Methacryloyloxy Ethyltrimethylammonium Research Articles

An antibacterial biologic patch based on bacterial cellulose for repair of infected hernias

Infection-associated complications and repair failures and antibiotic resistance have emerged as a formidable challenge in hernia repair surgery. Consequently, the development of antibiotic-free antibacterial patches for hernia repair has become an exigent clinical necessity. Herein, a GBC/Gel/LL37 biological patch (biopatch) with exceptional antibacterial properties is fabricated by grafting 2-Methacryloyloxyethyl trimethylammonium chloride (METAC), a unique quaternary ammonium salt with vinyl, onto bacterial cellulose (GBC), followed by compounding with gelatin (Gel) and LL37. The GBC/Gel/LL37 biopatch exhibits stable swelling capacity, remarkable mechanical properties, flexibility, and favorable biocompatibility. The synergistic effect of METAC and LL37 confers upon the GBC/Gel/LL37 biopatch excellent antibacterial efficacy against Staphylococcus aureus and Escherichia coli, effectively eliminating invading bacteria without the aid of exogenous antibiotics in vivo while significantly reducing local acute inflammation caused by infection. Furthermore, the practical efficacy of the GBC/Gel/LL37 biopatch is evaluated in an infected ventral hernia model, revealing that the GBC/Gel/LL37 biopatch can prevent the formation of visceral adhesions, facilitate the repair of infected ventral hernia, and effectively mitigate chronic inflammation. The prepared antibacterial GBC/Gel/LL37 biopatch is very effective in dealing with the risk of infection in hernia repair surgery and offers potential clinical opportunities for other soft injuries, exhibiting considerable clinical application prospects.

Enhanced dewaterability of sewage sludge by grafted cationic lignin-based flocculants

Lignin-based flocculants are widely used for wastewater purification, but their application in sludge dewatering has not yet been documented. In this study, a novel cationic lignin-based flocculant named LS-g-CPA was prepared by grafting cationic polyacrylamide (CPA) synthesized from methacryloyloxy ethyltrimethyl ammonium chloride (DMC) and acrylamide (AM) onto sodium lignosulfonate (LS), and its roles and underlying mechanisms in sludge conditioning were investigated. The results showed that LS-g-CPA effectively improved the dewaterability of sludge, reducing the filtration resistance and filter cake moisture content of sludge from 0.61 ± 0.05 × 1012 m/kg to 0.14 ± 0.02 × 1012 m/kg and 85.64 ± 0.25 % to 76.84 ± 0.41 %, respectively. The dewatering performance of LS-g-CPA was positively correlated with the DMC/AM ratio. The quaternary ammonium groups brought by DMC disrupted the reticular structure of extracellular polymeric substances, exposing hydrophobic residues and releasing bound water. Nevertheless, the key to LS-g-CPA for improving sludge dewatering lies more in the amphoteric flocculant properties that enhance sludge flocculation and the octopus-type structure that provides good drainage channels. This study reveals that lignin-based flocculants are effective in improving the dewaterability of sludge, which provides direct evidence for their application in sludge dewatering.

Continuous-Flow Grafting of LENFLOC™ Coagulant for Water Treatment toward Circular Economy

This study investigated the efficiency of LENFLOC™ production using a microwave-assisted continuous-flow grafting process. The study discussed the contribution of plant-based coagulants for water and wastewater treatment toward the circular economy in water treatment. Lentil waste extract was used to produce LENFLOC™ using (2-methacryloyloxyethyl) trimethyl ammonium chloride with 75 wt.% on H2O as a chain monomer and cerium ammonium nitrate (≥98%) as an initiator. The continuous flow grafting process was conducted at a constant flowrate of 60 mL/min and reaction time of 30 s. The process was optimised using RSM to obtain optimum conditions of process factors. Characterisation studies were conducted using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray. A comparison study was performed using a Jar test with LENFLOC™, lentil waste extract, and a polymer as coagulants. The results obtained show that the continuous-flow grafting process was efficient with an optimum grafting percentage of 330%. The characterisation studies confirmed the grafting process. A 99% turbidity removal rate was achieved with LENFLOC™ as a coagulant with a lower dosage compared to the lentil waste extract. Furthermore, microscope imaging showed improved floc compaction when using LENFLOC™ as a coagulant. The continuous-flow grafting process has been shown to be effective; therefore, its potential for upscaling the process is possible.

