An efficient pathway to the elaboration of glassy amphiphilic ester based hydroxyethyl cellulose and ionic liquids

Hydroxyethyl cellulose (HEC) is considered one of the most important hydro-soluble cellulose derivatives, thanks to its biocompatibility and biodegradability profile. In this work, a facile synthesis methodology was developed to graft ionic liquids onto the HEC ester. Firstly, a low Tg (glass transition temperature) glassy brominated hydrophobic ester based on HEC was prepared. By regioselective nucleophilic substitution of bromine with imidazole and pyridine derivatives, HEC-ILs (ionic liquids) with a high degree of substitution were elaborated in a second step. The synthesized HEC-ILs were characterized by nuclear magnetic resonance (1H, 13C NMR), elemental analysis (CHNO), Fourier transform infrared spectroscopy-Attenuated total reflection (FTIR-ATR), X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy. Zeta potential was used to verify the presence of permanent positive charge. Contact angle measurements were exploited to follow the reorganization of the surface of HEC-ILs in contact with water. A theoretical study was carried out to investigate the intra- and intermolecular interactions of polymer chains. The prepared cationic HEC derivatives have attractive properties such as their amphiphilic and glassy character, solubility in water, and a permanent positive charge. Such properties open a wide range of applications in the field of drug delivery and the complexation of anionic molecules.Post-print / Final draf

Ethnobotanical use, phytochemical study, and antioxidant activity of Globularia alypum

This work aimed to highlight the biological effects of Globularia alypum L., a medicinal plant widely used in phytotherapy.Globularia alypum L. is a plant used in traditional medicine in Morocco, the crude extracts prepared from the leaves were obtained using maceration in methanol, ethyl acetate, butanol, and water. The content of total polyphenols was determined using the Folin-Ciocalteu reagent, the first range was for the ethyl acetate extract, followed by butanol, methanol, and aqueous extracts, respectively. The flavonoids amount was determined using the aluminum chloride colorimetric method, the methanolic extract presented the highest content of flavonoids, followed by the one of butanol, then the ethyl acetate and aqueous extracts. The antioxidant activity was carried out using the anti-free radical method based on 2,2-diphenyl-1-picrylhydrazyle (DPPH), the IC50 values were estimated for methanolic, ethyl acetate, butanol and aqueous extracts while that of BHT and ascorbic acid. The high phenolic and flavonoid amounts as well as the antioxidant potential of the extracts indicated that the G. alypum could be exploited as a source of natural antioxidants

Dissolution mechanism of cellulose in a benzyltriethylammonium/urea deep eutectic solvent (DES): DFT-quantum modeling, molecular dynamics and experimental investigation

In this paper, a benzyltriethylammonium/urea DES was investigated as a new green and eco-friendly medium for the progress of organic chemical reactions, particularly the dissolution and the functionalization of cellulose. In this regard, the viscosity–average molecular weight of cellulose ([M with combining macron]w) during the dissolution/regeneration process was investigated, showing no significant degradation of the polymer chains. Moreover, X-ray diffraction patterns indicated that the cellulose dissolution process in the BTEAB/urea DES decreased the crystallinity index from 87% to 75%, and there was no effect on type I cellulose polymorphism. However, a drastic impact of the cosolvents (water and DMSO) on the melting point of the DES was observed. Besides, to understand the evolution of cellulose–DES interactions, the formation mechanism of the system was studied in terms of H-bond density and radial distribution function (RDF) using molecular dynamics modeling. Furthermore, density functional theory (DFT) was used to evaluate the topological characteristics of the polymeric system such as potential energy density (PED), laplacian electron density (LED), energy density, and kinetic energy density (KED) at bond critical points (BCPs) between the cellulose and the DES. The quantum theory of atoms in molecules (AIM), Bader's quantum theory (BQT), and reduced density gradient (RDG) scatter plots have been exploited to estimate and locate non-covalent interactions (NCIs). The results revealed that the dissolution process is attributed to the physical interactions, mainly the strong H-bond interactions.Post-print / Final draf

