Polystyrene and polystyrene‐butadiene latexes stabilized by poly(N‐isopropylacrylamide)

Latexes stabilized by poly(N‐isopropylacrylamide) (polyNIPAM) were prepared by polymerizing NIPAM in the presence of polystyrene and polystyrene‐butadiene latex or by styrene emulsion polymerization in the presence of NIPAM. In 0.01 M CaCl2 polyNIPAM stabilized latexes exhibited critical flocculation temperatures in the range 32–35°C, which is approximately equal to the lower critical solution temperature of polyNIPAM in water. Partial substitution of NIPAM with some acrylamide (AM) gave higher flocculation temperatures. Coagulation studies with cleaned latex indicated that the polyNIPAM or polyNIPAM‐co‐AM polymer chains were anchored to the latex particle surfaces.