Mechanically robust, transparent, and high-κ UV-curable copolymer for nanoimprint microcups and fast response electrophoretic display

Electrophoretic displays (EPDs), recognized 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. Here, we report a UV-curable copolymer system through the copolymerization of polyurethane acrylate (PUA) with methyl methacrylate (MMA), with the aim of enhancing the dielectric properties of the microcup layer and thereby improving EPD response performance. After systematic optimization, the PUA-15%MMA copolymer film demonstrates a well-balanced profile of properties compared to pure PUA, 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, exhibiting excellent dimensional stability 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. Combined with an appropriate e-ink, 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.