(n-Hexadecylsulfonyl)methyl-substituted poly(oxyethylene) (16SP), (n-hexadecylthio)methyl-substituted poly (oxyethylene) (16TP), [(6-n-nonyl sulfonyl)hexylthiol methyl-substituted poly(oxyethylene) (9S6TP), and [(6-n-nonyisulfonyl)hexylsulfonyllmethyl-substituted poly(oxyethylene) (9S6SP) were synthesized. 9S6SP and 16SP containing sulfonylmethyl side groups showed highly ordered smectic layer structures at room temperature and liquid crystalline behavior at higher temperatures, while 9S6TP and 16TP containing thiomethyl side groups did not show any liquid crystalline behavior. The ordered phases of the polymers were studied using differential scanning calorimetry, cross-polarizing optical microscopy, and X-ray diffraction. The unusual liquid crystallinity of 16SP and 9S6SP was ascribed to the amphiphilic character of these polymers.