Synthesis and Characterization of Functional Mesostructures Using Colloidal Crystal Templating
Abstract
Functional 3-D periodic mesostructures were synthesized via colloidal crystal templating, and their chemical, physical, and optical properties were characterized. By forming colloidal crystals through self-organization, infiltrating the interstitial space with functional materials, and then removing the templates by chemical etching, inverse opal mesostructures with characteristic distances on the order of optical wavelengths were generated from conducting polymers, hydrogels, and metals. These active mesostructures allow tuning of properties such as Bragg diffraction, potentially enabling applications as electrochemical elements, sensors, flow control devices, and novel photonic band gap materials. Inverse opal conducting polymer films were fabricated by electropolymerization.The templated films exhibited a compact morphology and larger electrochemical response from cyclic voltammetry. They also displayed shifts in Bragg diffraction, possibly due to changes in interchain spacing and refractive index during redox cycling. Inverse opal hydrogels were templated using free radical photopolymerization. By copolymerizing appropriate functional groups, mechanically robust thin films were synthesized that exhibit reversible shifts in Bragg diffraction based on changes in solvent, PH, ionic strength, crosslink density, and glucose concentration, caused by the expansion and contraction of the hydrogel film due to changes in the local chemical potential. The kinetics of the diffraction response was also studied and found to be diffusion limited. The diffraction response of the inverse opal hydrogels were correlated to the deformations of their mesostructure directly observed using multiphoton fluorescence microscopy. Reconstruction of the pore mesostructure revealed that the hydrogel swelled primarily in the sample normal direction, with a significant shrinkage and deformation of the face centered cubic pores, consistent with predictions from scalar wave approximation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2004
- Accession Number
- AD1020750
Entities
People
- Yun-ju Lee
Organizations
- University of Illinois Urbana–Champaign