Surface Active Properties and LCST Behavior of Oligo(propylene oxide-block- ethylene oxide) Allyl Ether Siloxane Surfactants in Aqueous Solution

Department of Chemical Engineering, Hanyang University, Ansan 425-791, KoreaReceived December 6, 2003Polydisperse oligo(PO-b-EO) allyl ether siloxane surfactants were synthesized by the hydrosilylation reactionof OMTS with Allyl-oligo(PO-b-EO) series. The surface tension of siloxane surfactants increased withincreasing the EO chain length while it decreased with increasing the PO ratio. However, the sedimentationtime of the aqueous solution showed opposite trend to the surface tension data. Both the surface tension andsedimentation time of the aqueous solution containing inorganic electrolyte gradually decreased as the contentof inorganic electrolyte increased because of the surface arrangement of surfactant molecules. However, theyincreased with an increase of pH values due to the hydrolysis of the siloxane backbone. The C