Evaluation of the nanoplastics removal by using starch-based coagulants: Roles of the chain architecture and hydrophobicity of the coagulant

Four starch-based coagulants with similar charge densities but different chain architectures and hydrophilicities were designed and fabricated. These are a linear and hydrophilic coagulant, St-CTA (Starch-3-chloro-2-hydroxypropyl triethyl ammonium chloride); a graft and hydrophilic coagulant, CS-AM-DMC (cationic starch-graft-poly[2-methacryloyloxyethyl trimethyl ammonium chloride and acrylamide]); and two graft and partially hydrophobic coagulants, CS-AM-DML (cationic starch-graft-poly[methacrylic acid 2-(benzyldimethylaminio) ethyl chloride and acrylamide]) and CS-AM-DMR (cationic starch-graft-poly[2-(methacryloyloxy)-N,N-dimethyl-N-alkyl ammonium chloride and acrylamide]) with aromatic and n-octane groups respectively. These starch-based coagulants in conjunction with polysilicic acid were employed in a current major environmental challenge which is to efficiently remove nano-sized plastics (NPs) from water. NPs of polystyrenes, polymethyl methacrylates and polyvinylchlorides were removed from different water sources under various conditions of pH and salinity. The effects of the chain architectures and hydrophilicities of the starch-based coagulants on the NPs removal have been investigated in detail. According to experimental evidence, three graft starch-based coagulants exhibited higher NPs removal efficiencies and better flocs properties than the linear St-CTA. This was attributed to the superiority of the graft chain architecture in the graft starch-based coagulants causing higher charge neutralization efficiencies in coagulative removal of NPs. In the three graft starch-based coagulants, CS-AM-DMR and CS-AM-DML with partially hydrophobic structures were more effectively to remove three NPs than CS-AM-DMC, and produced large, compact, durable and rapidly regrown flocs, due to the synergistic effects of charge neutralization and hydrophobic association. The interaction energies between NPs and the coagulants obtained from the extended Derjaguin-Landau-Verwey-Overbeek theory further confirmed that CS-AM-DMR and CS-AM-DML could achieve faster coagulation and thus higher efficiency in NPs removal. In addition, the NPs removal efficiency increased in acidic and highly saline solutions. These results obtained are of importance in guiding the design and selection of suitable polymeric coagulants for efficiently treating target contaminants in water.

Bifunctional Polymer Brush Reactor for In Situ Synthesis of Hollow Silica-Supported Gold Nanocatalysts.

Gold nanoparticles (AuNPs) on carriers have received wide attention as catalysts as a result of their excellent stability and catalytic performance. Herein, we report the design and synthesis of hollow silica-supported gold nanocatalysts (SNPs@AuNPs) composed of highly dispersed AuNPs with approximately 4.30 nm using an in situ colloidal polyelectrolyte template strategy. The monodisperse polystyrene nanospheres accompanied by poly[(2-methacryloyloxyethyl)trimethylammonium chloride] brushes were first synthesized. Subsequently, the facile polymer-brush-engaged strategy for the synthesis of hollow SNPs@AuNPs involves in situ reduction of AuNPs, hydrolytic condensation of silica, and a chemical etching process. In combination with dynamic light scattering, transmission electron microscopy, small-angle X-ray scattering, X-ray powder diffraction, and Fourier transform infrared spectroscopy, the as-obtained polymer brushes were proven as effective versatile nanoreactors for the synthesis of AuNPs and silica nanoparticles without any catalysts. Benefiting from the structural advantages, the resultant hollow SNPs@AuNPs manifested superior catalytic activity and reusability for the reduction of p-nitrophenol by sodium borohydride in aqueous solution. With a delicate design, we believe that this synthetic strategy can be extended to fabricate multifunctional nanomaterials with diverse compositions, which would be of great interest in catalysis, energy, and many other important domains.