New Ethylenediamine Crosslinked 2D-Cellulose Adsorbent for Nanoencapsulation Removal of Pb (II) and Cu (II) Heavy Metal Ions: Synthesis, Characterization Application, and RSM-Modeling

The main objective of the present work is to elaborate on a new eco-friendly and efficient adsorbent designated for aquatic micropollutants removal. However, the synthesis of the Ethylenediamine Crosslinked 2D-Cellulose green adsorbent was carried out successfully, by partial grafting of benzyl entities onto hydroxyl groups of HEC, and crosslinking with ethylenediamine ED. Further, the new ethylenediamine crosslinked 2D-Cellulose was used as a biosorbent for nanoencapsulation removal of copper and lead heavy metal ions from aqueous solutions. The proposal chemical structures of unmodified and modified materials were confirmed using FTIR, XRD, TGA, and SEM–EDX analysis. Furthermore, many parameters of the optimization for Pb (II) and Cu (II) in terms of removal efficiency including pH, adsorbent amount, and contact time were optimized by response surface methodology with a Box–Behnken design. Based on the desirability optimization with three factors, the maximal removal was 99.52% and 97.5% for Pb(II) and Cu(II), respectively and was obtained at pH = 5.94, 22.2 mg as the optimal adsorbent amount, and 21.53 min as contact time

Structural and impedance spectroscopic study of Zn-substituted Ba5CaTi2Nb8O30 tetragonal tungsten bronze ceramics

International audienceZn-doped tungsten bronze compounds derived from Ba5CaTi2Nb8O30, with Ba5CaTi2-xZnxNb8O30 composition (x=0; 0.04 and 0.08) were synthesized by the conventional solid-state reaction route. Both solubility of Zn in Ba5CaTi2Nb8O30 and tungsten bronze formation with the P4bm space group were verified by the Rietveld method using X-ray diffraction data. The average crystallite size was of the order of 0.08 μm according to Scherrer's formula. SEM micrographs of Ba5CaTi2-xZnxNb8O30 ceramics showed high densification, low porosity, thus a homogeneous grain distribution of different sizes over the entire surface. The average grain size was in the range of 1.3 to 1.6 μm. The frequency-dependent electrical properties were analyzed by complex impedance spectroscopy. Different types of studies such as the Nyquist plot, real and imaginary impedance, conductivity, modulus formalism, and charge carrier activation energy were used to explain the microstructure-electrical properties relationships

Relationship between structural and dielectric properties of Znsubstituted Ba5CaTi2−xZnxNb8O30 tetragonal tungsten bronze

International audienceBa5CaTi2-xZnxNb8O30 ceramics with (x=0, 0.04, and 0.08) were synthesized by conventional solid-state reaction method at 1300°C for 6 hours. The effects of the Ti/Zn ratio on structural and dielectric properties were studied by changing the value of x. The pure phase formation of all prepared Ba5CaTi2-xZnxNb8O30 compositions was confirmed by X-ray diffraction. The refinement of the (XRD) data by the Rietveld method confirmed the tetragonal crystal structure with the space group P4bm at room temperature. Scanning electron microscopy (SEM) of Ba5CaTi2-xZnxNb8O30 ceramics shows good sinterability, low porosity and uniform distribution of grains of unequal size over the entire surface in all samples. The average grain size is in the range of 1.3 to 1.6 μm. The frequency-dependent dielectric properties were examined by complex impedance spectroscopy in the temperature range of 50°C to 420°C where a structural phase transition was observed for all samples

Controlled synthesis of linear and multi ARM amphiphilic copolymers consisting of P4VP and PCL for tailored nano-aggregate formation

