Search Results (35)

Zwitterionic polymers have garnered significant attention for their distinctive properties, such as biocompatibility, antifouling capabilities, and resistance to protein adsorption, making them promising candidates for a wide range of applications, including drug delivery, oil production inhibitors, and water purification membranes. This study reports the synthesis and characterization of zwitterionic monomers and polymers through the modification of linear, vinyl, and aromatic heterocyclic functional groups via reaction with 1,3-propanesultone. Four zwitterionic polymers with varying molecular structures—ranging from linear to five and six membered ring systems—were synthesized: poly(sulfobetaine methacrylamide) (pSBMAm), poly(sulfobetaine-1-vinylimidazole) (pSB1VI), poly(sulfobetaine-2-vinylpyridine) (pSB2VP), and poly(sulfobetaine-4-vinylpyridine) (pSB4VP). Their molecular weights, thermal behavior, and self-assembly properties were analyzed using gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and zeta potential measurements. The glass transition temperatures (Tg) ranged from 276.52 °C for pSBMAm to 313.69 °C for pSB4VP, while decomposition temperatures exhibited a similar trend, with pSBMAm degrading at 301.03 °C and pSB4VP at 387.14 °C. The polymers’ self-assembly behavior was strongly dependent on pH and their surface charge, particularly under varying pH conditions: spherical micelles were observed at neutral pH, while fractal aggregates formed at basic pH. These results demonstrate that precise modifications of the chemical structure, specifically in the linear, imidazole, and pyridine moieties, enable fine control over the thermal properties and self-assembly behavior of polyzwitterions. Such insights are essential for tailoring polymer properties for targeted applications in filtration membranes, drug delivery systems, and solid polymer electrolytes, where thermal stability and self-assembly play crucial roles. Full article

Wellbore instability caused by hydration during the development of shale gas reservoirs poses significant challenges to drilling engineering. In this study, a novel and environmentally friendly shale inhibitor, TIL-NH₂, was synthesized via free radical polymerization using 1-vinylimidazole and N-(2-bromoethyl)-1,3-propanediamine dihydrobromide as the main raw materials. The molecular structure of TIL-NH₂ was characterized by infrared spectroscopy and nuclear magnetic resonance. Incorporating imidazole cations and amino bifunctional groups, TIL-NH₂ exhibits excellent inhibitory performance and environmental friendliness. Its performance was systematically evaluated through linear swelling tests, shale cuttings rolling recovery tests, permeability recovery experiments, and dynamic adsorption analyses. The results indicate the following: (1) At a concentration of 1.2 wt%, TIL-NH₂ reduced the linear swelling height of shale by 65.69%, significantly outperforming traditional inhibitors like KCl and NW-1. (2) Under conditions of 140 °C, the cuttings rolling recovery rate of TIL-NH₂ reached 88.12%, demonstrating excellent high-temperature resistance. (3) Permeability recovery experiments showed that at a concentration of 2.0 wt%, TIL-NH₂ achieved a permeability recovery rate of 90.58%, effectively mitigating formation damage. (4) Dynamic adsorption experiments indicated that at a concentration of 2.5 wt%, the adsorption capacity tended toward saturation, reaching 26.00 mg/g, demonstrating stable adsorption capability. Additionally, environmental friendliness evaluations revealed that TIL-NH₂ has a degradation rate exceeding 90% within 28 days, and its acute toxicity is significantly lower than that of traditional inhibitors like KCl (the LC₅₀ of TIL-NH₂ is 1080.3 mg/L, whereas KCl is only 385.4 mg/L). This research provides a high-efficiency and environmentally friendly new inhibitor for green drilling fluid systems in horizontal shale gas wells, offering important references for technological advancements in unconventional energy development. Full article

In cold methanol, energetic ionic liquid 1-n-propyl-3-vinyl-imidazol-1-ium perchlorate, 1, crystallizes in the presence of excess Ba(ClO₄)₂, 2, into tetrakis 1-propyl-3-vinyl-imidazol-1-ium·barium hexa-perchlorate, 3. Crystals of 3, with molecular formula (C₈H₁₃N₂)₄·BaCl₆O₂₄, are colorless and monoclinic, with space group P2₁/c. The crystal structure is characterized by a dodecahedral coordination around the barium atom, with each perchlorate chelating Ba²⁺ in a κ²O,O’ fashion, and the Ba(ClO₄)₆⁴⁻ anion is surrounded by four imidazolium cations. Full article

