Double Replication of Silica Colloidal Crystal Films

Inverse opals made by polymerizing vinyl monomers inside a colloidal crystal have lattice dimensions that are contracted relative to the original hard template. This effect was studied in order to investigate the possibility of making double replicas of varying pore sizes from different materials, and to gain a better understanding of the polymer contraction behavior during replication. The degree of lattice contraction was measured using colloidal crystal films formed from silica spheres with diameters in the range 33–225 nm, and polymers pEDMA [poly(1,2-ethanediol dimethacrylate)], pDVB [poly(divinylbenzene)], pHDMA [poly(1,6-hexanediol dimethacrylate)], pBDMA [poly(1,4-butanediol dimethacrylate)], and a 5:4 copolymer mixture of pEDMA/pDVB. The degree of lattice contraction depended on the alkyl chain length of the monomer, as well as the degree of cross-linking, with up to 32% contraction observed for pEDMA when the silica template was removed. However, filling the polymer inverse opals with silica or ...