Subsequent Quaternization Research Articles

Thermally Cross-Linked Anion Exchange Membranes from Solvent Processable Isoprene Containing Ionomers

Random copolymers of isoprene and 4-vinylbenzyl chloride (VBCl) with varying compositions were synthesized via nitroxide-mediated polymerization. Subsequent quaternization afforded solvent processable and cross-linkable ionomers with a wide range of ion exchange capacities (IECs). Solution cast membranes were thermally cross-linked to form anion exchange membranes. Cross-linking was achieved by taking advantage of the unsaturations on the polyisoprene backbone, without added cross-linkers. A strong correlation was found between water uptake and ion conductivity of the membranes: conductivities of the membranes with IECs beyond a critical value were found to be constant related to their high water absorption. Environmentally controlled small-angle X-ray scattering experiments revealed a correlation between the average distance between ionic clusters and the ion conductivity, indicating that a well-connected network of ion clusters is necessary for efficient ion conduction and high ion conductivity.

Reversible sol-gel transitions of aqueous dispersions of silica nanoparticles grafted with diblock copolymer brushes composed of a thermosensitive inner block and a charged outer block.

We report in this article that aqueous dispersions of thermosensitive diblock copolymer brush-grafted 17 nm silica nanoparticles (hairy NPs) can undergo in situ, reversible sol-gel transitions in response to temperature changes. The brushes consisted of a thermosensitive poly(methoxydi(ethylene glycol) methacrylate) (PDEGMMA) inner block and a charge-carrying, poly(DEGMMA-co-2-(methacryloyloxy)ethyltrimethylammonium iodide) outer block, which were prepared by a one-pot, surface-initiated atom transfer radical polymerization and subsequent quaternization of tertiary amine moieties in the second block with iodomethane. Above a critical concentration, the aqueous dispersion of hairy NPs with an appropriate block copolymer composition exhibited a reversible transition from a free flowing liquid to a free standing hydrogel upon cooling from elevated temperatures, which was driven by the lower critical solution temperature transition of the thermosensitive inner block of hairy NPs as confirmed by dynamic light scattering study. At the same concentration of hairy NPs, the sol-gel transition temperature was higher when the highly hydrated, charged outer block was longer. The transition temperature decreased with decreasing the concentration of hairy NPs in the dispersion; reversible gelation was achieved with a concentration of hairy NPs in water as low as 5.5 wt%. Interestingly, the LCST transition of the inner thermosensitive PDEGMMA block disappeared and no sol-gel transition was observed in the studied temperature range when the charged outer block was sufficiently long.

Синтез, антимикробная и протистоцидная активность гидрохлоридов 3-арилоксиэтил(бензил)-1- карбомоилметил-2-иминобензимидазолинов

Алкилированием 2-аминобензимидазола метилиодидом, а также бензил- или 2-арилоксиэтилбромидами получены 1-замещенные 2-аминобензимидазолы, которые при кватернизации хлорацетамидом образуют не описанные ранее гидрохлориды 3-арилоксиэтил(бензил)-1-карбомоилметил-2-иминобензимидазолинов. Показано, что эти соединения обладают антибактериальной активностью в отношении некоторых патогенных грамположительных и грамотрицательных микробов (Staphylococcus aureus, Escherichia coli), сочетающейся с выраженным на уровне клинически используемых препаратов сравнения протистоцидным действием на простейшие виды Colpoda steinii.

Synthesis of Rice Bran Fatty Acids (RBFAs) Based Cationic Surfactants and Evaluation of Their Performance Properties in Combination with Nonionic Surfactant

Abstract Cationic surfactants are mainly used for fabric softening in laundry applications. Esterquats are one class of cationic surfactants and are superseding other existing cationic surfactants on account of their excellent biodegradability. However, indigenous and cost-effective production of esterquats poses new challenges for the researchers. The availability of rice bran fatty acids and its price structure in Indian scenario makes this fatty feedstock quite lucrative for cost-effective synthesis of cationic surfactants. In the present study, esterquats based on rice bran fatty acids (RBFAs) were synthesized by using different alkanolamines i. e. diethanolamine (DEA) and triethanolamine (TEA) and dimethyl sulphate (DMS) for obtaining cationic surfactants which was used as active softener ingredient. For this purpose, esterquats have been synthesized by esterification of RBFAs and alkanolamines to recover diesters followed by the subsequent quaternization of diesters by DMS. It was found that the optimum reaction conditions for esterification of RBFAs and DEA was 140 °C and 3 h of duration. However, for RBFAs and TEA, it was found to be 140 °C and 4 h of duration. The chemical structures of diesters and esterquats were confirmed by FT-IR and NMR spectra. Studies of surface active and performance properties of these surfactants showed that esterquats based on TEA had better surface active and performance properties as compared to DEA based esterquats. The synthesized cationic surfactants when mixed with nonionic surfactant showed better performance properties as compared to the nonionic surfactant alone.