Cotton fiber consumption is higher than any other natural fiber due to its superior mechanical and physical properties. In the conventional reactive dyeing process, the dye undergoes hydrolysis due to hydrogen bonding and weak Van der Waals forces, yielding poor washing color fastness. Additionally, the post-dyeing wash-off process consumes significant amounts of water, energy, and time in order to remove the unreacted and hydrolyzed dye. Therefore, reactive dyes are predominantly utilized to color cotton fabrics as the covalent bond formed between dye and fiber results in excellent washing fastness for a wide range of colors, and improved ease of use. To support more efficient, economical, and sustainable reactive dyeing, polymers can be used as effective dye transfer inhibitors (DTIs) in the reactive wash-off process. In this study, poly(vinylpyrrolidone) (PVP) homopolymer and poly(vinylpyrrolidone)-co-poly(vinylimidazole) (PVP-co-PVI) were synthesized at different molecular weights. These polymers were then employed as DTIs to evaluate their performance during the wash-off process for dyed cotton fabrics treated with three reactive dyes (Reactive Red 195, Reactive Blue 221, and Reactive Yellow 145). It is noteworthy to mention that the alternative wash-off procedure involved only three stages, in contrast to the series of washing steps necessary in the conventional method. Evaluation of the DTIs was focused on parameters such as color strength, washing fastness, chemical oxygen demand (COD), as well as energy, water, and time consumption. The findings revealed that while the polymer DTIs generated minor differences in dyed fabric colors in comparison to conventional dyeing, they significantly improved washing fastness. The polymer DTIs studied display excellent potential to provide a much more sustainable dyeing process by saving 90% energy, 40% water, and 50% time versus conventional wash-off processing. The wastewater COD values from the polymer-assisted reactive dye wash-off process were higher for all reactive dyes tested than those from conventional processing. While the higher COD values are attributed to the lower water volumes, this finding highlights the need for further studies. In summary, PVP polymers successfully served as DTIs in the reactive dyeing washing-off process, providing massive water-energy-time efficiency improvements and, subsequently, a more sustainable process for cotton fabric dyeing. Full article

Carboxymethyl cellulose sodium salt is a common water-soluble derivative of cellulose. It serves as a bioinert mucoadhesive material extensively used in biomedicine, particularly for crafting targeted drug delivery systems. In our study, we demonstrate that graft copolymers of sodium carboxymethyl-cellulose with poly(N-vinylimidazole) can function as carriers for the antibacterial drug metronidazole. Non-covalent associations form between the components, excluding the involvement of the nitro groups of the drug in the interaction. These loaded copolymers exhibit the capability to release the drug under conditions mimicking the stomach environment for up to 48 h. This renders the obtained associations promising candidates for the development of a metronidazole-targeted delivery system. Full article

In this work, we present the modification of a medical-grade silicone catheter with the N-vinylimidazole monomer using the grafting-from method at room temperature and induced by gamma rays. The catheters were modified by varying the monomer concentration (20–100 vol%) and the irradiation dose (20–100 kGy). Unlike the pristine material, the grafted poly(N-vinylimidazole) chains provided the catheter with hydrophilicity and pH response. This change allowed for the functionalization of the catheters to endow it with antimicrobial features. Thus, the quaternization of amines with iodomethane and bromoethane was performed, as well as the immobilization of silver and ampicillin. The inhibitory capacity of these materials, functionalized with antimicrobial agents, was challenged against Escherichia coli and Staphylococcus aureus strains, showing variable results, where loaded ampicillin was amply better at eliminating bacteria. Full article

In the course of studying Diels–Alder reactions of 4-vinylimidazoles with N-phenylmaleimide, it was discovered that they engage in cycloaddition at room temperature to give high yields of the initial cycloadduct as a single stereoisomer. In certain cases, the product precipitated out of the reaction mixture and could be isolated by simple filtration, thereby avoiding issues with aromatization observed during chromatographic purification. Given these results, intramolecular variants using doubly activated dienophiles were also investigated at room temperature. Amides underwent cycloaddition at room temperature in modest yields, but the initial adducts were not isolable with N_imid-benzyl-protected systems. Attempts to extend these results to the corresponding esters and hydroxamate were less successful with these substrates only undergoing cycloaddition at elevated temperatures in lower yields. Density functional theory calculations were performed to evaluate the putative transition states for both the inter- and intramolecular variants to rationalize experimental observations. Full article

