiprotein properties. Compared to the previously reported ″graft-from″ technology, dip-coating has the advantage of a fast and simple procedure and is easy to scale up. The poly(OxMA-co-SBMA) copolymer was grafted onto the amino substrate surface by controlling the dip-coating conditions of different grafting temperatures, grafting time, concentrations of copolymer solution, and copolymer molar ratios. The prepared poly(OxMA-co-SBMA) with an optimum pOxMA/pSBMA molar ratio of 1:4 and a molecular weight of 46.8 kDa exhibited an improvement of hydrophilicity and the best resistance to protein adsorption with over 90% reduction, as well as blood cell activation, tissue cell adhesion, and bacterial attachment on the zwitterionic copolymer-grafted surfaces. The results showed that the modified samples under the best grafting conditions could effectively reduce the biofouling of biomolecules. Meanwhile, it performed well in modified amine-based plastic materials, such as polyurethane tubes and polyamide bending fabrics, which are expected to have broader bioinert application potential in biomedical materials.

Surface Zwitterionization via Grafting of Epoxylated Sulfobetaine Copolymers onto PVDF Membranes for Improved Permeability and Biofouling Mitigation

Grafting of zwitterionic moieties has been shown to overcome the decrease in permeability after membrane modification. Herein, we report the grafting of epoxylated sulfobetaine (poly(glycidyl methacrylate-co-sulfobetaine methacrylate or poly(GMA-co-SBMA)) zwitterionic copolymers onto polyvinylidene fluoride (PVDF) surfaces to obtain superhydrophilic and superoleophobic membranes. The three-dimensionally modified membranes simultaneously exhibit excellent fouling resistance and hemocompatibility with improved water permeability during protein filtration. The zwitterionic moiety in the bulk membrane promotes the formation of a hydration layer, resulting in a dramatic reduction in hydrophobic interactions between the membrane and proteins or bacteria. Zwitterionic polymers establish a relatively electrically neutral surface through the presence of positive and negative charge groups on their pendant, leading to a reduction of adhesion between charged protein molecules and membranes. The modified PVDF surface exhibits very high hemocompatibility for human erythrocytes, platelets, and leukocytes. In the static fouling test, this biofouling hardly adhered to the membrane surface. The developed membrane has 3 times higher water permeability than the unmodified commercial membrane. It also showed a significant improvement in antifouling performance during dynamic fouling testing. Furthermore, flux regeneration of the modified membranes is easier to achieve by simple water recirculation compared to pristine PVDF membranes. Therefore, this study provides a promising way to develop antifouling membrane surface modification, which can be potentially used for bioseparation applications.

Study the Effects of Supramolecular Interaction on Diffusion Kinetics in Hybrid Hydrogels of Zwitterionic Polymers and CNTs

AbstractHybrid hydrogel systems of functionalized multi‐walled carbon nanotubes and zwitterionic sulfobetaine copolymer of thermo‐responsible poly(N‐isopropylacrylamide) (PNIPAM) are synthesized and testified against different existing diffusion kinetic models in neutral, acidic, and basic environments. Evaluating these hybrid hydrogels’ swelling patterns at different pH indicates that changing pH can tailor the diffusion mechanism without affecting its diffusion kinetics. Interestingly, it is also revealed that diffusion kinetics and diffusion mechanisms are two distinct phenomena and can be viewed separately for supramolecular hybrid hydrogel systems. Elovich kinetic model best describes the swelling kinetics of only PNIPAM hydrogel. Diffusion kinetics of hybrid hydrogel of PNIPAM and CNTs or PNIPAM, zwitterion, and CNTs follow pseudo‐first‐order, while pseudo‐second‐order‐kinetics best describe hydrogels with only zwitterions. Evaluation of diffusion mechanism at different pH reveals that hydrogels with only zwitterions follow anomalous non‐Fickian diffusion, whereas only CNTs follow normal Fickian diffusion irrespective of pH; combining both systems leads to a dual‐stage diffusion mechanism at pH 2, which in turn reduces as the pH increases. These observations suggest that synergistic effects of supramolecular interactions can provide a novel property profile to hybrid hydrogels, requiring attention while designing such a system where diffusion is a decisive parameter.

