Swelling Kinetics and Rheological Behavior of Chitosan-PVA / Montmorillonite Hybrid Polymers

This study involved preparation of hybrid polymer systems based on chitosan-poly(vinyl alcohol) (PVA) blends and modified Montmorillonite. These structures were characterized through microscopy and infrared spectroscopy; swelling measurements were performed to explore polymer absorbency. The behavior of polymer systems was studied through steady and oscillatory shear rheology. Results showed that more stable blend membranes were formed due to the strong interaction between chitosan and PVA. The membranes exhibited appreciable water uptake and were sensitive to saline solution with a slight shrinking.Shear viscosity was described by Cross model to characterize non-Newtonian behavior of all polymer solutions, the shear thinning increases with PVA content, while viscosity increases with chitosan extent. In oscillatory experiments, it was observed that all measured viscoelastic properties were influenced by blends composition and clay content. For all samples, results show a typical behavior of an entangled system in the case of semi-dilute macromolecular viscoelastic fluids. The dynamic moduli exhibited higher values for blends, compared with values of neat polymers, which are an indication of a good stability and a tendency of gel formation. Therefore, the prepared chitosan-PVA systems, which exhibited high swelling degrees and suitable viscoelastic properties, have promising applications in tissue engineering and membrane processes

Combining Cellulose and Cyclodextrins: Fascinating Designs for Materials and Pharmaceutics

Cellulose and cyclodextrins possess unique properties that can be tailored, combined, and used in a considerable number of applications, including textiles, coatings, sensors, and drug delivery systems. Successfully structuring and applying cellulose and cyclodextrins conjugates requires a deep understanding of the relation between structural, and soft matter behavior, materials, energy, and function. This review focuses on the key advances in developing materials based on these conjugates. Relevant aspects regarding structural variations, methods of synthesis, processing and functionalization, and corresponding supramolecular properties are presented. The use of cellulose/cyclodextrin conjugates as intelligent platforms for applications in materials science and pharmaceutical technology is also outlined, focusing on drug delivery, textiles, and sensors

Modification chimique des polymères cellulosique : griffage et formation de complexes d'inclusion avec la cyclodextrine

113 p. : ill. ; 30 cmCe travail est consacre a la modification des polymères cellulosiques, en vue de leur conférer des nouvelles propriétés antibactériennes et absorbantes d'un coté, et d'un autre cote de leur attribuer de nouvelles propriétés adsorbantes pour l'utilisation dans l’élimination des colorants et des composes organiques de l'eau polluée. Dans ce but, trois méthodes de modification des polymères ont été exploitées, Dans une première partie, la fonctionnarisation a été effectuée par imprégnation des supports cellulosiques dans des solutions d'ammoniums quaternaires a différentes chaines alkyl aliphatiques, puis leur activité antibactérienne a été étudié. Dans la seconde étape, et afin de montrer l'importance de la modification chimique, un complexe entre la ƒہ-cyclodextrine et le methylol acrylamide a été synthétisé, puis greffe et copolymérise sur les fibres de cellulose activée. L'inclusion de l'acide benzoïque dans la cavité de la cyclodextrine a pour but d'un agent antibactérien. Dans la troisième étape, les supports cellulosiques ont été traites par la thio-urée pour obtenir un thiocarbamate de cellulose. Pour fonctionnaliser ce dernier, l'acrylonitrile a été par la suite greffe puis copolymérisé sur la chaine macromoléculaire du thiocarbamate. Le greffage et l’imprégnation ont été confirmes par des analyses FTIR et MEB. Pour confirmer l’activité antibactérienne des polymères fonctionnalisés, des tests bactériologiques (norme AATCC100-1999) ont été effectues avec des souches Gram+ (Bacillus subtilis) et Gram- (Escherichia coli et Pseudomonas aeruginosa). La capacité d'absorption des échantillons modifies a été nettement améliorée, L'application de ces matériaux dans l'adsorption des colorants (colorant réactif, anionique, cationique) et des composes organiques (phénol, hydroquinone) a différents pH a montre des résultats encourageants pour leur utilisation dans la décoloration des effluents industriel

