Processing Effects on the Physical Properties of Ultrathin Glassy Polymer Films

The physical properties of ultrathin polymer films with thickness less than 100 nm often differ from their bulk counterparts. Two factors are commonly associated with these changes as a function of film thickness. First, the chain mobility of polymers at interfaces is often different compared to that of polymers away from the interface. Second, higher-order structures controlled by the overlap concentration (C*), such as chain entanglements and free volume, can also be affected by dimensional constraints in ultrathin films. However, it has been unclear how these two factors are intertwined in the context of polymer processing methods.

Our previous studies reported that the physical properties of ultrathin films of the same thickness, such as Tg and density, vary depending on the fabrication conditions. We hypothesized this relationship may be due to the higher-order structure, but the details are unclear yet. In this study, we report the relationship between the film thickness and the processing conditions, such as polymer concentration and spinning speed, on the physical properties of ultrathin films.