Molecular‐Level Interactions of Nanodisc‐Forming Copolymers Dissected by EPR Spectroscopy

AbstractThis study focuses on analyzing the noncovalent interaction patterns between three lipid‐nanodisc‐forming polymers and nitroxide radicals which are used as small organic tracer molecules. Besides the negatively charged polymers diisobutylene/maleic acid (DIBMA) and styrene/maleic acid (SMA) (2:1), the solvation behavior of a newly synthesized zwitterionic styrene/maleic amide sulfobetaine copolymer named SMA‐sulfobetaine (SB) is characterized. The applied spin probes vary in their respective chemical structure, allowing the report of different local micropolarities and nanoscopic regions by recording temperature‐dependent continuous‐wave electron paramagnetic resonance (CW EPR) spectra. In combination with light scattering experiments, a nanoscopic interpretation of the dominant polymer/guest molecule interaction patterns is provided. The results indicate that in SMA and DIBMA, ionic interactions dominate the interaction patterns with other molecules. In SMA‐SB, the zwitterionic side chains mainly induce a dynamic assembly with guest molecules due to weaker noncovalent interactions. Depending on the applied spin probe, temperature‐dependent CW EPR measurements reveal nanoscopic cloud points depending on the interaction patterns with SMA‐SB which can occur more than 20 °C below its macroscopically observed upper critical solution temperature. Finally, the detailed dissection of interaction patterns may provide a better understanding that may even allow tuning the polymers’ properties for use in lipid nanodisc formation.

Effective Permeation of Anticancer Drugs into Glioblastoma Spheroids via Conjugation with a Sulfobetaine Copolymer.

Three-dimensional cell aggregates (spheroids) are becoming a research focus because their construction is similar to that in vivo microenvironments, enabling the acceleration of drug discovery and reducing the need for animal tests, and other advantages. However, the delivery of drugs to the inside of spheroids is time-consuming and has low efficiency. In this study, we selected a sulfobetaine copolymer that translocates to the cell membrane in monolayer cultured cells as a nanocarrier of anticancer drugs. Doxorubicin (Dox) and 17-demethoxy-17-allylamino geldanamycin (17AAG) were modified to the copolymer of sulfobetaine methacrylate and poly(ethylene glycol) methacrylate, P(SB-PEG), and added to glioblastoma A-172 cell spheroids. Dox-P(SB-PEG) showed fast permeation into A-172 spheroids, and the fluorescence in cells was observed in the center area of the spheroids within 1 h of polymer addition. Conversely, only the outer one to two cell layers of spheroids were observed when Dox was added to the spheroids. Dox-P(SB-PEG) in A-172 spheroids was localized in the mitochondria of each cell and exhibited comparable drug efficacy to that of Dox in growth inhibition assays of A-172 spheroids. Moreover, approximately 10-fold higher drug efficacy in growth inhibition and invasion of A-172 spheroids was found using 17AAG-P(SB-PEG). Conjugating anticancer drugs with P(SB-PEG) is a promising strategy to enhance drug permeation and efficacy against spheroid cells.

Improved antibiofouling properties of photobioreactor with amphiphilic sulfobetaine copolymer coatings

Biofouling is a critical challenge for the commercial application of photobioreactors for microalgae cultivation. In this work, a series of amphiphilic sulfobetaine copolymers (ASC) with different ratios of sulfobetaine (SBMA) and 2, 2, 2-trifluoroethyl methacrylate (TFMA) were synthesized via a monomer-starved seeded semi-continous emulsion polymerization method and were used to improve the antibiofouling capability of ethylene-vinyl acetate copolymer (EVA) film by surface coating method. Effects of the SBMA/TFMA ratio on the resultant ASC latexes and coating properties were investigated. With the increase of the SBMA/TFMA ratio, the particle diameter, polydispersity index and water uptake of ASC latexes and coating decreased from 261.8 nm to 144.9 nm, 0.198 to 0.054 and 26.28 % to 7.84 %, respectively, and increased afterwards. Fourier transform Infrared (FT-IR) spectra and X-ray photoelectron spectroscopy analysis (XPS) indicated that SBMA and TFMA were introduced onto the EVA film surface successfully. The contact angle of ASC modified EVA (EVA-ASC) film sharply decreased after immersed in water. The EVA-ASC film either in dry, or in water swollen state exhibited excellent optical transparency in the visible light. The adsorption of bovine serum albumin and Chlorella sp. on the EVA-ASC surface was investigated with protein and microalgae adsorption assay. It was shown that the EVA-ASC film had excellent protein and microalgae absorption resisting characteristic, the density of absorbed protein and microalgae decreased 92 % and 50 % compared with those of EVA film, respectively.

