|
|||||
|
|
Temperature dependence of free volume of polyacrylamide gels studied by positron lifetime measurements |
|
| Authors: | Kenji Ito Yusuke Ujihira Takashi Yamashita Kazuyuki Horie |
| Affiliation: | Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan |
| Abstract: | Changes of positronium (Ps) cavity radii in polyacrylamide and poly(N-isopropylacrylamide) gels were studied from 120 to 300 K by positron lifetime technique and it has been shown that the Ps cavity radius in the hydrogels changes by three or four stages. Temperature dependence of the Ps cavity radius exhibits variations similar to common polymers around the glass transition temperature. Hydrophilicity of the polymer chains significantly affects the Ps cavity radius just below 273 K. These results suggest an important role of free volume on the state of water in hydrogels. |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ | |