Characteristic Role of Crosslinker on Thermally Induced Volumetric Contraction-expansion Processes in Poly(N-isopropylacrylamide) Networks and Water Systems
In this work, the degree of crosslinking on the volumetric contraction-expansion processes of hydrogels made of poly(N-isopropylacrylamide) (NIPA) (initial amount: Cm) with varied amount (z) of crosslinking agent methylene-bis-acrylamide (BIS) in reference to most commonly used NIPA gel that was synthesized with Cm = 700 mM and z = 8.6 mM was investigated by applying our recently developed pycnometry. We focused on characteristic role of four polymeric NIPA residues directly bonded to a single BIS molecule by evaluating the total volume of gels per four NIPA residues directly bonded to a BIS molecule, plus associated water [sp(gel)(NIPA)bonded)(T)], and the corresponding number of water molecules per four NIPA residues [Ns(gel)(NIPA)bonded)(T)]. We elucidated how these quantities characteristically contribute to changes in the volumetric contraction-expansion processes of hydrogels. a comparison of these quantities with the corresponding quantities for (NIPA)unbonded residues clearly revealed a significant structural difference between (NIPA)bonded and (NIPA)unbonded.
T. Tokuhiro and A. Tokuhiro, "Characteristic Role of Crosslinker on Thermally Induced Volumetric Contraction-expansion Processes in Poly(N-isopropylacrylamide) Networks and Water Systems," Journal of Applied Polymer Science, Wiley-Blackwell, Jun 2009.
The definitive version is available at https://doi.org/10.1002/app.29670
United States. Department of Energy
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