Solution behavior of water‐soluble poly(acrylamide‐co‐sulfobetaine) with intensive antisalt performance as an enhanced oil‐recovery chemical

ABSTRACTIn the process of oilfield development, salt tolerance is an important property for enhanced oil‐recovery (EOR) chemicals. In this study, we synthesized two acrylamide‐based sulfobetaine copolymers containing 2‐hydroxy‐3‐[(3‐methacrylamidopropyl)dimethylammonio]propane sulfonate (SHPP) or 3‐(4‐acry‐loyl‐1‐methyl‐piperazinio)‐2‐hydroxypropane sulfonate (SHMP). The interactions between these two copolymers and inorganic salts were compared, and the apparent viscosity (ηapp) behaviors of copolymer–salt solutions at different shear rates and temperatures were investigated. We found that the ηapp of PAPP and PAMP showed intensive antisalt performance, exhibiting an excellent antipolyelectrolyte effect. The ηapp retention value of 30,000 mg/L PAMP in brine was 86.47 mPa s at 510 s−1, and when the temperature was increased to 90 °C, it was 99.73 mPa s; this was better than that of PAPP under the same conditions. Therefore, PAMP was more applicable as an EOR chemical that have outstanding salt tolerance and temperature resistance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46235

Antibacterial activity, thermal stability and ab initio study of copolymer containing sulfobetaine and carboxybetaine groups

Here, we have explored the antibacterial activity, thermal stability and theoretical study of two copolymers that contain sulfobetaine and carboetaine moiety. Copolymers were synthesized based on Schiff base chemistry with generation of zwitterionic centres by nucleophilic addition of sultone/lactone. To predict and confirm the molecular structure of zwitterionic polyelectrolyte molecule, the theoretical study of structural features and other thermodynamic characteristics of copolymer constituents was obtained by ab initio calculations. Various parameters such as geometry optimization, energy calculations, frequency calculations and intrinsic reaction coefficient (IRC) are simulated using Hartree Fock (HF) method. The geometry optimizations are analyzed at HF/3-21 G default level of theory. The vibrational frequency is calculated via density functional theory (DFT)/B3LYP 6-31G*(d) level whose values are in accord with the experimental observed frequency. Both copolymers have been successfully assessed for antibacterial activity against Staphylococcus aureus and Pseudomonas aeuroginosa bacterial strains by disc diffusion method. The antibacterial study helped in evaluating zone of inhibition, minimum inhibitory concentration and minimum bactericidal concentration. Sulfobetaine copolymer is found to be more effective in curtailing the infection caused by bacteria as compared to carbobetaine.

Zwitterionic surface grafting of epoxylated sulfobetaine copolymers for the development of stealth biomaterial interfaces

Most biomaterials have a lack of a simple, efficient and robust antifouling modification approach that limits their potential for biomedical applications. The challenge is to develop a universal surface grafting solution to meet the antifouling requirement. In this work, a new formulation of zwitterionic sulfobetaine-based copolymer, ploy(glycidyl methacrylate-co-sulfobetaine methacrylate) (poly(GMA-co-SBMA)), is designed as a chemical for grafting onto material and is introduced for the surface zwitterionization of versatile biomaterials, including ceramic, metal, and plastics. The grafting principle used to stabilize the poly(GMA-co-SBMA) on the target surfaces is based the base-induced ring opening reaction between epoxied and hydroxyl groups. A universal surface modification procedure was developed and performed from an optimized sequence of ultra-violet ozone pretreatment and trimethylamine-catalyzed zwitterionization on a selective case of versatile surfaces including silicon wafer, ceramic glass, titanium, steel, and polystyrene. The prepared poly(GMA-co-SBMA) with an optimum PGMA/PSBMA ratio of 0.23 and a molecular weight of 25kDa exhibited the best resistance to fibrinogen adsorption with over 90% reduction as well as blood cell activation, tissue cell adhesion and bacterial attachment on the zwitterionic copolymer grafted surfaces. The developed antifouling grafting introduces a universal modification method to generate zwitterionic interfaces on versatile biomaterial substrates, providing great potential for application in medical device coating. Statement of SignificanceA simple, efficient and robust antifouling modification approach is critical for many scientific interests and industrial applications. In current stage, the existing available zwitterionic modifications suffer from the lack of universal surface grafting solution to achieve the antifouling requirement on versatile biomaterial substrates. In this study, we synthesized and characterized a new zwitterionic sulfobetaine-based copolymer, ploy(glycidyl methacrylate-co-sulfobetaine methacrylate) (poly(GMA-co-SBMA)), which is designed as chemical grafting onto material and introduced for the surface zwitterionization of versatile biomaterials, including ceramic, metal, and plastics. This research have a promising opportunity for the application of stealth biomaterial interfaces on the next generation of medical devices.

