Ultrathin films aging dynamics

Remarks on Anomaly Observed in Aging Dynamics in Ultrathin P2CS Films 101... 

Here, we would like to show our recent results on the glass transition dynamics of stacked thin polymer films and the aging dynamics of ultrathin polymer films, as investigated by DSC and DRS. For both cases, heterogeneous dynamics such as the... 

Dielectric measurements were carried out in the same experimental setup described in Sect. 2.2 for the ultrathin films of P2CS with thickness d of 3.7,5.4,9.0,9.5, and 22 nm, in order to investigate the aging dynamics below Tg. The complex dielectric constant (= e — is") was evaluated as a function of temperature T, aging time fw, and the frequency of applied electric field/. The value of was obtained from the value of the complex electrical capacitance of the sample condenser C (= C — iC ), on the assumption that C = Cq is valid, where Cq is the geometrical capacitance of the sample condenser. 

As discussed, the aging dynamics of ultrathin P2CS films are quite different from those of thicker films, and have an anomalous dependence on the thickness and temperature. Here, the microscopic origin for such an anomaly is discussed on the basis of segmental dynamics measurements using DRS. 

As the second topic, we have discussed an anomalous phenomenon observed for the aging dynamics in single ultrathin polymer films. From this study, it has been elucidated that the anomalous increase in dielectric susceptibility observed for isothermal aging processes is strongly associated with the mobile region that exists at the surface and interfacial region of thin polymer films. 

Pye, J.E., Rohald, K.A., Baker, E.A., Roth, C.B. Physical aging in ultrathin polystyrene films evidence of a gradient in dynamics at the free surface and its connection to the glass transition temperamre reductions. Macromolecules 43(19), 8296-8303 (2010)... 

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