Induction heating of dual magnetic particles embedded PDMS molds for roller embossing applications

Roller embossing is an effective manufacturing process for replicating microstructures onto polymeric substrates, featuring high-volume production, rapid manufacturing, and large-area processing. Polydimethylsiloxane (PDMS) is a cost-effective mold material that is easy to replicate, but its easy deformability may cause mold distortion under a high roller embossing pressure. Furthermore, PDMS is not an effective induction heating mold because of its high thermal resistance and poor conductivity. Therefore, this research confronted the three main challenges of PDMS: low hardness, poor thermal conductivity, and heating inefficiency. We proposed a PDMS mold embedded with dual magnetic particles (DMP-PDMS), which can improve the hardness and thermal conductivity of PDMS and be directly heated by induction heating. This study designed and constructed a roll-embossing apparatus to fabricate polymer microlens arrays using DMP-PDMS composite molds. It is the first study to use dual magnetic particles embedded in PDMS for direct induction heating and generate an internal heat source to 220 °C within 60 s. Compared with a single type of magnetic particle embedded in PDMS, the heating efficiency is increased by 134%. This study demonstrates the feasibility and potential of induction heating DMP-PDMS molds for rolling embossing instead of replicating microstructures with metal molds.