Multi-scale characterization of surface-crosslinked superabsorbent polymer hydrogel spheres

Sooho Chang, Minsu Kim, Seunghee Oh, Ji Hong Min, Donyoung Kang, Changsun Han, Taebin Ahn, Won-Gun Koh, Hyungsuk Lee

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

In order for super absorbent polymer (SAP) to be used in an application undergoing mechanical stress, it is necessary to regulate its shape and mechanical properties, which have been rarely studies. Here, spherical SAPs were prepared through inverse-suspension polymerization of partially neutralized acrylic acid monomers with ethylene glycol diacrylate (EGDA) crosslinkers. The surface region of SAP spheres was additionally crosslinked with ethylene glycol diglycidyl ether (EGDE) to improve the mechanical properties, producing a core-shell structure characterized by lightly crosslinked core and more densely crosslinked shell. Mechanical responses of the cross-linked SAP to global compression were obtained from experiments using a custom-made indentation device. The local mechanical properties of crosslinked surface were measured by atomic force microscopy. While the global responses of SAP were similar independent of surface crosslinking, the modulus of crosslinked surface increased as concentration of EGDE. In our experimental conditions, the surface modulus of surface crosslinked SAP was increased 2.7 folds, compared to that of SAP without surface crosslinking. The structure of SAP spheres with and without surface crosslinking was also visualized, and thickness of crosslinked surface was measured with fluorescence microscopy. We found that the thickness of crosslinked surface increased with increasing EGDE concentration but became saturated. Furthermore, a computational model was developed for core-shell SAP spheres using the measured mechanical properties, and was utilized to predict the thickness of crosslinked surface. Finally, we propose an analytical diffusion model that describes the diffusion and surface crosslinking reaction to elucidate the mechanism over which the mechanical and diffusion properties of SAP sphere are determined.

Original languageEnglish
Pages (from-to)174-183
Number of pages10
JournalPolymer
Volume145
DOIs
Publication statusPublished - 2018 Jun 6

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Hydrogel
Hydrogels
Polymers
Ethylene glycol
Crosslinking
Ethers
Mechanical properties
Ethylene Glycol
Fluorescence microscopy
Indentation
Acrylics
Atomic force microscopy
Suspensions
Compaction
Monomers
Polymerization

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

Cite this

Chang, Sooho ; Kim, Minsu ; Oh, Seunghee ; Min, Ji Hong ; Kang, Donyoung ; Han, Changsun ; Ahn, Taebin ; Koh, Won-Gun ; Lee, Hyungsuk. / Multi-scale characterization of surface-crosslinked superabsorbent polymer hydrogel spheres. In: Polymer. 2018 ; Vol. 145. pp. 174-183.
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Multi-scale characterization of surface-crosslinked superabsorbent polymer hydrogel spheres. / Chang, Sooho; Kim, Minsu; Oh, Seunghee; Min, Ji Hong; Kang, Donyoung; Han, Changsun; Ahn, Taebin; Koh, Won-Gun; Lee, Hyungsuk.

In: Polymer, Vol. 145, 06.06.2018, p. 174-183.

Research output: Contribution to journalArticle

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AU - Chang, Sooho

AU - Kim, Minsu

AU - Oh, Seunghee

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AU - Ahn, Taebin

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