Ammonium Propane Sulfonate Research Articles

Dipole Moment Dictates the Preferential Immobilization in Gel Electrolytes for Ah-level Aqueous Zinc-Metal Batteries.

Aqueous Zn-metal batteries are of great interest due to their high material abundance, low production cost, and excellent safety. However, they suffer from severe side reactions and notorious dendrite growth closely related to electrolytes. Here, in-situ generated zwitterionic polymers are used as gel electrolytes to overcome these problems. It is shown that anions and H2O, but not anions and cations, are preferentially immobilized at different sites of zwitterionic polymers, facilitating the free migration of Zn2+ and reducing the side reactions. This immobilization can be associated with the dipole moment of zwitterionic polymers. As a result, poly[3-dimethyl(methacryloyl oxyethyl) ammonium propane sulfonate] (PDMAPS) stands out from a series of zwitterionic polymers and outperforms the other candidates in electrochemical performance. The symmetric cells using PDMAPS smoothly operate ~9000 h at 0.5 mA cm-2 for 0.5 mAh cm-2, much better than the controls. Moreover, PDMAPS enables an Ah-level pouch cell for continuous cycling. These results not only benefit the rational molecular design of advanced electrolytes, but also demonstrate the promising potential of zwitterionic polymers in aqueous Zn-metal batteries.

Asymmetrical surface-modified polyester/cotton fabrics for temperature-adaptive moisture and thermal management of human body

Personal moisture and thermal management fabrics that can regulate skin temperature are highly desired for improving human comfort and performance. Here, a symmetric surface modified polyester/cotton fabric (Janus T/C fabric) exhibiting exceptional temperature-adaptive personal moisture and thermal managements was developed. This was achieved by integrating two distinct temperature-sensitive hydrophobic/hydrophilic transition materials through single-sided spray coating technique and in-situ ultraviolet-induced free radical polymerization in 60/40 polyester/cotton blend fabric (T/C fabric, composed of 60 % cotton and 40 % polyester fibers). 2-(2-methoxyethoxy) ethoxyethyl-methacrylate (MEO2MA) was utilized to create lower critical solution temperature (LCST) polymer, while N, N-dimethyl (methacryloylethyl) ammonium propane sulfonate (DMAPS) formed an upper critical solution temperature (UCST) polymer on T/C fabric surface. Fabric’s surface demonstrated a reversible transition in hydrophobicity/hydrophilicity in response to environmental temperature changes. The distinct hydrophobic and hydrophilic surfaces configuration resulted in a remarkable wettability gradient, significantly increased moisture permeability to 6792.5 g/m2·24 h—an increase of 1132.1 g/m2·24 h compared to the 60/40 T/C fabric at 40 °C. Moreover, the Janus T/C fabric provided practical temperature adaptation benefits, offering a cooling effect of approximately 1.2 °C in hot environments and a warming effect of approximately 1.0 °C in cold conditions. These thermal responsive properties make the asymmetric surface-modified polyester/cotton fabric an ideal choice for personalized moisture and thermal management, ensuring optimal comfort across varying temperatures.

Cellulose nanocrystal thermal smart molecular brushes with upper critical aggregation temperature

Grafting thermo-responsive polymers onto cellulose nanocrystals (CNCs) and achieving critical temperature regulation has drawn significant research interest. The thermal transition behavior of CNCs can be controlled by adjusting the polymer molecular brushes on the CNCs surface. We synthesized poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA) grafted CNCs via surface-initiated reversible addition–fragmentation chain transfer, followed by modifying PDMAEMA brushes into poly-3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate (PDMAPS) brushes via quaternization. The critical temperature was regulated by modifying and grafting of poly (ethylene glycol) methacrylate. Found the thermal stimulus-responsive type and transition point of CNCs can be controlled by adjusting the surface molecular brushes. Ultraviolet-visible spectroscopy and dynamic light scattering analyses indicated that CNC–PDMAEMA aggregated above 70 °C, whereas CNC–PDMAPS aggregated below 31 °C. The thermo-responsive materials based on CNCs exhibited a conversion from a lower critical aggregation temperature to an upper critical aggregation temperature (UCAT) type. CNC–PDMAPS–mPEG was obtained by modifying and grafting for UCAT to be regulated to approximately 37 °C, which is close to the human body temperature. CNC–PDMAPS and CNC–PDMAPS–mPEG exhibited only microscopic alterations and could encapsulate and release substances. Therefore, they demonstrate considerable potential for biomedical applications.

