Title

Characteristic Role of Crosslinker on Thermally Induced Volumetric Contraction-expansion Processes in Poly(N-isopropylacrylamide) Networks and Water Systems

Abstract

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.

Department(s)

Chemistry

Sponsor(s)

United States. Department of Energy

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2009 Wiley-Blackwell, All rights reserved.


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