This work focuses on the synthesis and characterization of amphiphilic block copolymers with varying architectures using controlled polymerization via RAFT polymerization. The study explores the production of diverse nano-aggregates, ranging from micelles to complex structures like vesicles, by leveraging the destabilization of micelle formation through multi-arm topologies. The chosen polymer chains, P4VP and HEMA-PCL, exhibit inter and intramolecular interactions that facilitate phase separation and the formation of nano-aggregates in different solvent mixtures. The Structural characterizations using NMR, FTIR, and SLS have demonstrated good control over the architecture of the copolymers. The physicochemical properties of the copolymers are discussed, along with a detailed analysis of supramolecular association in different solvent systems, revealing the strong influence of copolymer architecture and arm number on the nature of the formed aggregates. The multi-arm structure stabilizes at much lower CAC and in very short time (30 min) compared to that found in the case of the linear structure. In addition, the results shown that, the multi-arm structure always allows the formation of vesicles no matter what the selective solvent is, which indicate that the formation of the aggregates is driven by the topology of copolymer and note by the medium polarity.Post-print / Final draf

Enhanced performance of novel hydroxyethyl cellulose grafted amide-based microcapsules by catalyzed interfacial polymerization: Synthesis, characterization, and theoretical studies

Due to their biodegradability, biocompatibility, non-toxicity, and affordable manufacture from renewable resources, hydroxyethyl cellulose (HEC) and its derivatives have gained growing interest in a variety of sectors. In light of this, HEC and HEC-branched-amide (HECA) were used to develop new polyurethane and polycarbamoyle amide-based microcapsules. The structure of the HECA prepolymer and the elaborated microcapsules were examined using FT-IR, NMR, DRX, DLS, SEM, TGA, and Zeta Potential. The Polycarbamoyle amide microcapsules were prepared by catalyzed interfacial polymerization between the diisocyanate and the amide group of HECA. The enhanced kinetics of carbamoyle amide membrane formation using copper catalyzed polymerization is shown to have an advantage in maintaining the characteristics of the microcapsules. The stability and resistance of the microcapsules under temperature and pH conditions were also investigated. Due to strong bidentate interactions between the carbamoyle amide groups in the membrane, the microcapsules based on these groups display great stability in front of the microcapsules made of polyurethane. Theoretical studies have demonstrated these interactions, while the FT-IR results have supported these findings. The obtained results prove a positive enhancement in limonene encapsulation efficiency as the amount of carbamoyle amide groups within the membrane of the microcapsules is increased, reaching a maximum value of 96.84%. The shape has developed into a perfectly spherical, hard shape with a typical microcapsule diameter of 9 μm.Post-print / Final draf

Homogeneous succinylation of cellulose acetate : design, characterization and adsorption study of Pb(II), Cu(II), Cd(II) and Zn(II) ions

In this study, the removal of Pb(II), Cu(II), Cd(II), and Zn(II) ions from aqueous solutions was investigated using succinic anhydride modified cellulose monoacetate. In the first part, the cellulose acetate was successfully succinylated in a homogenous medium of DMF using 4-dimethylaminopyridine (DMAP) as a catalyst. The obtained material (AcS) was analyzed by FTIR and CP/MAS 13C NMR Spectroscopy, thermogravimetry analysis and DRX patterns. The titration method was used to determinate the degree of hydroxyl group substituted by carboxyl group (DS) and was found to be 1.36. In the second part, the Bach technique was used to study the effects of pH, contact time, concentration of metals, ionic selectivity and regeneration. Maximum sorption capacities of AcS for Pb(II), Cu(II), Cd(II), and Zn(II) were 241.81, 133.76, 156.61 and 73,58 mg.g-1, respectively. The Langmuir isotherm and the pseudo second order kinetic models provided best fit to the experimental data of metal ion sorption. The nature of the adsorption process was exothermic and spontaneous in nature with negative values of ΔG° and ΔH°. Regeneration of the modified cellulose acetate was accomplished using nitric solution and showed high stability and good recyclability