Microgel particles as model colloids: theory, properties and applications

This review presents an overview of the literature concerning microgel particles with emphasis on work performed during the past 5 years. Microgel particles are cross-linked latex particles that are swollen in a good solvent. The particles are conveniently prepared by surfactant-free emulsion polymerisation (SFEP) and may be viewed as sterically stabilised particles without a core. The narrow particle size distribution combined with the inherent steric stabilisation of particles prepared by SFEP makes them ideal model systems for the study of solution-dependent phenomena (e.g. osmotic de-swelling). The poly(NIPAM) (NIPAM=N-isopropylacrylamide) microgel system is considered in detail in terms of swelling, rheological, small-angle neutron scattering (SANS) and kinetic data. The review concludes with a discussion of the internal structure for microgel particles and consideration of areas for further research.