Multiresponsive Keratin-Polysulfobetaine Conjugate-Based Micelles as Drug Carriers with a Prolonged Circulation Time.

A protein-polymer conjugate combines the chemical properties of a synthetic polymer chain with the biological properties of a protein. In this study, the initiator terminated with furan-protected maleimide was first synthesized through three steps. Then, a series of zwitterionic poly[3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate] (PDMAPS) was synthesized via atom transfer radical polymerization (ATRP) and optimized. Subsequently, well-controlled PDMAPS was conjugated with keratin via thiol-maleimide Michael addition. The keratin-PDMAPS conjugate (KP) could self-assemble in an aqueous solution to form micelles with low critical micelle concentration (CMC) values and good blood compatibility. The drug-loaded micelles exhibited triple responsiveness to pH, glutathione (GSH), and trypsin under tumor microenvironments. In addition, these micelles showed high toxicity against A549 cells while low toxicity on normal cells. Furthermore, these micelles performed prolonged blood circulation.

A Thermal-Responsive Zwitterionic Polymer Gel as a Filtrate Reducer for Water-Based Drilling Fluids.

It is crucial to address the performance deterioration of water-based drilling fluids (WDFs) in situations of excessive salinity and high temperature while extracting deep oil and gas deposits. The focus of research in the area of drilling fluid has always been on filter reducers that are temperature and salt resistant. In this study, a copolymer gel (PAND) was synthesized using acrylamide, N-isopropyl acrylamide, and 3-dimethyl (methacryloyloxyethyl) ammonium propane sulfonate through free-radical polymerization. The copolymer gel was then studied using FTIR, NMR, TGA, and element analysis. The PAND solution demonstrated temperature and salt stimulus response characteristics on rheology because of the hydrophobic association effect of temperature-sensitive monomers and the anti-polyelectrolyte action of zwitterionic monomers. Even in conditions with high temperatures (180 °C) and high salinities (30 wt% NaCl solution), the water-based drilling fluid with 1 wt% PAND displayed exceptional rheological and filtration properties. Zeta potential and scanning electron microscopy (SEM) were used to investigate the mechanism of filtration reduction. The results indicated that PAND could enhance bentonite particle colloidal stability, prevent bentonite particle aggregation, and form a compact mud cake, all of which are crucial for reducing the filtration volume of water-based drilling fluid. The PAND exhibit excellent potential for application in deep and ultra-deep drilling engineering, and this research may offer new thoughts on the use of zwitterionic polymer gel in the development of smart water-based drilling fluid.

Enzymatic construction of temperature-responsive PDMAPS-decorated textiles for oil-water separation

In view of the frequent occurrence of oil-containing pollutant discharge events, many optimal strategies for oil-water separation were proposed. However, the large-scale application of these strategies is severely limited by the lack of environmental unfriendliness and intelligent response capability. To address these issues, we developed a thermo-responsive fabric with switchable wettability that can be applied for efficient oil-water separation by an eco-friendly enzymatic method. Briefly, 3-(trimethoxysilyl) propyl methacrylate (KH-570) and boron nitride (BN) nanosheets were introduced to the surfaces of cotton fabric, followed by enzymatic graft polymerization of N,N-dimethyl (methacryloylethyl) ammonium propane sulfonate (DMAPS) onto the fibers using horseradish peroxidase (HRP). Thanks to the switchable wettability of the composite layer on the yarn surfaces, oil and water can pass through the cotton fabric at the temperatures below and above 28 °C, respectively, realizing highly efficient oil-water separation. The resulting temperature-responsive textiles exhibit encouraging separation performance, and the separation efficiency, oil flux, and water flux reach as high as 95%, 542.57 L·h−1m−2, and 477.26 L·h−1m−2, respectively. Meanwhile, the cyclic separation capability, acid-alkali tolerance, and mechanical friction stability of the composite textiles are encouraging. The present work provides an alternative for construction of oil-water separation materials, which inspires further research on the smart oil-water separation strategies.

