A double-sided PDMS mold for double-sided embossing by rollers

Polydimethylsiloxane (PDMS) is a polymer that is both elastic and cost-effective, making it an ideal material for replication molds when creating delicate microstructures. Its surface microstructure is durable, and the replication process is straightforward and fast. However, as the mold is soft, no extensive research has been conducted to prove it is suitable for rolling embossing. Moreover, PDMS is an insulator with high thermal resistance, making it difficult to heat uniformly for embossing. Typically, external heat sources are used to heat PDMS molds indirectly. We developed a double-sided mold with magnetic powder embedded inside PDMS to overcome these challenges and increase hardness and heating efficiency. Our study addresses the air-gap issue when roller embossing convex microlens arrays on polymethylmethacrylate (PMMA) polymer. Ultimately, this research also realized a double-sided PDMS mold for simultaneous double-sided embossing of two pieces of PMMA convex and concave microlens arrays on a roller, improving the microstructure's replication fidelity.