Release layer-free acrylate resins with segregation auxiliary agents for ultraviolet nanoimprinting

Abstract

The authors prepared ultraviolet (UV)-cured resin films with glycerin 1,3-dimethacrylate (GDM), modified by the addition of reactive fluoroalkyl acrylates. The authors then measured the decrease in the surface free energy of these materials to investigate their potential for successful demolding in UV nanoimprinting with unmodified silica molds. The fluoroalkyl acrylates of CHF2-terminus hexadecafluoro-1,1,9-trihydrononyl acrylate (16F-AC) and octafluoro-1,1,5-trihydropentyl acrylate (8F-AC) and CF3-terminus heptafluoro-1,1,2,2-tetrahydrodecyl acrylate (17F-AC) were used. The addition of 16F-AC, with its fluorinated long alkyl chain, to GDM effectively decreased the surface free energies, in comparison with 8F-AC. The solubility of 17F-AC in GDM improved in the presence of the 16F-AC and 8F-AC. As a result, the cured resin films made with the ternary monomers of GDM, 17F-AC, and 16F-AC or 8F-AC showed low surface free energies at small fluorine atomic percentages in comparison with the cured resin films made with the binary monomers of GDM and 17F-AC, 16F-AC, or 8F-AC. X-ray photoelectron spectroscopy showed that the decrease in surface free energy in the ternary monomer system can be attributed to the effective surface segregation of the fluorinated alkyl moieties because of co-assembly of the fluoroalkyl acrylates. 16F-AC and 8F-AC function as surface segregation auxiliary agents for 17F-AC. Although it was difficult to perform repeated UV nanoimprinting in air, the ternary UV-curable resin with 17F-AC resulting in a low surface energy allowed step-and-repeat UV nanoimprinting using bare silica molds in a 1,1,1,3,3-petafluoropropane atmosphere.