Cytocompatible, soft and thick brush-modified scaffolds with prolonged antibacterial effect to mitigate wound infections.

Biomedical device or implant-associated infections caused by pathogenic bacteria are a major clinical issue, and their prevention and/or treatment remains a challenging task. Infection-resistant antimicrobial coatings with impressive cytocompatibility offer a step towards addressing this problem. Herein, we report a new strategy for constructing highly antibacterial as well as cytocompatible mixed polymer brushes onto the surface of 3D printed scaffold made of biodegradable tartaric acid-based aliphatic polyester blends. The mixed brushes were nothing but a combination of poly(3-dimethyl-(methacryloyloxyethyl) ammonium propane sulfonate) (polyDMAPS) and poly((oligo ethylene glycol) methyl ether methacrylate) (polyPEGMA) with varying chain length (n) of the ethylene glycol unit (n = 1, 6, 11, and 21). Both homo and copolymeric brushes of polyDMAPS with polyPEGMA exhibited antibacterial efficacy against both Gram positive and Gram negative pathogens such as E. coli (Escherichia coli) and S. aureus (Staphylococcus aureus) because of the combined action of bacteriostatic effects originating from strongly hydrated layers present in zwitterionic (polyDMAPS) and hydrophilic (polyPEGMA) copolymer brushes. Interestingly, a mixed polymer brush comprising polyDMAPS and polyPEGMA (ethylene glycol chain unit of 21) at 50/50 ratio provided zero bacterial growth and almost 100% cytocompatibility (tested using L929 mouse fibroblast cells), making the brush-modified biodegradable substrate an excellent choice for an infection-resistant and cytocompatible surface. An attempt was made to understand their extraordinary performance with the help of contact angle, surface charge analysis and nanoindentation study, which revealed the formation of a hydrophilic, almost neutral, very soft surface (99.99% reduction in hardness and modulus) after modification with the mixed brushes. This may completely suppress bacterial adhesion. Animal studies demonstrated that these brush-modified scaffolds are biocompatible and can mitigate wound infections. Overall, this study shows that the fascinating combination of an infection-resistant and cytocompatible surface can be generated on biodegradable polymeric surfaces by modulating the surface hardness, flexibility and hydrophilicity by selecting appropriate functionality of the copolymeric brushes grafted onto them, making them ideal non-leaching, anti-infective, hemocompatible and cytocompatible coatings for biodegradable implants.

Novel Thermosensitive-co-Zwitterionic Sulfobetaine Gels for Metal Ion Removal: Synthesis and Characterization.

Zwitterionic betaine polymers are promising adsorbents for the removal of heavy metal ions from industrial effluents. Although the presence of both negative and positively charged groups imparts them the ability to simultaneously remove cations and anions, intra- and/or inter-chain interactions can significantly reduce their adsorption efficiencies. Therefore, in this study, novel gels based on crosslinked co-polymers of thermosensitive N-isopropylacrylamide (NIPAAM) and zwitterionic sulfobetaine N,N-dimethylacrylamido propyl ammonium propane sulfonate (DMAAPS) were synthesized, characterized, and evaluated for ion removal. Fourier-transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) analyses confirmed the success of the co-polymerization of NIPAAM and DMAAPS to form poly(NIPAAM-co-DMAAPS). The phase transition temperature of the co-polymer increased with increasing DMAAPS content in the co-polymer, indicating temperature-dependent amphiphilic behavior, as evidenced by contact angle measurements. The ion adsorption analyses of the poly(NIPAAM-co-DMAAPS) gels indicated that co-polymerization increased the molecular distance and weakened the interaction between the DMAAPS-charged groups (SO3− and N+), thereby increasing the ion adsorption. The results confirmed that, with a low concentration of DMAAPS in the co-polymer gels (~10%), the maximum amount of Cr3+ ions adsorbed onto the gel was ~58.49% of the sulfonate content in the gel.