Hybrid anion-exchange membranes derived from quaternized polysulfone and functionalized titanium dioxide

Polysulfone is modified via chloromethylation and TiO2 is functionalized by three modification reagents (anionic surfactant, 1,3-propane sultone and Dopamine). Based them, a series of promising organic-inorganic hybrid membranes for anion-exchange membrane fuel cells have been prepared by incorporating functionalized TiO2 submicrospheres into the chloromethylated polysulfone, subsequent quaternization and alkalization. The chloromethylation process is confirmed by Nuclear magnetic resonancespectra. The functionalization of TiO2 is proved through Fourier transform infrared spectroscopy and Thermogravimetric analysis. The quaternization is testified by contact angle measurement. Associated characteristics of the hybrid membranes were investigated, including water uptake, swelling behavior, mechanical property and ion conductivity. Compared with other anion-exchange membranes, the hybrid membranes containing 5% TiO2 with –SO3H groups exhibits higher ionic conductivity because of the acid-base ionic interactions between the inorganic filler and polymer chains. It demonstrates an ionic conductivity of 3.13×10−2 S/cm and an acceptable alkaline solution stability at 60°C.

Acrylate copolymers containing benzimidazolium moieties: synthesis and antimicrobial applications

AbstractThe allylic monomer N-allyl-N-butylbenzimidazolium bromide (ABBB) was synthesized by reacting allyl bromide with benzimidazole and subsequent quaternization with 1-bromobutane. Copolymers of ABBB with butyl acrylate (BA) were prepared in dimethyl formamide solution at 70°C using a free-radical polymerization technique with different monomer feed ratios. Monomer reactivity ratios for the ABBB-BA pairs were evaluated by the Fineman-Ross (r1=0.40; r2=1.49) and Kelen-Tüdõs (r1=0.36; r2=1.46) linearization methods. Thermal behavior of the copolymers of different compositions was evaluated by thermogravimetric analysis. The copolymers were tested for antimicrobial properties against selected strains of bacteria and fungi and were found to be active against the strains. The growth-inhibitory effect of the copolymers varied according to the composition of the polymer: the effect increased with increasing content of the substituted benzimidazolium group in the polymer chain.

New biscyanine dye based on 1-{2-oxo-2-[4-(2-oxo-2H-chromen-3-yl)phenyl]ethyl}-4-methylpyridinium bromide. Electron transitions and electronic spectra

New biscyanine dye, 4-{2-[4-(dimethylamino)phenyl]ethenyl}-1-{2-[4-(dimethylamino)phenyl]-1-[4-(2-oxo-2H-chromen-3-yl)benzoyl]ethenyl}pyridinium bromide, has been prepared via condensation of 4-dimethylaminobenzaldehyde with 4-methyl-1-{2-oxo-2-[4-(2-oxo-2H-chromen-3-yl)phenyl]ethyl}pyridinium bromide. The latter has been synthesized via the Meerwein reaction of coumarin with 4-acetylphenyldiazonium chloride with subsequent bromination and quaternization of the formed α-bromoketone under the action of 4-methylpyridine. Electronic spectra are analyzed, and quantum-chemical simulation of possible isomers of the biscyanine dye has been performed.

Cationic polymer brush-modified cellulose nanocrystals for high-affinity virus binding.

Surfaces capable of high-affinity binding of biomolecules are required in several biotechnological applications, such as purification, transfection, and sensing. Therein, the rod-shaped, colloidal cellulose nanocrystals (CNCs) are appealing due to their large surface area available for functionalization. In order to exploit electrostatic binding, their intrinsically anionic surfaces have to be cationized as biological supramolecules are predominantly anionic. Here we present a facile way to prepare cationic CNCs by surface-initiated atom-transfer radical polymerization of poly(N,N-dimethylaminoethyl methacrylate) and subsequent quaternization of the polymer pendant amino groups. The cationic polymer brush-modified CNCs maintained excellent dispersibility and colloidal stability in water and showed a ζ-potential of +38 mV. Dynamic light scattering and electron microscopy showed that the modified CNCs electrostatically bind cowpea chlorotic mottle virus and norovirus-like particles with high affinity. Addition of only a few weight percent of the modified CNCs in water dispersions sufficed to fully bind the virus capsids to form micrometer-sized assemblies. This enabled the concentration and extraction of the virus particles from solution by low-speed centrifugation. These results show the feasibility of the modified CNCs in virus binding and concentrating, and pave the way for their use as transduction enhancers for viral delivery applications.