Polyoxometalates (POMs) exhibit unique structural characteristics and excellent physical and chemical properties, which have attracted significant attention from scholars in the fields of anticancer research and chemotherapy. Herein, we successfully synthesized and structurally characterized two novel polyoxovanadates (POVs), denoted as POVs-1 and POVs-2, where [M(1-vIM)₄]₂[V^V₄O₁₂]·H₂O (M: Ni^II and Mn^II, 1-vinylimidazole abbreviated as 1-vIM) serve as ligands. The two POVs are isomeric and consist of fundamental structural units, each comprising one [V₄O₁₂]⁴⁻ cluster, two [M(1-vIM)₄]²⁺ cations, and one water molecule. Subsequently, we evaluated the cell viability of human hepatocellular carcinoma (HepG-2) cells treated with the synthesized POVs using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazoliumbromide) assay. And the changes in cell nucleus morphology, mitochondrial membrane potential (Δψ_m), and reactive oxygen species levels in HepG-2 exposed to POVs were monitored using specific fluorescent staining techniques. Both hybrid POVs showed potent inhibitory activities, induing apoptosis in HepG-2 cells along with significant mitochondria dysfunction and a burst of reactive oxygen species. Notably, the inhibitory effects of POVs-2 were more pronounced than those of POVs-1, which is primarily attributed to the different transition metal ions present. These findings underscore the intricate relationship between the metal components, structural characteristics, and the observed antitumor activities in HepG-2 cells. Full article

This study investigates the features of interactions between cysteine proteases (bromelain, ficin, and papain) and a graft copolymer of carboxymethyl cellulose sodium salt with N-vinylimidazole. The objective is to understand the influence of this interactions on the proteolytic activity and stability of the enzymes. The enzymes were immobilized through complexation with the carrier. The interaction mechanism was examined using Fourier-transform infrared spectroscopy and flexible molecular docking simulations. The findings reveal that the enzymes interact with the functional groups of the carrier via amino acid residues, resulting in the formation of secondary structure elements and enzyme’s active sites. These interactions induce modulation of active site of the enzymes, leading to an enhancement in their proteolytic activity. Furthermore, the immobilized enzymes demonstrate superior stability compared to their native counterparts. Notably, during a 21-day incubation period, no protein release from the conjugates was observed. These results suggest that the complexation of the enzymes with the graft copolymer has the potential to improve their performance as biocatalysts, with applications in various fields such as biomedicine, pharmaceutics, and biotechnology. Full article

A composite proton conducting membrane (PCM) was prepared by radiation-induced grafting (RIG) of binary mixtures of 4-vinyl pyridine (4-VP) and 1-vinylimidazole (1-VIm) onto poly(ethylene-co-tetrafluoroethylene) (ETFE) film followed by phosphoric acid (PA) doping. The grafting parameters such as absorbed dose, temperature, monomer concentration, time, and monomer ratio were varied to control the degree of grafting (DG%). The effect of the reactivity ratio of 4-VP and 1-VIm on the composition and degree of monomer unit alternation in the formed graft copolymer was investigated. The changes in the chemical and physical properties endowed by grafting and subsequent PA acid doping were monitored using analytical instruments. The mechanical properties and proton conductivity of the obtained membrane were evaluated and its performance was tested in H₂/O₂ fuel cell at 120 °C under anhydrous and partially wet conditions. The acid doping level was affected by the treatment parameters and enhanced by increasing DG. The proton conductivity was boosted by incorporating the combination of pyridine and imidazole rings originating from the formed basic graft copolymer of 4-VP/1-VIm dominated by 4-VP units in the structure. The proton conductivity showed a strong dependence on the temperature. The membrane demonstrated superior properties compared to its counterpart obtained by grafting 4-VP alone. The membrane also showed a strong potential for application in proton exchange membrane fuel cells (PEMFC) operating at 120 °C. Full article

For the first time, double stimuli-responsive properties of poly(N-isopropylacrylamide) (PNIPA) and poly(1-vinylimidazole) (PVIM) block copolymers in aqueous solutions were studied. The synthesis of PNIPA₆₀-b-PVIM₉₀ and PNIPA₂₈-b-PVIM₆₂-b-PNIPA₂₉ was performed using reversible addition–fragmentation chain transfer (RAFT) polymerization. The polymers were characterized by size exclusion chromatography and ¹H NMR spectroscopy. The conformational behavior of the polymers was studied using dynamic light scattering (DLS) and fluorescence spectroscopy (FS). It was found that PNIPA and block copolymers conformation and ability for self-assembly in aqueous medium below and above cloud point temperature depend on the locus of hydrophobic groups derived from the RAFT agent within the chain. Additionally, the length of PVIM block, its locus in the chain and charge perform an important role in the stabilization of macromolecular micelles and aggregates below and above cloud point temperature. At 25 °C the average hydrodynamic radius (R_h) of the block copolymer particles at pH 3 is lower than at pH 9 implying the self-assembling of macromolecules in the latter case. Cloud points of PNIPA₆₀-b-PVIM₉₀ are ~43 °C and ~37 °C at a pH of 3 and 9 and of PNIPA₂₈-b-PVIM₆₂-b-PNIPA₂₉ they are ~35 °C and 31 °C at a pH of 3 and 9. Around cloud point independently of pH, the R_h value for triblock copolymer rises sharply, achieves the maximum value, then falls and reaches the constant value, while for diblock copolymer, it steadily grows after reaching cloud point. The information about polarity of microenvironment around polymer obtained by FS accords with DLS data. Full article

