Effect of a cross-linking agent on the synthesis and colloidal properties of poly(N-isopropylmethacrylamide) microgel latexes

Microgel latex particles were prepared by batch precipitation polymerizatio n of N-isopropylmethacrylamide (NIPMAM) monomer, using methylenebisacrylami de (MBA) and potassium persulfate (KPS) as a crosslinker and initiator resp ectively. Polymerization kinetics and final particle size as measured by qu asi-elastic light scattering (QELS) at 20 degrees C was not affected upon v arying the cross-linker concentration. In contrast, the final particle size determined using both QELS (at 50 degrees C) and SEM exhibits an increased in particle diameter upon increasing the MBA concentration. In addition, t he amount of water soluble polymer was found to be directly related to the amount of MBA. Finally, the electrophoretic mobility behavior of the obtain ed latexes were investigated as a function of temperature.