Radical crossover reactions of a dynamic covalent polymer brush for reversible hydrophilicity control

Reversible hydrophilicity control of a radically exchangeable polymer brush with dynamic covalent linkages was successfully demonstrated. A polymer brush with alkoxyamine units was prepared via surface-initiated atom transfer radical polymerization, and reversible surface hydrophilicity control was achieved via dynamic covalent exchange reactions of alkoxyamines. Exchange reactions between alkoxyamine units in the side chains of the polymer brush and the terminal of poly(4-vinylpyridine) (P4VP) were carried out in order to prepare a side-chain functionalized polymer brush. Subsequent quaternization of P4VP chains with iodomethane was carried out to prepare a more hydrophilic surface. In addition, a de-grafting reaction of the quaternized P4VP side chains was performed to confirm reversibility of the alkoxyamine via radical exchange reactions on the surface. All the composition and wettability changes were investigated via X-ray photoelectron spectroscopy and contact angle measurements.

Syntheses and aggregation behavior of pyridine-based CH–CF hybrid surfactants

Five cationic CH–CF hybrid surfactants, each of which has a hydrocarbon chain (CnH2n+1, n=8, 10, 12, 14, 16) and a fluorocarbon one (C6F13), have been synthesized. Taking the advantage of the Grignard reaction and the subsequent quaternization, the hybrid surfactants were obtained with high synthetic yields over 65%. Their structures have been unambiguously confirmed by FTIR, 1H NMR, 19F NMR, 13C NMR and MS measurements. 19F NMR revealed that the presence of the chiral carbon center induced a nonequivalent magnetic resonance of the adjacent fluorine nuclei. The aggregation behavior of the hybrid surfactants were investigated by surface tension, conductivity and steady-state fluorescence measurements. Surface tension measurements revealed that the hybrid surfactants exhibited high surface activity. With increasing hydrocarbon chain length, the critical micellar concentration (cmc) decreased while the surface tension at the cmc (γcmc) increased. Both the results of conductivity and surface tension measurements showed there exists a stepwise aggregation behavior for the hybrid surfactants with n=8 and 10. Steady-state fluorescence measurements showed fairly good agreement with the results obtained from conductivity and surface tension measurements. Evaluation of the thermodynamic parameters (ΔGm0, ΔHm0, ΔSm0) showed that the aggregate formation of the hybrid surfactants with n<16 is enthalpy-driven at low temperature, which turns to entropy-driven at high temperature. While the aggregate formation of the hybrid surfactant with n=16 is entropy-driven within all the investigated temperature ranges.

An imidazolium-based polymerized ionic liquid via novel synthetic strategy as polymer electrolytes for lithium ion batteries

An imidazolium-based polymerized ionic liquid (PIL), poly(1-ethyl-3-vinylimidazolium bis(trifluoromethanesulfonylimide)) is successfully synthesized via a new three-step process comprising the direct radical polymerization of the 1-vinylimidazole monomer, and subsequent quaternization reaction followed by an anion exchange procedure. Furthermore, polymer electrolytes are prepared by blending as-obtained PIL as the polymer host with an ionic liquid and LiTFSI salt. Electrochemical measurements demonstrate that compared with polymer electrolytes containing the PIL host synthesized by the conventional route, polymer electrolytes containing the PIL host obtained by new synthetic process exhibit significantly improved capacity and cycling performance, which is due to higher ionic liquid content.

Galactose‐Functionalized Cationic Polycarbonate Diblock Copolymer for Targeted Gene Delivery to Hepatocytes

To mediate selective gene delivery to hepatocytes via the asialoglycoprotein receptors (ASGP-Rs), we designed and synthesized well-defined and narrowly dispersed galactose- and glucose-functionalized cationic polycarbonate diblock copolymers (designated as Gal-APC and Glu-APC, respectively) using organocatalytic ring-opening polymerization of functionalized carbonate monomers, with a subsequent quaternization step using bis-tertiary amines to confer quaternary and tertiary amines for DNA binding and endosomal buffering, respectively. The sugar-functionalized diblock copolymers effectively bound and condensed DNA to form positively charged nanoparticles (<100 nm in diameter and ≈30 mV zeta-potential) that were stable under high physiological salt conditions. In comparison to the control Glu-APC/DNA complexes, Gal-APC/DNA complexes mediated significantly higher gene expression in ASGP-R positive HepG2 cells with no significant difference observed in ASGP-R negative HeLa cells. The co-incubation of Gal-APC/DNA complexes with a natural ASGP-R ligand effectively led to a decrease in gene expression, hence providing evidence for the ASGP-R mediated endocytosis of the polyplexes. Importantly, the Gal-APC/DNA complexes induced minimal cytotoxicities in HepG2 cells at the N/P ratios tested. Taken together, the galactose-functionalized cationic polycarbonate diblock copolymer has potential for use as a non-viral gene vector for the targeted delivery of therapeutic genes to hepatocytes in the treatment of liver diseases.