Zwitterionic dual-network strategy for highly stretchable and transparent ionic conductor

The development of flexible electronic devices depends on the research of stretchable conductive materials. In this work, we report a green and transparent ionic conductor with high stretchability based on green deep eutectic solvents (DESs) and biocompatible zwitterionic polymer. The dual-network (DN) strategy was achieved by two-step UV-initiated polymerization, and the DN ion gels consisting of the physically cross-linked zwitterionic poly(3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate) (PDMAPS) and chemically cross-linked poly(2-hydroxyethyl methacrylate) (PHEMA) were prepared, using choline chloride/ethylene glycol (ChCl/EG) DESs as solvents. The prepared DN ion gels present outstanding tensile properties (breaking strain over 1000%), high transparency (>90%), good room temperature ionic conductivity (0.315 S m−1), and good fatigue resistance. In addition, due to the ultra-low volatility and low freezing point of the ChCl/EG DESs, the DN ion gel shows high stability and frost resistance (−60 °C). Finally, the performance of the DN ionic gel-based flexible strain sensor is investigated to evaluate its application potential in wearable flexible electronic devices. The DN ion gel strain sensor can sensitively and stably monitor human motions. The outstanding characteristics such as non-toxicity and biocompatibility of both the conductive filler and polymer matrix for preparing the DN ion gels in this work provide a new view for the development of green flexible conductive devices with high performance and multiple functions.

Properties of Zwitterionic Sulfobetaine Gels Containing Different Numbers of Methylene Units

The present research was performed aiming to develop gel with the characteristic of reversible thermosensitive in adsorbing heavy metal ions from its solution. There were three gels used in this study to adsorb heavy metal ion from salt solution provided Zn(NO3)2; copolymer gel consisting of zwitterionic betaine N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS), N,N-dimethyl(acrylamidopropyl)ammonium butane sulfonate (DMAABS), and DMAAPS copolymerized with thermosensitive N-isopropylacrylamide (NIPAM) gels. The aforementioned gels were employed to examine its ability in adsorbing and swelling after being synthesized through free radical polymerization before being affected by methylene spacer number, copolymerization, and temperature given. This research found that as the temperature increases, the ability of the gel in adsorbing the ions decreases. In the case of DMAAPS and DMAABS gel, the swelling degree value increases when the temperature also increases. Meanwhile, sulfobetaine which has larger spacer has higher adsorption ability but not with its swelling degree. In spite of having more spacer than DMAAPS, DMAABS found to have the smallest swelling degree value. In addition, NIPAM-co-DMAAPS was found to have both the highest adsorption ability and swelling degree value. Even though copolymer has less amount of sulfobetaine than DMAAPS and DMAABS gels’, the copolymer gel was found to have higher ability of adsorption as many as ten times of other gels.

The Properties of Thermosensitive Zwitterionic Sulfobetaine NIPAM-<i>co</i>-DMAAPS Polymer and the Hydrogels: The Effects of Monomer Concentration on the Transition Temperature and Its Correlation with the Adsorption Behavior

The properties of N-isopropylacrylamide copolymerized with N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate [poly(NIPAM-co-DMAAPS)] prepared with various monomer ratios such as transition temperature, molecular structure, viscosity were systematically investigated in water and Zn(NO3)2 solution. Poly(NIPAM-co-DMAAPS) in water and Zn(NO3)2 solution exhibited a phase transition with a lower critical solution temperature (LCST). The higher ratio of NIPAM monomer in poly(NIPAM-co-DMAAPS), the lower the LCST of the polymer. Furthermore, the transition temperature of poly(NIPAM-co-DMAAPS) with a lower NIPAM concentration were not confirmed both in water nor Zn(NO3)2 solution. The more increase the NIPAM concentration used in the preparation, the more increase the polymer viscosity. Moreover, the more increase the adsorption amount of ions onto the gel, the more increase the polymer transmittance as well.

Correlating properties between sulfobetaine hydrogels and polymers with different carbon spacer lengths

The ion-adsorption and swelling behaviors of sulfobetaine hydrogels composed of N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS) and N,N-dimethyl-(acrylamidopropyl)ammonium butane sulfonate (DMAABS) at various temperatures and cross-linker concentrations were investigated. We demonstrate a correlation between ion adsorption onto the DMAAPS gel and its degree of swelling. Conversely, in the DMAABS gel, the cross-linker concentration and temperature showed no effect on gel adsorption ability and swelling behavior. Furthermore, maximum ion adsorption onto the DMAAPS gel was strongly correlated with the transition temperature of the polymer. The carbon spacer length between the sulfobetaine charged groups mediates the interactions between the quaternary ammonium (R4N+) and sulfonate groups (SO3−) that contribute to their adsorption, swelling, and transition behavior.

