The temperature-induced conformational transitions of neutral poly(N-isopro
pylacrylamide) chains at interfaces are studied in the presence of a surfac
tant, sodium dodecyl sulfate in an aqueous solution. The results obtained f
rom the collapse-to-swelling transition show that the polymer dimension in
good solvency is smaller after collapse transition than that before the tra
nsition. Such a dimension difference due to the conformational changes beco
mes significant with increasing the surfactant concentration and final coll
apse temperature. The polymer-surfactant complexes, the ion pair, and the m
ultiplet structure are believed to play roles in inducing the entanglement
of interfacial chains in the poor solvency domain.