Quaternized and sulfated xylan derivative films

Xylan quaternized sulfate films were prepared from beech xylan (X) and compared with fully sulfated xylan films (XS). When quaternized xylan (QX) was prepared in the first step (DSQ=0.55), than by sulfation of QX in the second step the fully substituted ampholytic derivative (QXS; DSQ=0.33; DSS=1.67) could be obtained. By sulfation in first step, xylan sulphate (SX, DSS=0.70) was obtained and by subsequent quaternization, SXQ film with DSQ=0.55 and DSS=0.33 which contained partially unsubstituted hydroxyls. The molar masses (Mn) of the film's soluble parts were increasing in order X<SX<SXQ<QX<XS<QXS. In all films there were some insoluble particles present as determined by the amount of recovered masses by SEC-MALS. The materials were further characterized by AFM, XRD, TG/DTG/DTA, NMR and mechanical testing. QXS and SXQ could form mechanically more stable films than XS specimens.

Counter‐Anion Effect on the Properties of Anion‐Conducting Polymer Electrolyte Membranes Prepared by Radiation‐Induced Graft Polymerization

AbstractGraft‐type anion‐conducting polymer electrolyte membranes (AEMs) are prepared by the radiation‐induced graft polymerization of chloromethylstyrene into poly(ethylene‐co‐tetrafluoroethylene) (ETFE) films and subsequent quaternization with trimethylamine. AEMs in the hydroxide form (AEM‐OH) are prepared by immersing the chloride form (AEM‐Cl) in 1 M potassium hydroxide (KOH) solution, followed by KOH and washing with nitrogen‐saturated water to prevent bicarbonate formation (AEM‐HCO3). The AEM‐OH shows conductivity and water uptake four and two times higher than AEM‐Cl and ‐HCO3 and is thermally and chemically less stable, resulting in the tendency to absorb water and to convert to the bicarbonate form.magnified image

Self-reinforced endocytoses of smart polypeptide nanogels for “on-demand” drug delivery

The pH and reduction dual-responsive polypeptide nanogels with self-reinforced endocytoses were prepared through ring-opening polymerization of l-glutamate N-carboxyanhydrides, deprotection of benzyl group and subsequent quaternization reaction between γ-2-chloroethyl-l-glutamate unit in polypeptide block and 2,2′-dithiobis(N,N-dimethylethylamine). The nanogels were revealed to exhibit smart pH and reduction dual-responsiveness, and excellent biocompatibilities, which expressed great potential as antitumor drug nanocarriers. Doxorubicin (DOX) as a model antitumor drug was loaded into nanogels through dispersion. DOX-loaded nanogels displayed a stable core-cross-linked structure under normal physiological condition (pH7.4), while rapidly releasing the payloads in the mimicking endosomal (pH5.3), tumor tissular (pH6.8) or intracellular reductive microenvironments (10.0mM glutathione). Confocal fluorescence microscopy demonstrated that DOX-loaded nanogels could deliver DOX into HepG2 cells (a human hepatoma cell line) more efficiently than the parent DOX-loaded micelle and free DOX. The enhanced cellular internalizations of DOX-loaded nanogels were more significant under tumor tissular acidic condition (pH6.8) ascribed to the quaternary ammonium groups in the cores. In addition, DOX-loaded nanogels exhibited improved in vitro and in vivo antitumor activities, and in vivo securities compared with DOX-loaded micelle and free DOX. These excellent features of the smart nanogels with quaternary ammonium groups were endowed with a bright prospect for intracellular targeting antitumor drug delivery.

