The nonionic surfmer AREO7 was first used in the ultrasonically irradiated emulsion polymerization of styrene. The added AREO7 could improve the emulsion solid content. Through FTIR, GC-MS, and DSC studies, it was found that the polymer produced was the copolymer of styrene and AREO7. The copolymer latics polymerized in proper conditions displayed nanoparticles. When AREO7 concentration increased, there were more nanostructured copolymer gels, in which AREO7 molecules form an aniphiphilic network, whereas polystyrene was located in hydrophobic droplet. The latics had a structured morphology that the AREO7 units were mainly on the surface of particles. The glass transition temperature (T-g) of copolymers decreased with the increase of AREO7 composition in copolymers. Freeze-thaw test showed that the freeze-thaw stability of the copolymer emulsion was improved greatly because of the increasing composition of AREO7 in copolymers. (C) 2004 Wiley Periodicals, Inc.