Molecular Bottlebrushes for Immunostimulatory CpG ODN Delivery: Relationship among Cation Density, Complex Formation Ability, and Cytotoxicity.

Artificially designed short single-stranded DNA sequences containing unmethylated CG (CpG ODNs) are agonists for toll-like receptor 9 (TLR9); thus, they have great potential as vaccine adjuvants for cancer immunotherapy and preventing infectious diseases. To deliver effectively CpG ODNs into cells bearing TLR9, nanoparticle polyion complexes of cationic polymers that are able to ingest multiple CpG ODN molecules have been developed; however, their structures and synthesized polycations are hard to control and bioincompatible, respectively. To solve these issues, we designed cationic molecular bottlebrushes (CMBs) with branches that are made from copolymers of 2-methacryloyloxyethyl phosphorylcholine and 2-methacryloyloxyethyl trimethylammonium chloride. Several instrumental methods were carried out to determine the structure of a CMB and its complex with CpG ODNs. The complexation did not change the overall shape of the original CMB, and the bound CpG ODNs were captured by the outer layer of the CMB. The moderation of cations was important to reduce toxicity and improve secretion of inflammatory cytokines.

Thermal Stability of Cationic Poly(3-methacryloylamino Propyl Trimethyl Ammonium Chloride) in Salt Solution

In this paper the thermal stability properties of poly(3-methacryloylamino propyl trimethyl ammonium chloride) (PMAPTAC) with a series of molecular weights in various salt solutions were investigated by monitoring the apparent viscosity and viscosity retention rate with aging time, for the first time to our knowledge. Secondly, the thermal stability properties of poly(methacryloyloxy ethyl trimethyl ammonium chloride) (PDMC) solution was studied and compared with that of the PMAPTAC solution under the same conditions. The results showed that the viscosity retention rate of PMAPTAC/salt solutions with salinities from 40 g/L to 200 g/L at 85 °C were about 60%, indicating that PMAPTAC had good temperature and salt resistance. Besides, the temperature and salt resistance of PMAPTAC with 0.62 dL/g was better than that of PMAPTAC with 7.55 dL/g under the conditions of this study. In addition, the viscosity retention rate of PDMC/salt solution with the same intrinsic viscosity as PMAPTAC/salt solution was 45%, indicating that compared with PDMC, the PMAPTAC with viscosity retention rate of 60% had better temperature and salt resistance. We suggest the results obtained in this study will not only fill the current gaps in the research of the temperature and salt tolerance properties of PMAPTAC, but also provide support for the potential application of PMAPTAC products in high-temperature and high-salt environments.

A roadmap for hydrogel-based quasi-solid electrolyte preparation for use in dye-sensitized solar cell

Although the use of quasi-solid electrolytes in dye-sensitized solar cells (DSSCs) is viewed as a solution to the stability problem of DSSCs, the network structure effect on the DSSCs’ performance has not been studied in detail. Structurally different hydrogels poly (2-methacryloyloxyethyl trimethylammonium chloride-co-acrylic acid) were prepared and used as quasi-solid gel electrolytes in DSSCs to investigate the network structure effect of hydrogels on DSSC performance. The hydrogel's network structure was changed using different amounts of cross-linkers during synthesis. Five quasi-solid electrolytes were prepared from the hydrogels. The increased cross-linking of quasi-solid electrolytes during synthesis raised conductivity from 0.102 to 0.144 S m−1. Despite expectations, it was observed that the energy conversion efficiency of DSSCs does not follow the rising trend in conductivity, as it rises from 6.57% to 6.62% and then decreases to 5.17%, with increased cross-linking. Moreover, cross-linking during hydrogel synthesis defines not only the electrical properties of quasi-solid electrolytes but also the swelling, wetting, and morphological properties of the structure. Therefore, this study aimed to investigate how and which parameters affect the energy conversion efficiency of DSSCs that are prepared with quasi-solid electrolytes.

