Smart Microgel Particles with Tuneable Responses: Synthesis, Properties and Application of Well- Defined Core-Shell Microgels

Colloidal microgels that are able to alter their volume and properties in response to environmental stimuli are attractive materials for various applications. However, current methods to prepare microgels that possess both pH- and temperature- sensitive properties still suffer from two major drawbacks: 1) Limit to the use of pH-sensitive vinylic monomer. Thus, many pH-sensitive polymers like bio- and synthetic polymers cannot be used. 2) Phase transition temperature of the polymer is influenced by protonation degree of the pH-sensitive polymer. In this book, a novel method to prepare smart microgels that consist of well-defined temperature-sensitive cores with pH-sensitive shells is described in details. The microgels are synthesized directly from aqueous graft copolymerization of N-isopropylacrylamide or N- vinylcaprolactam with a crosslinker, from water- soluble polymer of poly(ethyleneimine) or chitosan. The well-defined core-shell nanostructure exhibits tuneable responses to pH, temperature and electrolyte changes. Thus, this new type of smart materials should be extremely useful in drug delivery, biosensing, separation technology, etc.