ABA-type triblock copolymers and AB-type star diblock copolymers with poly(2-adamantyl vinyl ether) [poly(2-AdVE)] hard outer segments and poly(n-butyl vinyl ether) [poly(NBVE)] soft inner segments were synthesized by sequential living cationic copolymerization. Although both the two polymer segments were composed solely of poly(vinyl ether) backbones and hydrocarbon side chains, they were segregated into microphase-separated structure, so that the block copolymers formed thermoplastic elastomers. Both the ABA-type triblock copolymers and the AB-type star diblock copolymers exhibited rubber elasticity over wide temperature range. For example, the ABA-type triblock copolymers showed rubber elasticity from about 53 degrees C to about 165 degrees C and the AB-type star diblock copolymer did from about 47 degrees C to 183 degrees C with a similar composition of poly(2-AdVE) and poly(NBVE) segments in the dynamic mechanical analysis. The AB-type star diblock copolymers exhibited higher tensile strength and elongation at break than the ABA-type triblock copolymers. The thermal decomposition temperatures of both the block copolymers were as high as 321331 degrees C, indicating their high thermal stability. (c) 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013, 51, 1796-1807