Development of dietary fiber psyllium based hydrogel for use in drug delivery applications

Keeping in view the therapeutic and gel forming role of the psyllium seed mucilage in pharmaceutical industries, herein this article, its potential has been explored for developing the drug delivery (DD) carrier. The main aim of the study was to modify the psyllium polysaccharides through grafting and crosslinking of 2-methacryloyloxyethyl trimethylammonium chloride onto psyllium to develop the hydrogels for use in DD application. Various thermal, mechanical, physiochemical, biomedical properties of the hydrogel were determined along with characterization with 13C NMR, FTIR, XRD, TGA, DSC and AFM. The release of antibiotic drug cefuroxime occurred in sustained manner and followed Fickian diffusion mechanism and was best fitted in Higuchi kinetic model. The networks showed mesh size in the range between 25.14 to 38.92 nm during the change in crosslinker content in copolymerization reaction. It has been inferred from the results that these hydrogels could be used as a potential carrier for drug delivery.

Capturing organics from municipal wastewater using a primary sludge-derived polymer

Among the numerous organics capture technologies, chemical enhanced primary treatment (CEPT) offers several distinct advantages, including low energy consumption, less oxidation of organic matter, and large-scale operation. However, CEPT currently relies heavily on metal salt-based coagulants, which have some limitations in terms of agent costs, sludge volume, and alkalinity variation. This preliminary study proposes the use of organic matter from municipal wastewater as raw materials (i.e., primary sludge) for the preparation of organic polymer, which would be used in place of conventional inorganic coagulants for organics recovery. An organic flocculant (PSBs-g-PAM-co-PDMC) was prepared by grafting DMC [(2-methacryloyloxyethyl) trimethyl ammonium chloride] and AM (acrylamide) onto the backbone of primary sludge-derived biopolymers (PSBs), which formed during the of sludge hydrothermal treatment. Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, zeta potential analysis, and gel permeation chromatography were used to characterize the chemical properties of PSBs-g-PAM-co-PDMC. These methods confirmed the incorporation of AM and DMC into the PSBs' backbone. PSBs-g-PAM-co-PDMC was used to investigate the COD (chemical oxygen demand) capture characteristics of real municipal wastewater. The results indicated that by dosing 30 mg/L PSBs-g-PAM-co-PDMC, approximately 60.0% of the COD was removed. At a low dosage (≤10 mg/L), COD can be efficiently reduced by removing predominantly particulate COD, while at a higher dosage, the further decrease of COD depends on the removal of colloidal COD. Both increasing and decreasing the pH have an effect on the COD removal mechanism. Additionally, the effluent quality and production cost were analyzed.

Dopamine Assisted Self-Cleaning, Antifouling, and Antibacterial Coating via Dynamic Covalent Interactions.

The rapid accumulation of dead bacteria or protein on a bactericidal surface can reduce the effectiveness of the modified surface and alter its biocidal activity by shielding the surface biocide functional groups, promoting microbial attachment and subsequent biofilm formation. Thus, the alteration of biocidal activity due to biofilm formation can cause serious trouble including severe infection or implant or medical device failure leading to death. Therefore, developing a smart self-cleaning surface is of great interest. Ideally, such a surface can not only kill the attached microbials but also release the dead cells and foulants from the surface under a particular incitement on demand. In this project, a sugar-responsive self-cleaning coating has been developed by forming covalent boronic ester bonds between catechol groups from polydopamine and a benzoxaborole pendant from zwitterionic and cationic polymers. To incorporate antifouling properties and enhance the biocompatibility of the coating, bioinspired zwitterionic compound 2-methacryloyloxyethyl phosphorylcholine (MPC) was chosen and benzoxaborole pendant containing zwitterionic polymer poly(MPC-st-MAABO) (MAABO: 5-methacrylamido-1,2-benzoxaborole) was synthesized. Additionally to impart antibacterial properties to the surface, a quaternary ammonium containing cationic polymer poly(2-(methacryloyloxy)ethyl trimethylammonium (META)-st-MAABO)) was synthesized. These synthesized polymers were covalently grafted to a polydopamine (PDA) coated surface by forming a strong cyclic boronic ester complex with a catechol group of the PDA layer endowing the surface with bacteria contact-killing properties and capturing specific protein. After the addition of cis-diol containing competitive molecules, i.e., saccharides/sugars, this boronic ester complex with a catechol group of PDA was replaced and the attached polymer layer was cleaved from the surface, resulting in the release of both absorbed protein and live/killed bacteria electrostatically attached to the polymer layer. This dynamic self-cleaning surface can be a promising material for biomedical applications avoiding the gathering of dead cells and debris that are typically encountered on a traditional biocidal surface.

