A new, highly stable cationic-thermosensitive microgel: Uniform isopropylacrylamide-dimethylaminopropylmethacrylamide copolymer particles

Eke I., Elmas B., Tuncel M., Tuncel A.

COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, vol.279, pp.247-253, 2006 (SCI-Expanded) identifier identifier


New monodisperse, thermosensitive, cationic microgel particles up to 1930 +/- 56 nm in size were obtained by the dispersion copolymerization of N-isopropylacrylamide (NIPA) and N-3-dimethyl-aminopropylmethacrylamide (DMAPM). In the developed protocol, an amide based comonomer. DMAPM was tried as a new alternative material for introducing positive charge to the thermosensitive microgel. Poly(NIPA-co-DMAPM) microgel exhibited pH-sensitivity and the particle size linearly decreased with increasing pH. Poly(NIPA-co-DMAPM) microgel synthesized without making any pH adjustment in the aqueous medium exhibited colloidal stability between pHs 3 and 10 while similar cationic microgels were reported to be unstable at pHs higher than 6. The stronger cationic character of selected comonomer originated from its amide based structure (i.e. higher pK(a) of DMAPM) provided higher colloidal stability to the poly(NIPA-co-DMAPM) microgel.