DOSY NMR as a tool for predicting optimal conditions for hydrogel formation: The case of a hyperbranched polyglycidol cross‐linked with boronic acids. Issue 21 (18th July 2016)

• Record Type: Journal Article
• Authors: Gosecka, Monika; Gosecki, Mateusz; Kazmierski, Slawomir
• Is Part Of: Journal of polymer science. Volume 54:Issue 21(2016)
• Page Start: 2171
• Page End: 2178
• Publication Date: 2016-07-18
• Subjects: boronic cross‐linker -- gels -- polymers -- NMR spectroscopy -- DOSY NMR -- rheology; 547
• DOI: 10.1002/polb.24126
• Languages: English
• ISSNs: 0887-6266

Abstract

ABSTRACT: This article demonstrates the utility of DOSY NMR for the determination of the optimal conditions for the efficient covalent, reversible cross‐linking of macromolecules in water for hydrogel formation. The studied model system was hyperbranched polyglycidol (HbPGL) containing numerous diol groups in peripheral regions and two types of boronic acids, that is, B(OH)4 ⊖ and benzene‐1, 4‐boronic diacid, as cross‐linking agents. Diffusion coefficient changes of a polymer in solution, under the influence of various concentrations of cross‐linking agent and pH, which influences the equilibrium of the reaction between boronic acids and diols, were recorded. These data are consistent with the rheological properties, namely the G ′max ( ω ) of hydrogels prepared under analogous conditions, from more concentrated solutions of HbPGL. This approach appears to be promising as it facilitates avoiding the loss of a large amount of polymer that is necessary for the elaboration of appropriate conditions for network formation in aqueous media. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2016, 54, 2171–2178 Abstract : Diffusion Ordered Spectroscopy NMR (DOSY NMR) measurements of the diffusion coefficient of a polymer in the presence of a cross‐linking agent that have been carried out for semi‐diluted solutions enable the elaboration of the optimal conditions for cross‐linking of hyperbranched polyglycidol with boronic cross‐linkers in more concentrated systems, in the form of hydrogels. The higher the reduction of diffusion coefficient of macromolecules is, the higher the cross‐linking density within hydrogel is observed on the basis of the increase in the maximum of storage modulus plateau.