Mechanically Robust, Transparent and High-κ UV-curable Copolymer for Nanoimprint Microcups and Fast Response Electrophoretic Display

Electrophoretic displays (EPDs), known for their low power consumption and portability, offer a viable alternative to plain paper. However, their adoption in high-frame-rate applications has been limited by slow response times. To address this, an UV-curable material by copolymerizing polyurethane acrylate (PUA) with methyl methacrylate (MMA) is developed for the use of fast response EPD. After systematic optimization, the PUA-15%MMA copolymer film exhibits more desirable overall properties as compared with pure PUA film, including considerable optical properties, enhanced mechanical strength (32.9 MPa vs 18.7 MPa), strengthened modulus (660.7 MPa vs 330.4 MPa) and particularly the raised dielectric constant (7.4 vs 4.2, at 1 kHz). It is inspiring to find that this optimized film enables a rapid electro-optical response, achieving an 800 ms white-black state switching time at 30 V. To verify the applicability, this copolymer film is processed into precise microcup arrays using nanoimprinting technique, showing outstanding dimensional accuracy and solvent resistance. The corresponding microcups are also utilized for the assembly of a EPD device, successfully allowing the display of the university logo after being driven. This UV-curable, mechanically robust, transparent and high-κ copolymer film is expected to be used as a promising candidate for durable and fast response EPDs.