Changes in the Properties and Self‐Healing Behaviors of Zwitterionic Nanocomposite Gels Across Their UCST Transition

SummaryCharacteristic properties of zwitterionic nanocomposite (NC) gels consisting of a sulfobetaine copolymer and inorganic clay were investigated. The zwitterionic NC gels were synthesized with different ratios of monomer (x) and clay content (n) by the in situ free‐radical polymerization of two monomers, a sulfobetaine monomer (A3) and acrylamide derivative (D), in the presence of exfoliated clay in aqueous media. The resulting zwitterionic A3Dx‐NCn gels were all structurally uniform and mechanically tough because of the polymer–clay network. A3Dx‐NCn gels exhibited a thermoresponsive phase transition with an upper critical solution temperature (UCST) for x ≤ 10 and n ≤ 5. The changes in the property of the A3D10‐NC3 gel across the UCST transition were elucidated in terms of optical transmittance, gel volume, dynamic viscoelasticity, and tensile mechanical properties, in addition to the change in self‐healing behavior.

Hydrophobically Modified Sulfobetaine Copolymers with Tunable Aqueous UCST through Postpolymerization Modification of Poly(pentafluorophenyl acrylate)

Polysulfobetaines, polymers carrying highly polar zwitterionic side chains, present a promising research field by virtue of their antifouling properties, hemocompatibility, and stimulus-responsive behavior. However, limited synthetic approaches exist to produce sulfobetaine copolymers comprising hydrophobic components. Postpolymerization modification of an activated ester precursor, poly(pentafluorophenyl acrylate), employing a zwitterionic amine, 3-((3-aminopropyl)dimethylammonio)propane-1-sulfonate, ADPS, is presented as a novel, one-step synthetic concept toward sulfobetaine (co)polymers. Modifications were performed in homogeneous solution using propylene carbonate as solvent with mixtures of ADPS and pentylamine, benzylamine, and dodecylamine producing a series of well-defined statistical acrylamido sulfobetaine copolymers containing hydrophobic pentyl, benzyl, or dodecylacrylamide comonomers with well-controllable molar composition as evidenced by NMR and FT-IR spectroscopy and size exclusion chromatography. This synthetic strategy was exploited to investigate, for the first time, the influence of hydrophobic modification on the upper critical solution temperature (UCST) of sulfobetaine copolymers in aqueous solution. Surprisingly, incorporation of pentyl groups was found to increase solubility over a wide composition range, whereas benzyl groups decreased solubility—an effect attributed to different entropic and enthalpic contributions of both functional groups. While UCST transitions of polysulfobetaines are typically limited to higher molar mass samples, incorporation of 0–65 mol % of benzyl groups into copolymers with molar masses of 25.5–34.5 kg/mol enabled sharp, reversible transitions from 6 to 82 °C in solutions containing up to 76 mM NaCl, as observed by optical transmittance and dynamic light scattering. Both synthesis and systematic UCST increase of sulfobetaine copolymers presented here are expected to expand the scope and applicability of these smart materials.

Effects of Polymer Concentration on Structure and Properties of Zwitterionic Nanocomposite Gels

Zwitterionic nanocomposite gels (Zw‐NC gels) composed of a zwitterionic sulfobetaine copolymer and inorganic clay (hectorite) are synthesized through the in situ free‐radical copolymerization of N,N‐dimethyl(acrylamidopropyl)ammonium propanesulfonate (90 mol%) and N,N‐dimethylacrylamide (10 mol%) with exfoliated clay platelets in an aqueous medium. The effects of polymer concentration (Cp) on the dynamic viscoelasticity, tensile mechanical properties, transparency, and the thermosensitivity with the upper critical solution temperature (UCST) of the Zw‐NC gels are investigated in the range Cp = 26–260 g L−1 and are compared with those of chemically cross‐linked zwitterionic gels. All the mechanical and thermosensitive properties strongly change depending on the type of network and Cp. The Cp‐induced changes in the polymer‐clay structure of the Zw‐NC gel are discussed based on the mechanical, optical, and thermosensitive properties, and on transmission electron microscopy and X‐ray diffraction measurements. image

Biocompatible Zwitterionic Sulfobetaine Copolymer‐Coated Mesoporous Silica Nanoparticles for Temperature‐Responsive Drug Release

