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Dynamics of Sodium Ions and Water in Swollen Superabsorbent Hydrogels as Studied by 23 Na‐ and 1 H‐NMR
Author(s) -
Guo Xiaoai,
Theissen Solveig,
Claussen Jan,
Hildebrand Viet,
Kamphus Juliane,
Wilhelm Manfred,
Luy Burkhard,
Guthausen Gisela
Publication year - 2019
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201800350
Subject(s) - diffusion , swelling , chemistry , pulsed field gradient , ion , self healing hydrogels , sodium , relaxation (psychology) , molecular dynamics , isotopes of sodium , self diffusion , polymer chemistry , aqueous solution , molecule , analytical chemistry (journal) , materials science , organic chemistry , computational chemistry , thermodynamics , composite material , psychology , social psychology , physics , self service , marketing , business
Dynamics of sodium ions and water in swollen superabsorbent polymer (SAP) hydrogels are studied by 23 Na‐ and 1 H‐NMR, respectively. The apparent diffusion coefficients of water in swollen SAPs, probed by 1 H pulsed field gradient NMR, decreases with increasing diffusion time. The degree of hindrance depends on structural and synthesis parameters. It is quantified within a tortuosity model. Based on the results, the swelling degree has the highest impact on the ion mobility, apart from synthesis parameters leading to different levels of physical and chemical crosslinks. 23 Na‐NMR relaxation and diffusion reveal the 23 Na + mobility in swollen SAPs. A higher degree of neutralization leads to faster relaxation and to a smaller apparent diffusion coefficient. Surface crosslinking restricts water mobility, but has a smaller impact on the dynamics of sodium ions. The experimental results indicate an influence of SAP structure on the dynamics of ions and water molecules.