Preparation of Polymer-Immobilized Polyimide Films Using Hot Pressing and Titania Coatings.

Recent studies have revealed that polymer molecules at film surfaces exhibit unique physical properties compared to those in bulk. On the other hand, such a topic has not been extensively focused for the cases of rigid polymers such as polyimide (PI). This study investigated whether hot pressing could induce the immobilization of other polymers, poly(4-vinylphenol) (PVP), on PI film surfaces. Results supported the immobilization of PVP on the PI film surfaces, and the increase of hot-press temperature resulted in the increase of the immobilization amount of PVP. The mechanism of immobilization is discussed considering the effects of hot pressing on the interactions between PVP and PI at the interfaces of their films. Sol-gel titania coatings were further conducted to the obtained PVP-immobilized PI films. The effect of PVP immobilization on formability and the adhesion of titania layers on the film surfaces were evaluated. These results demonstrate that hot pressing of other polymers is a useful approach for the surface modification of PI films, particularly introducing certain functional groups, and indicate that the polymer immobilization mechanism might be correlated with the surface physical properties of PI films.