Crosslinked porous microparticles have received great attention as drug delivery systems lately due to their unique set of properties: the capability to form various polymer–drug combinations, low immunogenicity, patient compliance and ability to release drugs in a delayed or controlled manner. Moreover, polymers with betaine groups have shown some unique features such as antifouling, antimicrobial activity, biocompatibility and strong hydration properties. Herein, novel porous zwitterionic microparticles were prepared in two stages. The first step involves the synthesis of porous microparticles based on glycidyl methacrylate, N-vinylimidazole and triethyleneglycol dimethacrylate using the suspension polymerization technique, the second step being the synthesis of zwitterionic porous microparticles by polymer–analogous reaction in presence of sodium monochloroacetate as betainization agent. Both types of microparticles were characterized structurally and morphologically by FT-IR spectroscopy, energy dispersive X-ray analysis, scanning electron microscopy, dynamic vapors sorption and mercury porosimetry. The tetracycline loading into crosslinked and zwitterionic microparticles was also performed, the maximum tetracycline loading capacities being 87 mg/g and 135 mg/g, respectively. The drug release mechanism, elucidated by various mathematical models, is controlled by both diffusion and swelling processes as a function of the zwitterionic and/or porous microparticle structure. Both types of microparticles presented antibacterial activity against the two reference strains used in this study: Escherichia coli and Staphylococcus aureus. Full article

In the context of personalized medicine, the paraxanthine-to-caffeine ratio is an accepted standard for the optimization of the dose-response effect of many pharmaceuticals in individual patients. There is a strong drive towards the development of cheaper and portable devices for the detection of biomarkers, including paraxanthine and caffeine, which requires materials with high binding efficiency and specificity. We designed a recognition unit specific for paraxanthine which can discriminate molecules with small structural differences and can be used to increase the sensitivity of sensors. A number of functional units were screened by nuclear magnetic resonance for their ability to form specific binding interactions with paraxanthine in water and negligible interactions with its structural analogue caffeine. Imidazole was identified as the unit showing the most promising results and its two polymerizable derivatives were evaluated by isothermal titration calorimetry to identify the best monomer. The data suggested that 4-vinylimidazole was the most promising unit forming specific and strong binding interaction with paraxanthine. The calorimetry experiments allowed also the determination of the thermodynamic parameters of all interactions and the association constant values. Optimization of polymerization protocols in water, achieving high monomer conversions and chemical yields, demonstrate the suitability of the selected functional monomer for polymer preparations, targeting the detection of paraxanthine in aqueous environments. Full article

3-(1H,1H,2H,2H-Perfluorooctyl)-1-vinylimidazolium chloride [2126844–17–3], a strong fluorosurfactant with remarkably high solubility in water, was expediently converted into the respective doubly NHC-complexed silver salt with nitrate as counter ion in quantitative yield. Due to its vinyl substituents, [bis(3-(1H,1H,2H,2H-perfluorooctyl)-1-vinylimidazol-2-ylidene)silver(I)] nitrate, Ag(FNHC)₂NO₃, represents a polymerizable N-heterocyclic carbene transfer reagent, thus potentially offering simple and robust access to coordination polymers with crosslinking metal bridges. The compound was characterized by infrared and NMR spectroscopy, mass spectrometry as well as elemental analysis, and supplemented by X-ray single-crystal structure determination. It crystallizes in the monoclinic crystal system in the space group P2₁/c. With 173.3°, the geometry of the Ag-carbene bridge deviates slightly from linearity. The disordered perfluoroalkyl side chains exhibit a helical conformation. Full article

This work aims to synthesize graft copolymers of chitosan and N-vinylimidazole (VI) with different compositions to be used as matrices for the immobilization of cysteine proteases—bromelain, ficin, and papain. The copolymers are synthesized by free radical solution copolymerization with a potassium persulfate-sodium metabisulfite blend initiator. The copolymers have a relatively high frequency of grafting and yields. All the synthesized graft copolymers are water-soluble, and their solutions are characterized by DLS and laser Doppler microelectrophoresis. The copolymers are self-assembled in aqueous solutions, and they have a cationic nature and pH-sensitivity correlating to the VI content. The FTIR data demonstrate that synthesized graft copolymers conjugate cysteine proteases. The synthesized copolymer adsorbs more enzyme macromolecules compared to non-modified chitosan with the same molecular weight. The proteolytic activity of the immobilized enzymes is increased up to 100% compared to native ones. The immobilized ficin retains up to 97% of the initial activity after a one-day incubation, the immobilized bromelain retains 69% of activity after a 3-day incubation, and the immobilized papain retains 57% of the initial activity after a 7-day incubation. Therefore, the synthesized copolymers can be used as matrices for the immobilization of bromelain, ficin, and papain. Full article