Synthesis and characterization of novel pH-responsive polyampholyte microgels

We synthesized for the first time novel pH-responsive polyampholyte microgels consisting, of poly(methacrylic acid) and poly(2-(diethylamino)ethyl methacrylate) (PMAA-PDEA) that are sterically stabilized with poly(ethylene glycol) methyl ether methacrylate (PEGMEM). These microgels showed enhanced hydrophilic behavior in aqueous medium at low and high pH but become hydrophobic and compact between pH 4 and 6 near the isoelectric point, Dynamic-light scattering measurements showed that the hydrodynamic radius, R-h of these microgels is approximately 100 nm between pH 4 and 6 and increases to around 140 and 170 run at pH 2 and 10, respectively. It is evident that the cross-linked MAA-DEA microgel that is sterically stabilized with PEGMEM retains the polyampholyte properties in solution.