Preparation of Novel Zwitterionic Monolith for Capillary Electrochromatography and Nano LC–MS Applications

Herein, a zwitterionic organic polymer monolithic stationary phase was prepared based on the in situ thermal-initiated copolymerizing 3-dimethyl-(3-(N-methacrylamido) propyl) ammonium propane sulfonate (DMMPPS) and pentaerythritol triacrylate (PETA) in a binary porogenic solvent consisting of MeOH and H2O. An HILIC/RP dual separation mechanism was observed on this optimised poly(DMMPPS-co-PETA) monolithic column and the composition of the mobile phase corresponding to the transition from the HILIC to the RP mode was around 30% ACN in water. The proposed monolithic column was successfully applied to separate 12 polar neurotransmitters in a nano LC–MS mode. About ~ 27 μm plate height (corresponding to column efficiency of ~ 93,000 plates/m) was obtained at the linear velocity of 1 mm/s. Meantime, the DMMPPS-based monolith exhibited good mechanical stability and excellent separation performance for nucleic acid bases, nucleosides and nucleotides for capillary electrochromatography (CEC). Relative standard deviations (RSD%) of the retention times for five nucleic acid bases and nucleosides were in the range of 0.15–0.42% (run-to-run, n = 3) and 2.63–4.50% (column-to-column, n = 3), respectively. Our work demonstrated that the zwitterionic monolith columns could be an effective separation tool for analysis of hydrophilic substances both on the HI-CEC and nano LC–MS mode.

Reversible Adsorption-Desorption of Zn (II) and Pb (II) in Aqueous Solution by Thermosensitive-Sulfobetaine Gel

Copolymer gel contains zwitterionic betaine N,N-dimethyl(acrylamidopropyl) ammonium propane sulfonate (DMAAPS) and thermosensitive N-isopropylacrylamide (NIPAM). Later, they were employed as reversible Zn (II) and Pb (II) adsorption-desorption in aqueous solution. The effects of temperature, monomer, cross-linker concentration, and type of ions on the swelling degree, and the adsorption amount of Zn (II) and Pb (II) ions onto the gel were investigated. In addition, the adsorption-desorption reversibility of ions was also examined. The adsorption ability and swelling degree of the gel were significantly influenced by temperature, monomer, and cross-linker concentrations. The amount of ions adsorbed onto the gel was inversely proportional to its temperature at various monomer concentrations. The swelling degree of the gel with NIPAM to DMAAPS molar ratio of 9:1 and 8:2 decreased with the increase of the temperature. However, for the gel prepared with NIPAM to DMAAPS molar ratio of 7:3, the swelling degree increased significantly as the temperature increased. It was obtained that the swelling degree of the gel in Zn(NO3)2 solution was higher than the swelling degree of the gel in Pb(NO3)2 solution. In contrast, the amount of ions adsorbed onto the gel in Zn(NO3)2 solution was slightly lower than in Pb(NO3)2 solution. Copolymer gel prepared with NIPAM to DMAAPS molar ratio of 8:2 exhibited the highest adsorption ability and swelling degree in Zn(NO3)2 and Pb(NO3)2 solutions. In addition, the copolymer gel of NIPAM-co-DMAAPS showed the reversible adsorption-desorption ability toward ions up to three cycles.

Preparation of monometallic and bimetallic alloy nanoparticles stabilized with sulfobetaine-based block copolymer and their catalytic activities

