ORGANIC
LETTERS
2006
Vol. 8, No. 18
4015-4018
Novel Use of Cross-Linked
Poly(N-isopropylacrylamide) Gel for
Organic Reactions in Aqueous Media
Hiromi Hamamoto, Masahiro Kudoh, Hideyo Takahashi, and Shiro Ikegami*
School of Pharmaceutical Sciences, Teikyo UniVersity, Sagamiko,
Kanagawa 199-0195, Japan
Received June 26, 2006
ABSTRACT
A poly(N-isopropylacrylamide) (PNIPAAm) gel cross-linked with quaternized aminoalkyls was designed. A novel recyclable system based on
the external solvent-responsive oil-absorption/elution transition ability of the PNIPAAm gel matrix was then developed.
The study of polymer gels and their response to the external
environment such as temperature, solvent, pH, etc. is of
special interest1 because of their potential as drug delivery
systems, actuators, and separation devices.2 A frequently
studied polymer gel is based on poly-N-isopropylacrylamide
(PNIPAAm).3 When un-cross-linked PNIPAAm polymers
are dissolved in an aqueous solution, the turbidity of the
solution varies due to dissolution and precipitation of the
polymer. When the polymer chains are cross-linked, the
conformational changes lead to macroscopic mechanical
change in the polymer network. Such a conformational
change in the polymer chain induces a swelling/deswelling
transition with the change in external solvent, which allows
control of the absorbency of organic substrates.
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utilization of the temperature-responsive nature of PNIPAAm
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10.1021/ol061562b CCC: $33.50
© 2006 American Chemical Society
Published on Web 08/10/2006