A new family of thermo-, pH-, and CO2-responsive homopolymers of poly[oligo(ethylene glycol)(N-dialkylamino)-methacrylate]s combining the pendants of oligo ethylene glycol (OEG) moiety and dialkylamine are synthesized by RAFT polymerization. In these poly[oligo(ethylene glycol) (N-dialkylamino) methacrylate]s, the OEG moiety as well as the dialkylamine group affords thermoresponse, and the dialkylamine group affords pH-, and CO2-response. The phase transition temperature (CP) of poly[oligo(ethylene glycol) (N-dialkylamino) methacrylate]s is firmly correlative to the number of the OEG moiety and the dialkylamine group, and it is found that higher number of the OEG moiety and higher CP, and the longer dialkylamine group and the lower CP, respectively. By tuning the OEG moiety and the dialkylamine group, eight thermo-, pH-, and CO2-responsive homopolymers with CPs ranging from 7 to 79 degrees C are synthesized. The thermoresponsive phase transition of poly[oligo(ethylene glycol) (N-dialkylamino) methacrylate]s is investigated by temperature -variable H-1 NMR analysis, and the parameters affecting thermoresponsive phase transition of poly[oligo(ethylene glycol) (N-dialkylamino) methacrylate]s including polymerization degree, polymer concentration, terminals attached to the polymer backbone, salt, and urea are investigated. Multithermoresponsive diblock copolymer and triblock copolymer exhibiting two and three CPs are synthesized, and their versatile micellization upon temperature changing is demonstrated.