Meso-structured (opal and inverse opal) polymeric hydrogels of varied morphology and composition wereprepared by using two methods: post-modification of the template-synthesized structured polymers and template-polymerization of functional monomers. A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fastpH response by changing color, which is important in designing tunable photonic crystals. Template effects of the hydrogelson controlling structure of the template-synthesized inorganic materials were discussed. The catalytic effect of acid groups inthe templates was emphasized for a preferential formation of TiO_2 in the region containing acid groups, which allowedduplicating inorganic colloidal crytals from colloidal crystal hydrogels (or macroporous products from macroporoushydrogels) via one step duplication. Meso-structured (opal and inverse opal) polymeric hydrogels of varied morphology and composition wereprepared by using two methods: post-modification of the template-synthesized structured polymers and template-polymerization of functional monomers. A polyacrylic acid based inverse opal hydrogel was chosen to demonstrate its fastpH response by changing color, which is important in designing tunable photonic crystals. which are important in designing tunable photonic crystals. Template effects of the hydrogelson controlling structure of the template-synthesized inorganic materials were discussed. The catalytic effect of acid groups inthe templates was emphasized for a preferential formation of TiO 2 in the region containing acid groups, which allowedduplicating inorganic colloidal crytals from colloidal crystal hydrogels (or macroporous products from macroporoushydrogels) via one step duplication.