A novel nanocontainer, which could regulate the release of payloads, has been successfully fabricated by attaching zwitterionic sulfobetaine copolymer onto the mesoporous silica nanoparticles (MSNs). RAFT polymerization is employed to prepare the hybrid poly(2-(dimethylamino)ethyl methacrylate)-coated MSNs (MSN-PDMAEMA). Subsequently, the tertiary amine groups in PDMAEMA are quaternized with 1,3-propanesultone to get poly(DMAEMA-co-3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate)-coated MSNs [MSN-Poly(DMAEMA-co-DMAPS)]. The zwitterionic PDMAPS component endows the nanocarrier with biocompatibility, and the PDMAEMA component makes the copolymer shell temperature-responsive. Controlled release of loaded rhodamine B has been achieved in the saline solutions.

Surface Photografting of Novel Sulfobetaine Copolymers on Silica

A couple of novel sulfobetaine copolymer is developed via Michael-type addition reaction. The comonomers, diamines and maleimide react via Michael reaction through UV irradiation using AIBN as photoinitiator producing polyamine chain. Further, sulfobetaine copolymers were obtained on treatment of the polyamine with sulfopropylating agent, 1,3-propane sultone. These novel sulfobetaine polymers were grafted on silica surface to produce responsive biocompatible surface. This easy straightforward, catalyst free facile protocol for synthesis of polymer grafted surface is useful for developing biomedical devices. Additionally, both the copolymers show fluorescence characteristics.

Synthesis, Characterization and Photoluminescence Study of Novel Sulfobetaine Polyelectrolytes

A novel sulfobetaine copolymer is developed via polycondensation approach. The comonomers, melamine, condenses with a diketone, 5,5-dimethyl-1,3-cyclohexane (dimedone) to produce polyimine chain based on Schiff base chemistry. Dimedone-[N,N' melaminium] propane sulfonate copolymer crystals were obtained on treatment of the polyimine with sulfopropylating agent, 1,3-propane sultone with a crosslinker, di(ethylene glycol diacrylate) (DEGDA). This crosslinked sulfobetaine polymer yielded fine needle like single crystals and shows strong blue fluorescence and a week green phosphorescence. Multi-exponential fluorescence decay function indicates the presence of different conformers both in solution and crystalline phase. This easy straightforward protocol for synthesis of crystalline, soluble, and luminescent polymer could prove to be a landmark in development of next generation smart functional materials.

Photo-reversible and selective Cu2+ complexation of a spiropyran-carrying sulfobetaine copolymer in saline solution

A sulfobetaine copolymer (1) carrying a photochromic spiropyran residue was synthesized, which reversibly isomerized between the closed and open forms in pure water and in saline by irradiation with visible light. The thermodynamic stability of the open form of the spiropyran methacrylate (SPMA) units of compound 1 was reduced upon increasing NaCl concentration. In addition, photo-reversible and selective Cu2+ complexation in saline solution ([NaCl] = 1.0 wt%) was achieved using compound 1 with metal ions (Cu2+, Zn2+, Ni2+, or Co2+). Covalently cross-linked compound 1 showed selective Cu2+ adsorption in pure water. In contrast, the other metal ions were increasingly adsorbed as NaCl concentration increased, resulting in lower selectivity of Cu2+ ion adsorption with 1, e.g., the ratios of adsorption of Cu2+, Zn2+, Ni2+, and Co2+ with 1 in 10 wt% saline were 73, 20, 10, and 3%, respectively, while only Cu2+ adsorption was observed in a solution of 1.0 wt% NaCl. Because the stability of the open form of the SPMA units and the metal complexation of 1 were influenced by NaCl concentration, the electrostatically cross-linked networks of the zwitterionic sulfobetaine units of 1 may be loosened by NaCl addition, resulting in easy entry of metal ions into the network. The order of metal complexation among the four metals corresponded to the Irving–Williams series. Hydrogen-bonded networks of water molecules also may contribute to the relatively ineffective selective adsorption of Cu2+ ions by 1 compared to the electrically neutral spiropyran-carrying copolymer of N-isopropylacrylamide, 2.

