It may be counterintuitive that a step of smaller activation energy would be the rate-limiting reaction. However, this result is not strange because the rate of the reaction depends not only on the activation energy but also on the frequency factor in the Arrhenius equation. The relationship between the shift factor and activation energy shown in eq. ( ) is based on the Arrhenius equation, which describes the reaction rate constant k with the frequency factor A and the activation energy ∆E as 𝑘 = 𝐴exp B-∆O "L C. It is impossible to determine the frequency factor or rate constant in this experiment since the shift factor reflects only the activation energy. If the disappearance of the layered structure is regarded as a sequential reaction, the overall reaction rate k is determined by the elementary reaction with the smallest rate constant. That is, it is possible for a process with low activation energy, i.e., bulk viscous flow, to be the rate-limiting process depending on the frequency factor. The disappearance of the layered structure is attributed to both the segmental substitution on the solid surface and the random coiling of the PDMS molecules.