Determination of Lower Critical Solution Temperature of thermosensitive flocculants

Thermosensitive polymers are gaining increasing interest due to their possible applications as drug delivery systems, flotation agents in mineral ore processing or flocculants in wastewater treatment. Lower Critical Solution Temperature (LCST) is a crucial parameter of thermoresponsive polymers. In this work the comparison of four different methods of LCST determination, i.e. transmittance, viscosimetric, Dynamic Light Scattering (DLS) and pH measurement, are presented. They are found to be complementary and each of them is shown to fail under certain condition. For the purpose of this research a cationic copolymer of poly(N-isopropylacrylamide) with diallyldimethylammonium chloride was synthesized. Moreover two reference polymer samples were investigated.