Templating hydrogels

Abstract

Templating processes for creating polymerized hydrogels are reviewed. The use of contact photonic crystals and of non-contact colloidal crystalline arrays as templates are described and applications to chemical sensing and device fabrication are illustrated. Emulsion templating is illustrated in the formation of microporous membranes, and templating on reverse emulsions and double emulsions is described. Templating in solutions of macromolecules and micelles is discussed and then various applications of hydrogel templating on surfactant liquid crystalline mesophases are illustrated, including a nanoscale analogue of colloidal crystalline array templating, except that the bead array in this case is a cubic array of nonionic micelles. The use of particles as templates in making coreshell and hollow microgel beads is described, as is the use of membrane pores as another illustration of confinement templating.

Anion Responsive Imidazolium‐Based Polymers

“…The surface tension data illustrated in Figure 2 suggest the possibility of a sphere to cylinder transition in micelle shape (based on analogies with more classical surfactants) at relatively low concentration (weight fractions ≥ 0.0023). If this gel phase turns out to in fact be a lyotropic liquid crystalline phase, it should yield an interesting new class of zeolites if used to template metal oxide condensation 51, 52. Related triblock copolymers with a much smaller center PPO block (1 kDa) form gel phases at very high weight fraction in water, but no LCSTs have yet been observed for these homologues 53…”

Ionic Liquids and Polymeric Ionic Liquids as Stimuli-Responsive Functional Materials

“…Novel sensors have been derived from such new materials, wherein by one means or another, the analyte causes a change in the effective d-spacing of the particle array, and the reflected or transmitted color changes can be easily quantified using UV/Vis spectrometry. The use of hydrogels as particles in such arrays or as binders gluing such arrays together has been reviewed [77]. Li and co-workers [78] composed such cubic close-packed arrays on PMMA substrate using monodisperse silica nanoparticles about 260 nm in diameter.…”

Hydrogels in Regenerative Medicine

“…These approaches include the use of micellar structures [168] and sacrificial polymer beads [169], or other geometries [8,170] that mimic native tissue architecture. As described previously, one advantage of hydrogel systems is that they provide a matrix comparable in modulus to native extracellular matrix for many soft tissues.…”