Poly(2-hydroxyethyl methacrylate-b-styrene-b-2-hydroxyethyl methacrylate) triblock copolymer was synthesized by hydrolysis of poly(2[(trimethylsilyl)oxy]ethyl methacrylate-b-styrene-b-2[(trimethylsilyl)oxy]ethyl methacrylate) triblock copolymer polymerised with or-methylstyrene tetramer disodium as an initiator by an anionic living polymerisation technique. Micelle formation of the poly(2-hydroxyethyl methacrylate-b-styrene-b-2-hydroxyethyl methacrylate) triblock copolymer was investigated in dimethylformamide (DMF), toluene, cyclohexane and a toluene/n-hexane mixture by dynamic light scattering (DLS) method. Monodispersed polymer micelle with a poly(2-hydroxyethyl methacrylate) core and polystyrene shell chains was formed with the triblock copolymer in a toluene and n-hexane mixture when n-hexane was 62 vol%. The poly(2-hydroxylethyl methacrylate) core was crosslinked with 1,6-hexanediisocyanate. Crosslinked products were spherical and their diameters were measured in the toluene by the DLS method. Additionally, microgel with free end shell chains was synthesized as the reference of the microgels with loop shell chains by scission of the loop shell chains at their centre by exposure to ultraviolet light.