Low-pressure UV-initiated synthesis of cationic starch-based flocculant with high flocculation performance

A kind of starch-based flocculant (starch-graft-poly[(2-methacryloyloxyethyl) trimethyl ammonium chloride], denoted St-g-PDMC-LPUV) has been synthesized by low-pressure ultraviolet initiation and was employed to remove humic acid (HA) for water purification. The physicochemical characteristics of starch and St-g-PDMC-LPUV were characterized by FT-IR, 1H NMR, XRD, TGA, SEM and BET to confirmed the successful grafting DMC onto starch. Effects of flocculant dosage, pH, the adding amount of Fe3O4, initial HA concentration and stirring speed were investigated systematically. The prepared St-g-PDMC-LPUV flocculant with non-toxic, biodegradability and environmental friendliness exhibited effective performance for removing HA from water in a wide pH range (5–10). The flocculation mechanism was attributed to the effective collision between function groups of the St-g-PDMC-LPUV flocculant and HA by charge neutralization, adsorption, bridging and patching.

Multifunctional Polymer Particles Containing Quaternary Ammonium for Antimicrobial Particulate Surfactants and Defoaming

The preparation of multifunctional polymer particles containing quaternary ammonium molecules by emulsion iodine transfer polymerization (emulsion ITP) via polymerization-induced self-assembly was proposed for the first time. Poly(2-methacryloyloxy ethyl trimethyl ammonium chloride-dimethylamino ethyl methacrylate 12 alkyl chain length)-iodide (P(MTMA-QAC12)12-I) was first synthesized by solution iodine transfer polymerization. It was simultaneously used as a macro-chain transfer agent and emulsifier in emulsion ITP. All conditions smoothly proceeded without coagulation, where the polymerization reached high conversion within only 4 h. When the methyl methacrylate-styrene (P(MMA-S)) copolymer was synthesized in the second block as P(MTMA-QAC12)12-b-P(MMA-S)462, the water contact angle of the obtained particles was close to 90°, which was the most appropriate to use as the particulate surfactant. The P(MTMA-QAC12)12-b-P(MMA-S)462 particles represented a good antimicrobial property based on the positive charge quaternary ammonium groups existing on surfaces. Using such P(MTMA-QAC12)12-b-P(MMA-S)462 nanoparticles (∼90 nm) at 1 wt %, the obtained cutting oil emulsion model represented high colloidal stability with approximately 50 μm oil droplet size without any coalescence. Moreover, foam formation was significantly reduced compared to the commercial cutting oil. According to their excellent properties, P(MTMA-QAC12)12-b-P(MMA-S)462 nanoparticles would be effectively used as a particulate surfactant in Pickering emulsion, including defoamers and antimicrobial agents.

Fabrication and cell imaging of konjac glucomannan-copper nanocluster conjugates with aggregation-induced emission

A positively charged konjac glucomannan-graft-poly-(2-methacryloyloxyethyl) trimethyl ammonium chloride (KGM-g-PDMC) was prepared by using ceric ammonium nitrate as the initiator in aqueous solution. Negatively charged copper nanoclusters (CuNCs) were prepared by a one-step reduction method using glutathione as the reductant. Then, the two precursors mentioned above were combined through electrostatic attraction to form a conjugate (KGM-g-PDMC/CuNCs) exhibiting aggregation-induced emission (AIE). The resultant products were characterized by Fourier transform infrared spectroscopy, zeta potential and particle size analysis, X-ray photoelectron spectrometry, transmission electron microscopy, and fluorescence spectrophotometry. The results showed that KGM-g-PDMC enhanced the AIE effect of CuNCs, with an approximate 4-fold increase in fluorescence intensity. A cytotoxicity analysis showed that the products possess good biocompatibility. Moreover, cell imaging indicated that the products have potential for application in the field of biomedicine.

