Preparation of thermosensitive latexes by copolymerization of N-isopropylmethacrylamide with a chelating monomer

Functional poly(N-isopropylmethacrylamide) (NIPMAM) copolymer latexes were prepared at 80 degrees C using methylene-bisacrylamide (MBA) as the crossli nking agent, and potassium persulfate (KPS) as the initiator in the presenc e of N-(vinylbenzylimino)-diacetic acid (IDA). Adding functional monomer (I DA) was found to drastically affect particle size, but not size distributio n as observed both by scanning electron microscopy and quasi elastic light scattering. However, performing the polymerization reaction at too high fun ctional monomer concentration, led to enhanced the formation of water solub le polymers (WSP). The Lowest Critical Solubility Temperature (LCST) of cle aned latexes was measured by a turbidimetric method reflecting the thermose nsitive behavior of the particles. The transition temperature was found to be around 43 degrees C, and was only slightly dependent on the concentratio n of functional monomer.