A study of aggregation behavior of a sulfobetaine copolymer in dilute solution

A copolymer poly(acrylamide-co-3-[N-(2-methacroyloylethyl)-N, N-dimethylammonio]-propane sulfonate) (P(AM/DMAPS)) was synthesized via conventional free-radical polymerization in aqueous media. Its aggregation and disaggregation in aqueous solution were studied as a function of copolymer concentration, ionic strength and ageing time at different temperature by gel permeation chromatography combined with laser light scattering (GPC-MALLS) technique, static and dynamic laser light scattering. GPC-MALLS analysis shows that at low copolymer concentrations (below 0.4 g.L−1), a decrease of both apparent weight-average molecular weight and radius of gyration is observed due to the dissociation of the interchain association. With increasing copolymer concentration, the interchain association is enhanced and both apparent weight-average molecular weight and radius of gyration increase. Correspondingly, the exponent ρ of the radius of gyration/molecular weight (Rg−Mw) relationship shows an increase from 0.29 to 0.6 with increasing copolymer concentration (below 0.4 g.L−1), and then decreases continuously to 0.33 with further increasing copolymer concentration. Dynamic laser light scattering studies reveal that the addition of a small amount of salts (below 0.1 mol.L−1) leads to the disaggregation of the intra- and interchain aggregation. Further addition of salts results in the enhancement of interchain aggregation. The influence of various anions on the aggregation behavior increases in the order Cl − < Br − < I −. The prolonging of the ageing time at 25 °C and 70 °C leads to the disaggregation of the interchain association of P(AM/DMAPS) copolymer in both deionzied water and 0.15 mol.L−1 NaCl solution.

Electrospinning zwitterion-containing nanoscale acrylic fibers

Abstract Free radical copolymerization of n -butyl acrylate and a sulfobetaine methacrylamide derivative provided high molecular weight zwitterionic copolymers containing 6–13 mol% betaine functionality, and the electrospinning of low T g zwitterionomers was explored for the first time. Copolymerizations were performed in dimethylsulfoxide (DMSO) rather than fluorinated solvents previously reported in the literature. Dynamic mechanical analysis of zwitterionomer films revealed biphasic morphology and featured a rubbery plateau and two distinct thermal transitions. Electrospinning from chloroform/ethanol (80/20 v/v) solutions at low concentrations between 2 and 7 wt% afforded nanoscale polymeric fibers with diameters near 100 nm. The presence of only 6 mol% zwitterion allowed the formation of low T g , free-standing, non-woven mats, and we hypothesize that zwitterionic aggregation rather than chain entanglements facilitated electrospinning at these relatively low solution concentrations. To our knowledge, this is the first report of electrospun zwitterionic polymers and these non-woven membranes are expected to lead to new applications for sulfobetaine copolymers.

Improved antifouling property of zwitterionic ultrafiltration membrane composed of acrylonitrile and sulfobetaine copolymer

A random copolymer poly((2-dimethylamino ethyl methacrylate)-acrylonitrile) (PAN–DMAEMA) was synthesized by copolymerization of 2-dimethylamino ethyl methacrylate with acrylonitrile through the water phase suspension polymerization method. The PAN–DMAEMA copolymer was then reacted with 1,3-propane sultone (PS) to convert the DMAEMA group into zwitterionic N, N-dimethyl- N-methacryloxyethyl- N-(3-sulfopropyl) (DMMSA) functional group. The as-prepared PAN-based zwitterionic copolymer was blended with polyacrylonitrile to fabricate ultrafiltration membranes. Ultrafiltration experiments revealed that membrane fouling, especially irreversible membrane fouling, was remarkably reduced due to the incorporation of zwitterionic DMMSA groups. For the PAN-based zwitterionic blend membrane with a DMMSA content of 5.8 mol%, the flux recovery ratio could reach as high as 95% under simple water flushing.

Antifouling ultrafiltration membrane composed of polyethersulfone and sulfobetaine copolymer

A new random copolymer was synthesized by reacting hydrophilic N, N-dimethyl- N-methacryloxyethyl- N-(3-sulfopropyl) (DMMSA) with hydrophobic butyl methacrylate (BMA) through a conventional radical polymerization. The as-prepared sulfobetaine copolymer (DMMSA–BMA) was blended with polyethersulfone (PES) to fabricate antifouling ultrafiltration membrane for BSA separation. The X-ray photoelectron spectroscopy analysis of blend membranes revealed concentration of sulfobetaine groups at the membrane surfaces that endowed the membrane with higher hydrophilicity and better antifouling property. For the membrane with 8.0 wt% DMMSA–BMA copolymer concentration (No. 5), irreversible fouling has been considerably reduced and the flux recovery rate of the blend membrane reached as high as 82.8%. Furthermore, the blend membrane could effectively resist BSA fouling in a wide pH range from 4.0 to 8.0.