Smart secondary polyurethane dispersions

Secondary dispersions of cationic segmented polyurethanes (PUs) with thermoresponsivity (upper critical solution temperature (UCST) in water), high solid contents and antibacterial properties are highlighted in this paper. PUs were prepared by polyaddition reactions and subsequent quaternization with methyl iodide. No additional stabilizers, organic solvents or special procedures were required to obtain stable aqueous dispersions containing up to 10 wt% PU; in contrast, stable dispersions were straightforwardly accessed by a combination of UCST behavior and repulsive electrostatic forces among the positively charged segments, which meets the requirements of a green chemistry process. Particle size and UCST strongly depended on the solid content of the dispersions and the content of poly(ethylene glycol) segments in the copolymers. The dispersions exhibited fast-acting antibacterial properties against Escherichia coli. © 2013 Society of Chemical Industry

Thermoset Magnetic Materials Based on Poly(ionic liquid)s Block Copolymers

A new methodology for the preparation of nanostructured magnetic thermoset materials without any kind of metal oxide or metal magnetic nanoparticles has been proposed. The present study focuses on the nanostructuration of thermoset materials based on poly(ionic liquid)s block copolymer and the subsequent production of magnetic nanostructured thermoset. Judicious selection of block copolymer, such as P2VP-b-PMMA, soluble in epoxy and its subsequent quaternization leads to a phase modification of the system, from totally soluble to a nanostructured system. Different degree of quaternization of the pyridine groups showed the range of quaternization values which allowed the nanostructuration of the thermoset. Magnetic material was obtained by anion exchange of the quaternized poly(ionic liquid) block copolymer without using any kind of metal oxide or metal magnetic nanoparticles. The different materials obtained by quaternization of the block copolymers, the anion exchange of the polymeric ionic liquid and th...

Light‐Switchable Polymer from Cationic to Zwitterionic Form: Synthesis, Characterization, and Interactions with DNA and Bacterial Cells

A novel cationic polymer poly(N,N-dimethyl-N-[3-(methacroylamino) propyl]-N-[2-[(2-nitrophenyl)methoxy]-2-oxo-ethyl]ammonium chloride) is synthesized by free-radical polymerization of N-[3-(dimethylamino)propyl] methacrylamide and subsequent quaternization with o-nitrobenzyl 2-chloroacetate. The photolabile o-nitrobenzyl carboxymethyl pendant moiety is transformed to the zwitterionic carboxybetaine form upon the irradiation at 365 nm. This feature is used to condense and, upon the light irradiation, to release double-strand DNA tested by gel electrophoresis and surface plasmon resonance experiments as well as to switch the antibacterial activity to non-toxic character demonstrated for Escherichia coli bacterial cells in solution and at the surface using the self-assembled monolayers.

PH and reduction dual-responsive nanogel cross-linked by quaternization reaction for enhanced cellular internalization and intracellular drug delivery

A novel pH and reduction dual-responsive nanogel with improved cellular internalization was prepared through atom transfer radical polymerization and subsequent quaternization reaction. Doxorubicin (DOX), a model anticancer drug, was loaded into the nanogel via dispersion. The DOX-loaded nanogel presented a stable core-cross-linked structure under physiological conditions, but quickly released its payload in an acidic (pH 6.8) and reductive (10.0 mM glutathione) environment. Confocal fluorescence microscopy and fluorescence flow cytometry revealed that the DOX-loaded nanogel could deliver DOX into the cytoplasm and nucleus of cells, more efficiently than that of free DOX. The improved cellular internalization was more significant under acidic and reductive conditions, which was analogous to the pH and reductive conditions in endosomes and cytoplasm. In vitro cytotoxicity studies demonstrated that the pH and reduction responsive DOX-loaded nanogel could inhibit cellular proliferation more efficiently than free DOX. This dual-bioresponsive nanogel with quaternary ammonium salt group has appeared to be highly promising in the further development of intracellular drug transporters.

Alkylation of 1,2,3-benzotriazole with iodomethyl ketones

Solvent-free reactions of 1,2,3-benzotriazole with 1-iodopropan-2-one and 1,3-diiodopropan-2-one in the absence of a catalyst involved alkylation of the heteroring at the N1 atom and subsequent quaternization at the N3 atom with formation of 1,3-bis(2-oxopropyl)-1H-1,2,3-benzotriazolium triiodide which is a new conducting ionic liquid. The reaction of 1,2,3-benzotriazole with 1,3-diiodopropan-2-one was accompanied by reductive deiodination of the iodomethyl groups in the initial ketone with hydrogen iodide liberated by N1-alkylation. Triiodide ion readily exchanges for nitrate ion by the action of AgNO3 to produce 1,3-bis(2-oxopropyl)-1H-1,2,3-benzotriazolium nitrate. The reaction of 1,2,3-benzotriazole with 2-iodo-1-phenylethan-1-one in melt resulted in the formation of 1,3-bis(2-oxo-2-phenylethyl)-1H-1,2,3-benzotriazolium triiodide.