Mechanical reinforcement of UV-curable polymer nanocomposite for nanopatterned mold

This study proposed a method for manufacturing nanopatterned molds with high strength and durability using UV-curable polymer nanocomposites. Zirconia (ZrO2) nanoparticles (NPs) were blended with Ormostamp, a commercial UV-curable resin, using the solution blending method. The elastic modulus and hardness of the cured nanocomposite layer were investigated through a nanoindentation test for different volume ratios of NPs in the Ormostamp composite from 0 to 53.8%. The modulus and hardness of pure resin were 0.075 +/- 0.002 GPa and 9.7 +/- 0.164 MPa, respectively, and they increased to 11.9 GPa and 146.9 MPa at an NP concentration of 58.3%. Nanocomposite molds were fabricated by nanoimprinting with a PDMS stamp, which is replicated from the nanodimple array master. The fabricated nanocomposite mold can efficiently replicate other UV-curable resins. Hot embossing was then performed for a PMMA film using the fabricated molds. Unlike a pure UV-curable resin, which showed damage and fracture of the dimple structure after the first replication, the nanocomposites maintained the nanodimple shape even up to 30 replications. Uniform nanopatterns can be formed on even cylindrical surfaces by using a soft replica stamp. Polymer nanocomposites with a high NP concentration exhibited significantly improved mechanical reinforcement when compared to conventional pure polymers for mold making. Therefore, they are expected to be extremely useful for manufacturing nanopatterned molds using UV resin.