Positively charged ultrafiltration membranes fabricated via graft polymerization combined with crosslinking and branching for textile wastewater treatment

2-methacryloyloxy ethyl trimethylammonium chloride (DMC) was successfully grafted with 2-hydroxyethyl methacrylate (HEMA) as branching agent and N, N'-methylenebisacrylamide (MBAA) as crosslinker onto the surface of hydrolyzed polyacrylonitrile (HPAN) ultrafiltration membrane with high density via ceric ion (Ce4+)-induced graft polymerization. The successful graft polymerizations were confirmed by characterization of attenuated total reflectance spectrophotometer, X-ray photoelectron spectroscopy, scanning electron microscope and atomic-force microscopy. The obtained membranes showed surface positive charges and favorable hydrophilicity, which resulted in an ultrahigh permeability, distinguished rejection for positively charged dyes (>99%) and almost no retention for divalent salts (<4%), as well as excellent stability in multiple cycles of filtration. This work provided an efficient and facile approach to tailor the structure and properties of ultrafiltration membranes.

Cationic starch: an effective flocculant for separating algal biomass from wastewater RO concentrate treated by microalgae

Microalgae can remove nutrients and organic contaminants from municipal wastewater reverse osmosis concentrate (ROC) and enable resource recovery via biomass production. Two cationic starch flocculants (starch-graft-poly cationic moiety 2-methacryloyloxyethyl trimethyl ammonium chloride (St-g-PDMC) and starch-graft-poly cationic moiety 2,3-epoxypropyl trimethyl ammonium chloride (St-GTA)) were synthesized and tested as potential greener and lower cost alternatives to conventional chemical flocculants for harvesting Chlorella vulgaris and Nannochloropsis salina from the algae-treated ROC. St-GTA achieved up to 97% separation (based on optical density) for both algal species at the dosage of 5–10 mg g−1 dry cell weight (DWC) compared to alum (69% at 10 mg g−1 DWC) and PolyDADMAC (93% at 35 mg g−1 DWC). The overall better performance of St-GTA was attributed to its higher intrinsic viscosity, positive surface charge, and solubility. The harvesting efficiency was influenced by algal growth phases, which led to differences in the levels of negative charge and functional groups on the algal surfaces. The effectiveness of the flocculants was primarily associated with their respective level of positive surface charge (R2 = 0.87) that facilitated charge neutralization as indicated by apparent surface charge of the algal flocs (R2 = 0.97). Flocculation using St-GTA removed 40% TP, 25% TN, and 20% DOC from the residual contaminants of the algae-treated ROC. Overall, the study indicated that cationic starch could be an environmentally benign and cost-effective approach for harvesting microalgae from the treated ROC, and beneficial to the subsequent utilization of the harvested biomass.

Cationically functionalized dextrin polymer as an efficient flocculant for harvesting microalgae

The present study sets out to the development of cationic graft copolymer, dextrin -g-PMETAC through grafting of 2-methacryloyloxyethyl trimethyl ammonium chloride (METAC) on to the dextrin polymer. Flocculation efficiency of this graft cationic copolymer was studied towards the biomass harvesting efficiency of three indigenous microalgal strains viz, Scenedesmus sp. CBIIT(ISM), Micractinium sp. NCS2 and Chlorella sp. NCQ. The results demonstrated that the synthesized copolymer was very effective in microalgal dewatering. The biomass harvesting efficiency of the dextrin-g-PMETAC for Scenedesmus sp. CBIIT(ISM), Micractinium sp. NCS2 and Chlorella sp. NCQ was 98.87 ± 0.17 %, 98.19 ± 0.22 % and 97.56 ± 0.28 % at optimized dosage of flocculant 25 ppm 35 ppm and 45 ppm respectively. Comparative study of biomass composition of polymer induced flocculated biomass and centrifuged biomass in terms of proteins, carbohydrates, lipids, and residual ash content indicated that the biomass harvesting through dextrin-g-PMETAC does not affect the characteristics of microalgal biomass. Based on the obtained results, dextrin-g-PMETAC could be considered as an efficient polymeric flocculant towards the harvesting of microalgae.

