Reentrant behaviour in polyvinyl alcohol-borax hydrogels

Polyvinyl alcohol (PVA) hydrogels, cross-linked with varying concentrations of borax, were studied with small angle neutron scattering (SANS), x-ray diffraction (XRD) and differential thermal analysis (DTA). The SANS data satisfy the Ornstein-Zernike approximation. The hydrogels are modelled as PVA...

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Bibliographic Details
Published inMaterials research express Vol. 5; no. 1; pp. 15315 - 15324
Main Authors Lawrence, Mathias B, Desa, J A E, Aswal, V K
Format Journal Article
LanguageEnglish
Published IOP Publishing 01.01.2018
Subjects
borax
DTA
PVA
SANS
XRD
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Summary:Polyvinyl alcohol (PVA) hydrogels, cross-linked with varying concentrations of borax, were studied with small angle neutron scattering (SANS), x-ray diffraction (XRD) and differential thermal analysis (DTA). The SANS data satisfy the Ornstein-Zernike approximation. The hydrogels are modelled as PVA chains bound by borate cross-links. Water occupies the spaces within the three-dimensional hydrogel network. The mesh size indicates reentrant behaviour i.e. at first, increases and later decreases as a function of borax concentration. The behaviour is explained on the basis of the balance between the charged di-diol cross-links and the shielding by free ions in the solvent. XRD and DTA show the molecular size of water in the solvent and the glass transition temperature commensurate with reentrant behaviour.
Bibliography:MRX-106276.R1
ISSN:2053-1591
2053-1591
DOI:10.1088/2053-1591/aaa6e6