Glass-fabric reinforced film-based foldable cover window film and auxetic structured film with negative poisson’s ratio

Abstract

A substrate in flexible displays plays an important role because it provides a stable base for the fabrication process and the devices while providing the deformability. Therefore, it requires a high mechanical strength while having flexibility, thermal robustness, and dimensional stabilities for high temperature process. Satisfying the demands, glass-fabric reinforced hybrid films that consists of glass-fabric and siloxane hybrid material has been suggested as a candidate for the flexible displays. The siloxane hybrid materials that have flexible organic moieties and thermo-chemically stable inorganic moieties are not only used for the glass-fabric reinforced hybrid films, but for the flexible hard coating. Also, the glass-fabric reinforced plastic films can be utilized for other electronics substrate by differing the matrix materials. For example, a more flexible film is fabricated by reinforcing an elastomer with the glass-fabric. In this study, the glass-fabric reinforced hybrid film is integrated with the siloxane hybrid-based hard coating, giving a substrate/hard coating all-in-one film. It can be utilized as a cover window for foldable display because of its high flexibility, mechanical strength, optical transparency as well as the reliability under various folding situations such as cyclic folding and static folding states in severe climates. Also, an omni-directionally stretchable film having continuous surface and negative Poisson’s ratio is realized by the reinforcement of stretchable elastomer with robust glass-fabric. The omni-directionally stretchable substrate film consists of glass-fabric reinforced area that comprises an auxetic structure that exhibit negative Poisson’s ratio, and the pristine elastomer that fills the open areas of the auxetic structure. The maximum negative Poisson’s ratio is maximized by the highly different mechanical properties of the two domains. Using the omni-directionally stretchable film, a stretchable display that exhibits regular expansion during stretching, namely the distortion-free stretchable display is fabricated. In addition, the omni-directionally stretchable film with tailored negative Poisson’s ratio to fit the human skin is utilized for human-machine interface. Consequently, the various utilizations of the glass-fabric reinforced film from foldable to stretchable electronics are suggested and proven in this study.