Hostname: page-component-586b7cd67f-l7hp2 Total loading time: 0 Render date: 2024-11-25T15:38:09.996Z Has data issue: false hasContentIssue false

Phase Behavior and Shrinking Kinetics of Thermo-Reversible Poly(N-Isopropylacrylamide-2-Hydroxyethyl Methacrylate)

Published online by Cambridge University Press:  31 January 2011

Christine M Leon
Affiliation:
[email protected], Arizona State University, Harrington Department of Bioengineering, Tempe, Arizona, United States
Francisco J Solis
Affiliation:
[email protected], Arizona State University, Division of Mathematical and Natural Sciences, Glendale, Arizona, United States
Brent L Vernon
Affiliation:
[email protected], Arizona State University, Harrington Department of Bioengineering, Tempe, Arizona, United States
Get access

Abstract

We study the thermodynamic properties of solutions of the physically gelling poly(N-isopropylacrylamide-2-hydroxyethyl methacrylate) [poly(NIPPAm-HEMA)]. We construct its phase diagram and characterize its kinetics of phase separation. This material belongs to a class of thermosensitive, “smart” polymers, that exhibit complex phase behavior. The copolymer studied is liquid at low temperatures and undergoes phase separation near 28°C, with negligible dependence on concentration. Above the transition temperature we observe coexistence between a polymer-dilute solution and a gel. We show that, upon quick heating, liquid solutions form a homogeneous gel that phase separates (shrinks) from a dilute polymer solution. We find that the evolution of the gel volume fraction is well described by a double exponential decay, indicating the presence of two shrinking regimes in a close parallel to the behavior of chemically cross-linked gels. The first stage is characterized by quick water ejection. In the second stage, slower shrinking is observed associated with internal reorganization of the polymers that allows the creation of gel-forming contacts.

Type
Research Article
Copyright
Copyright © Materials Research Society 2009

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1 Vernon, B. and Martinez, A., J. Biomat. Sci., Polym. Ed., 16, 1153 (2005).10.1163/1568562054798536Google Scholar
2 Jeong, B. and Gutowska, A., Trends. Biotech., 20, 305 (2002).10.1016/S0167-7799(02)01962-5Google Scholar
3 Vernon, B., Kim, S.W., and Bae, Y.H., J. Biomed. Mat. Res., 51, 69 (2000).10.1002/(SICI)1097-4636(200007)51:1<69::AID-JBM10>3.0.CO;2-63.0.CO;2-6>Google Scholar
4 Cui, Z., Lee, B.H., and Vernon, B.L., Biomacromolecules, 8, 1280 (2007).10.1021/bm061045gGoogle Scholar
5 Jeong, B., Bae, Y.H., Lee, D.S., and Kim, S.W., Nature, 388, 860 (1997).10.1038/42218Google Scholar
6 Matsumaru, Y., Hyodo, A., Nose, T., Ito, S., Hirano, T., and Ohashi, S., J. Biomater. Sci., Polym. Ed., 7, 795 (1996).10.1163/156856296X00138Google Scholar
7 Bates, F.S., Science, 22, 898 (1991).10.1126/science.251.4996.898Google Scholar
8 Semenov, A.N., Macromolecules, 31, 1373 (1998).10.1021/ma970616hGoogle Scholar
9 Dormidontova, E.E., Macromolecules, 35, 987 (2002).10.1021/ma010804eGoogle Scholar
10 Suzuki, A., Yoshikawa, S., and Bai, G., J. Chem. Phys. 111, 360 (1999).10.1063/1.479278Google Scholar
11 Maeda, Y., Yamauchi, H., Fujisama, M., Sugihara, S., Ikeda, I., and Aoshima, S., Langmuir, 23, 6561 (2007).10.1021/la700387wGoogle Scholar
12 Solis, F.J., Weiss-Malik, R., and Vernon, B., Macromolecules, 38, 4456 (2005).10.1021/ma047895aGoogle Scholar
13 Watzlawek, M., Likos, C.N., and Löwen, H., Phys. Rev. Lett., 82, 5289 (1999).10.1103/PhysRevLett.82.5289Google Scholar
14 Song, M.J., Lee, J.H, Ahn, J.H., Kim, D.J., and Kim, S.C., J. Polym. Sci. Part A: Polym. Chem., 42, 772 (2004).10.1002/pola.10851Google Scholar