Microgels for Controlled Uptake and Release

Abstract

It has been estimated that 10 m people die each year from drinking contaminated water [1]. Contaminants include heavy metal ions, such a Pb(11) and Cd(11) (principally from sewage waste), fertilisers, pesticides and surfactants (from detergents and other household and personal cleaning products). Many options for their removal are available, including the use of such materials as activated carbon and ion-exchange resins [2]. Colloidal microgel particles offer a novel, alternative method for water purification. Microgel particles are essentially cross-linked, polymer latex particles, which swell in a good solvent environment for the polymer concerned [3]. The degree of swelling is controlled by the extent of cross-linking. These types of particles may be prepared by conventional latex polymerisation routes, such as dispersion or inverse-microemulsion polymerisation. The cross-linking is achieved by the use of low levels of a bifunctional co-monomer. The main feature which makes microgel particles suitable for the absorption of species for aqueous media is the facility to build-in ”binding” groups into the interior of the particles, which associate with the species to be removed. This is often achieved by copolymerising, with the matrix monomer, an additional monomer having the required functionality. In this paper the potential use of microgel particles as water clean-up agents will be illustrated by three specific examples.