Zwitterionic sulfobetaine-containing diblock copolymer, poly(ethylene glycol)methyl ether-block-poly[3-dimethyl(methacryloyloxy ethyl)ammonium propane sulfonate] (MPEG-b-PSBMA), was successfully synthesized and utilized as a stabilizer to prepare mono- and bimetallic nanoparticles. Precursor poly(ethylene glycol)methyl ether-block-poly[2-(N-dimethylamino)ethyl methacrylate] (MPEG-b-PDMA) diblock copolymer was first synthesized via atom transfer radical polymerization. PDMA blocks were reacted with 1,3-propanesultone to obtain MPEG-b-PSBMA diblock copolymer. Spherical monometallic gold (Au), platinum (Pt) and bimetallic alloy gold/platinum (Au/Pt), gold/silver (Au/Ag), and silver/platinum (Ag/Pt) nanoparticles (with a diameter below 8.0 nm) were synthesized in aqueous media via sonochemical method using diblock copolymer as stabilizer. The zwitterionic sulfobetaine block copolymer provided thermodynamic (5 days at 65 °C) and kinetic (1 year at 25 °C) stability to the synthesized NPs without aggregation. Zwitterionic PSBMA blocks of MPEG-b-PSBMA diblock copolymer showed an upper critical solution temperature (UCST) in aqueous media. This thermo-responsive block copolymer provided better stabilization to metal NPs as compared with MPEG and PSBMA homopolymers. The structures of bi- and monometallic NP dispersions were characterized by measuring surface plasmon resonance and transmission electron microscopy. The prepared metal NP/polymer dispersions showed good catalytic activities (Ag/Pt > Au/Ag > Au > Au/Pt > Pt) in the reduction of p-nitrophenol to p-aminophenol.

Preparation and Evaluation of Zwitterionic Polymer Coated Capillary Columns for Analysis of Proteins by Capillary Electrophoresis

The ability to manipulate and control the inner surface properties of silica capillary is of crucial importance for analysis of proteins by capillary electrophoresis. In this work, surface-initiated atom transfers radical polymerization (ATRP) of zwitterionic 3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate (DMAPS) is employed to tailor the functionality of silica capillary in a well-controlled manner. The structure of the coating and the protein separation performance were investigated. The results confirmed that the P(DMAPS) grafting can substantially enhance the performance of the capillary columns. With the versatility of surface-initiated ATRP and the excellent performance of zwitterionic polymer chains, the zwitterionic polymer coated capillary columns can be readily tailored for analysis of proteins by capillary electrophoresis.

One-Pot and One-Step Fabrication of Salt-Responsive Bilayer Hydrogels with 2D and 3D Shape Transformations.

Bilayer hydrogels are one of the most promising materials for use as soft actuators, artificial muscles, and soft robotic elements. Therefore, the development of new and simple methods for the fabrication of such hydrogels is of particular importance for both academic research and industrial applications. Herein, a facile, one-pot, and one-step methodology was used to prepare bilayer hydrogels. Specifically, several common monomers, including N-isopropyl acrylamide, acrylamide, and N-(2-hydroxyethyl)acrylamide, as well as two salt-responsive zwitterionic monomers, 3-(1-(4-vinylbenzyl)-1H-imidazol-3-ium-3-yl)propane-1-sulfonate (VBIPS) and dimethyl-(4-vinylphenyl)ammonium propane sulfonate (DVBAPS), were chosen and employed with different combinations and ratios to understand the formation and structural tunability of the bilayer hydrogels. The results indicated that a salt-responsive zwitterionic-enriched copolymer, which could precipitate from water, plays a dominant role in the formation of the bilayer structure and that the ratio between the common monomer and the zwitterionic monomer had a significant effect on the structure. Due to the salt-responsive properties of polyVBIPS and polyDVBAPS, the resultant bilayer hydrogels exhibited excellent bidirectional bending properties in response to the salt solution. With the optimal monomer pair and ratio determined, the bend of the hydrogel could be reversed from ∼-360 to ∼266° in response to a switch between water and a 1.0 M NaCl solution. Additionally, this method was further used to fabricate small-scaled patterns with structural and compositional distinction in two-dimensional hydrogel sheets. These two-dimensional hydrogel sheets exhibited complex and reversible three-dimensional shape transformations due to the different bending behaviors of the patterned hydrogel stripes under the action of an external stimulus. This work provides greater insight into the mechanism of the one-step, one-pot method fabrication of bilayer hydrogels, demonstrates the ability of this method for the preparation of small-scale patterns in hydrogel sheets to endow the complex with a three-dimensional shape transformation capability, and hopefully opens up a new pathway for the design and fabrication of smart hydrogels.

Biologically Functional Ultrathin Films Made of Zwitterionic Block Copolymer Micelles.

