Patent ID: 8536280

Claim:
A star polymer comprising: a core part derived from a coupling agent for anionic polymerization represented by Formula (1): [Chemical Formula 1] P (X—Y—Z) a (1) where P represents an a-valent organic group, a represents 2 to 20, X represents a linking group capable of being cleaved by acid and represented by Formulae (2) to (4): where each of R 1 , R 2 , R 3 and R 4 independently represents a hydrogen atom; or straight chain, branched or cyclic alkyl group or alkoxy group with 1 to 12 carbon atoms capable of being substituted with an alkoxy group, hydroxy group, halogen atom or epoxy group; aryl group or hydroxy group; and R 5 represents a direct bond or straight chain, branched or cyclic alkylene group with 1 to 12 carbon atoms capable of being substituted with an alkoxy group, hydroxy group, halogen atom or epoxy group, or arylene group), Y represents an alkylene group with 1 to 12 carbon atoms or arylene group, and Z represents a halogen atom or epoxy group represented by Formula (6): where each of R 6 , R 7 and R 8 independently represents a hydrogen atom or alkyl group with 1 to 12 carbon atoms; and an arm part having a polymer chain obtained by anionic polymerization, the arm part being attached to the core part.