Développement de biomatériaux à base de dérivés cellulosiques fonctionnalisés par la B-cyclodextrine et les ammoniums quaternaires

75 p. : ill. ; 30 cmCe travail est consacré à la synthèse et à la fonctionnalisation des polymères cellulosiques, en vue de leur conférer des nouvelles propriétés antibactériennes et absorbantes. La fonctionnalisation a été effectuée par imprégnation du coton et de la pâte de cellulose dans une solution d'ammoniums quaternaires à différentes chaînes alkyl aliphatiques. Afin de montrer l'importence de la modification chimique, le greffage de la B-cyclodextrine sur la viscose et sur le coton a été effectué. Le greffage et l'imprégnation ont été confirmés par des analyse FTIR et ME

Synthesis and characterization of porous materials containing modified cellulose by β-Cyclodextrin for the application in processing industrial liquid waste

The cellulose made up the principal structure of many plants. The content varies according to the vegetable species, from approximately 40% in wood, to 95-99% in cotton fibers. Several ways are possible to bring an additional function to cellulose: new fibers, modification of the fibrous structure, physical or chemical treatment by a surface treatment. And due to the contribution of functions, the formerly passive cellulose becomes active. Capacity of cyclodextrins to facilitate the inclusion of hydrophobic molecules, and others chemical derivatives like the dyes, can be exploited to obtain new porous materials modify with particular performances. In this work, a porous cellulosic material modifies was obtained by chemical modification and fixing of β-cyclodextrin on polymeric surface. The results were confirmed by infra-red analysis (FTIR) and scanning electron microscopy (SEM). The experiments of adsorption of balance of a reactive dye were made in aqueous solutions for 48 hours. Our results indicate the formation of a permanent chemical bond between the β - cyclodextrin and the fibrous material, and the modification is done without change of the polymer structure, the inclusion of the molecules of dyes in the cavity of cyclodextrin is due to the several interactions. The results of dye adsorption in aqueous medium show the aptitude of porous materials to fix the dangerous industrial dyes, and used in the processing industrial liquid wast

Study of the kinetics adsorption of organic pollutants on modified cellulosic polymer using ultraviolet-visible spectroscopy

We report a study on the formation of the complex acrylamidomethylated- β-cyclodextrin, then on the grafting on cellulosic polymer. The grafting is initiated by ceric ions Ce(IV) and confirmed by infrared spectroscopy analysis (FTIR). Scanning electron microscopy (SEM) analysis was carried out to evaluate properties of structure and surface of grafted polymers. The experiments of the study of adsorption of balance of phenol and hydroquinone and a reactive dye, acid dyes, and cationic dyes using ultraviolet-visible microscopy were made in aqueous solutions for 24 hours at different pH. Our results indicate formation of a permanent chemical bond between β-cyclodextrin and polymers material. The cellulosic polymers can effectively be modified without significant change in the structural properties. Then, the results of organic pollutants adsorption in aqueous medium show the aptitude of the polymer modified to fix the phenol derivatives and synthetics dyes and used in the processing industrial liquid waste. The differences in adsorption capacities may be due to the effect of dye structure. The negative value of free energy change indicated the spontaneous nature of adsorptio

Biotreatment on cellulose fluff pulp : quaternary ammonium salts finish and grafting with β -cyclodextrin

For its potential performances to be expanded, cellulose needs to be processed in different ways. Therefore, an object of the present work was to provide a chemical modification of cellulose through: a specific finish with two quaternary ammonium salts (namely Aliquat 336 and Aliquat 1529, respectively). Chemical grafting of β -cyclodextrin derivative ( β -CD) onto fibers followed by the inclusion of benzoic acid in the grafted CD cavities as a probe chemical. Physicochemical properties and performances of the untreated and treated fibers have been determined with infrared spectra, microscopy, swelling measurements, antimicrobial finishing tests, and dye adsorption. Our results show that cellulose fibers can be efficiently modified with no significant changes in its structural and surface properties; the treated fibers show an attractive behavior in swelling, dye adsorption and antibacterial activit