Rheological Behavior of a Quaternary Ammonium Copolymer in the Presence of Inorganic Salts

Quaternary ammonium random copolymers poly(methacryloyloxyethyl trimethyl ammonium chloride-co-acrylamide) P(DMC-AM) with either varied cationicities or intrinsic viscosities were synthesized and their structure was analyzed by FTIR and NMR; the results verified the structure of the P(DMC-AM). The rheological behavior of the P(DMC-AM) resulting from its polymer structure (cationicity and intrinsic viscosity) in NaCl aqueous solutions was studied. The results showed that increasing the polymer cationicity could enhance its salt resistance, especially at low cationicity, and the apparent viscosity was in direct proportion to the intrinsic viscosity of the P(DMC-AM) in salt solutions. Furthermore, salt effects (ionic radius, cationic valence, and anion valence) on the apparent viscosity were characterized. They clearly showed that the apparent viscosity was decreased with the increase of ion radius and ion valence. In particular, a difference in polymer aggregation was found when multivalent cations or anions containing solvents were added; two schematic models describing the rheological behavior of the P(DMC-AM) molecules in multivalent salt solutions are proposed.

Functional cellulose nanocrystals containing cationic and thermo-responsive polymer brushes

Cationic and thermo-responsive polymer brushes were grafted from the surface of cellulose nanocrystals. Di(ethylene glycol) methyl ether methacrylate (MEO2MA) and poly(oligoethylene glycol) methyl ether acrylate (OEGMA300) and (2-methacryloyloxyethyl) trimethylammonium chloride (DMC) were grafted from cellulose nanocrystals (CNCs) via free radical polymerization. The CNC-g-POEGMA (CP) possessed a tunable lower critical solution temperature (LCST) of about 50 °C, and cloud point measurements confirmed that the LCST of the nanoparticles could be manipulated within the range of 40−47 °C by adjusting the DMC content. The salt effect was also investigated, and the results revealed a typical salting-out effect for the CNC-g-POEGMA after the introduction of KCl. On the other hand, the CNC-g-POEGMA-g-DMC (CPD) copolymers displayed two salt-responsive characteristics; polyelectrolyte effect at lower salt concentrations, followed by the salting-out effect at higher salt concentrations, which is dependent on the DMC content.

Combination of two antithrombogenic methodologies for preventing thrombus formation on a poly(ether ether ketone) substrate

To enhance the total antithrombogenicity of poly(ether ether ketone) (PEEK), we examined a combination of two methodologies for the suppression of activation in both the platelet and coagulation systems. A random copolymer (PMT) composed of a zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) unit and a cationic 2-methacryloyloxyethyl trimethylammonium chloride (TMAEMA) unit was grafted onto the PEEK surface by photoinduced self-initiated graft polymerization of the PEEK substrate (PMTx-g-PEEK). Then, negatively charged heparin was immobilized by ionic binding with TMAEMA units (Hep/PMTx-g-PEEK). The TMAEMA unit composition on grafted PMT altered the surface ζ-potentials of the PEEK substrates. Amounts of immobilized heparin depended on the ζ-potential. The concentration of heparin became constant on the sample surface where the TMAEMA unit composition was 30% or more, and was approximately 2.0 μg/cm2. The Hep/PMTx-g-PEEK with a TMAEMA unit composition of 50% showed not only decreased platelet adhesion, but also a 4-fold extension of the blood coagulation time of the poly(MPC)-g-PEEK substrate. The poly(MPC) layer could inhibit platelet adhesion and activation, resulting in surface antithrombogenic properties. Additionally, heparin released from the Hep/PMTx-g-PEEK prevented activation of the coagulation system in whole blood. Therefore, the combination of these antithrombogenic methodologies was promising for prolonging the blood coagulation period of the materials.