Mechanism of structural networking in hydrogels based on silicon and titanium glycerolates.

Autor: Khonina TG; I.Ya. Postovsky Institute of Organic Synthesis, Russian Academy of Sciences, 22/20 S. Kovalevskoy/Akademicheskaya St., 620041 Ekaterinburg, Russian Federation. khonina@ios.uran.ru, Safronov AP, Shadrina EV, Ivanenko MV, Suvorova AI, Chupakhin ON
Jazyk: angličtina
Zdroj: Journal of colloid and interface science [J Colloid Interface Sci] 2012 Jan 01; Vol. 365 (1), pp. 81-9. Date of Electronic Publication: 2011 Sep 17.
DOI: 10.1016/j.jcis.2011.09.018
Abstrakt: Formation of organic/inorganic hydrogels based on silicon- and titanium-glycerol precursors synthesized by transesterification of alkoxy derivatives in excess of glycerol was investigated. The precursors in excess of glycerol and obtained gels were studied by chemical and physical methods including gelation kinetics, IR spectroscopy, XRD, dynamic and electrophoretic light scattering, mechanical deformation, which disclosed the basic difference in the gelation mechanism and structure of network in the hydrogels. Due to this difference, the gelation time of silicon- and titanium-glycerol precursors depended on pH or electrolyte addition in an opposite way. In the wide pH range, silicon-glycerol hydrogel was a polymeric single-phase system formed by the polymeric network homogeneously swollen in liquid water/glycerol medium. Flory-Rehner theory applied to the elastic modulus of these gels gave 40-180 monomer base units in the subchains of the network depending on water content in the gel. The mechanism of networking was three-dimensional polycondensation promoted by the electrically charged functional groups attached to the flexible polymeric chains. Electrolyte solutions provided the gelation according to Hofmeister series. Titanium-glycerol hydrogels were heterogeneous colloid systems at pH>1.5 and single-phase polymeric gels at lower pH. Electrolyte solutions provided the gelation according to Schultze-Hardy rule.
(Copyright © 2011 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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