Water‐soluble polymers and gels from the polycondensation between cyclodextrins and poly(carboxylic acid)s: A study of the preparation parameters

Abstract

Native cyclodextrins (CDx) and some of their derivatives were reacted with poly(carboxylic acid)s (PCAs) [citric acid (CTR), 1,2,3,4-butanetetracarboxylic acid (BTCA), and poly(acrylic acid) (PAA)]. These reactions were carried out in the dry state at a temperature greater than 140°C in air or in vacuo. They resulted in water-soluble and insoluble polymers formed by polyesterification between CDx and PCA. In this study, the parameters of the reaction were studied, and their influence on the water solubility or swellability of the obtained polymers was investigated. High reaction temperatures, high PCA/CDx molar ratios, and long reaction times preferably yielded insoluble gels, whereas softer conditions resulted in very soluble polymers.The gels could swell up to 10 times their initial volume in water, and the water-soluble fraction had a solubility of 1 g/mL. A reaction mechanism was proposed that required the use of PCA carrying at least three neighboring carboxylic groups (CTR, BTCA, and PAA), and it was confirmed experimentally by the unsuccessful use of some dicarboxylic acids. A preliminary characterization by Fourier transform infrared spectroscopy and size exclusion chromatography was also conducted.

New crosslinked cast films based on poly(vinyl alcohol): Preparation and physico-chemical properties

“…The CTR being a triacid, residual COOH are present in the three-dimensional network at the end of the reaction. Previous works showed that the esterification occurs from 130°C [11]. A constant temperature of 130±1°C was applied for all this study.…”

Surface modification of electrospun polyester nanofibers with cyclodextrin polymer for the removal of phenanthrene from aqueous solution

“…The chemical reaction cannot occur between cyclodextrin (CD)/citric acid (CTR) and PET nanofibers directly, since PET, a polymer based on terephtalic acid and ethylene glycol, does not contain free reactive groups. Therefore, we modified the surface of the electrospun PET nanofibers through the polymerization reaction between CTR and CD [21,24,25]. Water-insoluble cyclodextrin polymer (CDP) network was formed by the crosslinking reaction between CD and CTR [26].…”

“…Initially, electrospun PET nanofibrous mats were impregnated in a solution of CD, CTR, and sodium hypophosphite (SHPI, catalyst), and then dried, followed by curing at 180 • C for 7 min. CTR turn into a cyclic anhydride intermediate by thermal dehydration at elevated temperature, and then hydroxyl groups of CD reacted with the carboxyl groups of citric acid [25]. The mechanism of the CDP formation is schematically described in Fig.…”

“…Due to crosslinked structure, the CDP is stable and water-insoluble [27,28]. Thereby, surface modification of CDP onto PET nanofibers is permanent and can resist to leaching or washing process [21,24,25,29]. The resulting CDP having the essential structural characteristics of CD was not covalently fixed to the PET nanofibers, but it was physically adhered or was entangled onto PET fiber matrix [21,24].…”

Inclusion and Functionalization of Polymers with Cyclodextrins: Current Applications and Future Prospects

“…Covalent polymer networks containing cyclodextrins are of great interest because their croslinked macromolecular structure has a cooperative action between the cyclodextrin cavities, or between the cavities and the polymeric network, in the complexation and adsorption of water soluble components. From this perspective, CD polymers were prepared by solubilization of citric acid as crosslinking agent and sodium hypophosphite as catalyst [17,18], and they were used to improve the complexation of some drugs. These polymers with an anionic character present low toxicity and an environmentally friendly composition.…”