We prepared an amphiphilic, comb-like poly(oxyethylene) containing decyl-tri(oxyethylene) amphiphiles in the side chain using a polymer analogous reaction to obtain a novel nonionic amphiphilic polymeric system with, high molecular weight. The amphiphilic comb-like poly(oxyethylene) itself only showed a side-chain crystalline, phase below its melting temperature of -31 degreesC. When the polymer was mixed with lithium perchlorate, a smectic liquid-crystalline phase appeared. The ordered phases of the,polymer,and the polymer mixture were studied by differential scanning calorimetry, polarized optical microscopy, and X-ray diffraction.