We report the preparation of ultrathin coatings of zwitterionic block copolymer micelles and a comparison of their protein adsorption, adhesiveness, and antibacterial properties. Zwitterionic block copolymer micelles were obtained through pH-induced self-assembly of poly[3-dimethyl(methacryloyloxyethyl)ammonium propanesulfonate- b-2-(diisopropylamino)ethyl methacrylate] (βPDMA- b-PDPA) at pH 7.5. βPDMA- b-PDPA micelles with zwitterionic βPDMA-corona and pH-responsive PDPA-core were then used as building blocks to prepare layer-by-layer (LbL) assembled multilayer films together with hyaluronic acid (HA), tannic acid (TA), or poly(sodium 4-styrenesulfonate) (PSS). Protein adsorption tests showed that 3-layer βPDMA- b-PDPA micelles/HA films were the most effective to reduce the adhesion of BSA, lysozyme, ferritin, and casein. In contrast, βPDMA- b-PDPA micelles/TA films were the most attractive surfaces for protein adsorption. Bacterial antiadhesive tests against a model Gram-negative bacterium, Escherichia coli, and a model Gram-positive bacterium, Staphylococcus aureus, were in good agreement with the protein adsorption properties of the films. The differences in the antiadhesive properties between these three different film systems are discussed within the context of chemical nature and the functional chemical groups of the polyanions, layer number, and surface morphology of the films. Multilayers were found to lose their antiadhesiveness in the long term. However, by taking advantage of the pH-responsive hydrophobic micellar cores, we show that an antibacterial agent could be loaded into the micelles and multilayers could exhibit antibacterial activity in the long term especially at moderately acidic conditions. In contrast to antiadhesive properties, no significant differences were recorded in the antibacterial properties between the different film types.

Construction of lubricant composite coating on Ti6Al4V alloy using micro-arc oxidation and grafting hydrophilic polymer

To improve the tribological properties of Ti6Al4V alloy to realize the application in artificial joints, a novel composite coating was designed and fabricated on its surface through the combination of two different surface modification techniques—micro-arc oxidation (MAO) and grafting hydrophilic polymer. The characterizations of morphologies and composition of MAO layer were examined using scanning electron microscopy (SEM), energy dispersive spectroscope (EDS) and X-ray diffraction (XRD). It was found that a TiO2 layer displaying uniform porous structure formed on the surface based on the optimal MAO parameters of an oxidation voltage of 450 V and an oxidation time of 60 min. After grafting 3-dimethyl(3-(N-methacrylamido)propyl) ammonium propane sulfonate (MPDSAH), Fourier-transform infrared spectroscopy with attenuated total reflection (FT-IR/ATR) and wettability test demonstrated the successful modification. Tribological performance of composite coating-modified Ti6Al4V alloy in water exhibited the low friction coefficient of 0.13 and favorable wear resistance.

Use of Sulfobetaine-Based Block Copolymer as Stabilizer in Silver Nanoparticle Production and Catalytic Activity Studies.

A zwitterionic sulfobetaine-based diblock copolymer was successfully synthesized and used in the preparation and stabilization of Ag nanoparticles (AgNPs). For the related block copolymer, a precursor AB type diblock copolymer was synthesized via atom transfer radical polymerization by using a MPEG-based ATRP macroinitiator and 2-(N-dimethylamino)ethyl methacrylate (DMA) comonomer. Tertiary amine residues of PDMA blocks in poly(ethylene glycol) methyl ether-b-poly[2-(N-diethylamino)ethyl methacrylate] (MPEG-b-PDMA) precursor was then converted to polybetaine structures by reacting with 1,3-propanesultone to obtain poly(ethylene glycol) methyl ether-b-poly[3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate] (MPEG-b-PβDMA) derivative. The resulting block copolymer was successfully used as stabilizer in the chemical and sonochemical synthesis of spherical AgNPs with a diameter in the range of 7.9-9.3 nm. The average diameter of AgNPs synthesized by sonochemical method was smaller than those synthesized by chemical method. The MPEG-b-PβDMA diblock copolymer was determined to be a good stabilizer for AgNPs. The AgNPs dispersion was stable for more than 5 months without any flocculation at room temperature. The catalytic activity of polymer-AgNP dispersion was also investigated in the reduction of p-nitrophenol to p-aminophenol and was found to be quite effective.