We report that the reduction of the diffusion coefficient of rhodamine B mo
lecules in a poly(N-isopropylacrylamide) gel is well explained by the pore
size effect of a gel network. The diffusion coefficient was calculated from
the time development of the concentration profile at different temperature
. The coefficient decreased with decreasing the shrink ratio that is a func
tion of temperature. Assuming the gel network is homogeneous, the average v
alue of the pore size could be estimated as a function of the shrink ratio.
The pore size effect on the diffusion coefficient via the apparent viscosi
ty was well evaluated based on the probability of which a rhodamine B molec
ule passes through a pore. (C) 1999 Published by Elsevier Science B.V. All
rights reserved.