Soluble polyfunctional vinyl aromatic polymer and method of producing the same

A method of producing a soluble polyfunctional vinyl aromatic polymer having a controlled molecular weight distribution, comprising performing cationic polymerization of a monomer component containing 20 to 100 mol % of a divinyl aromatic compound (a) at a temperature of 20 to 120° C. in an organic solvent in the presence of a donor component selected from the group consisting of a quaternary ammonium salt, an ether-based compound having 3 or more carbon atoms, a thioether-based compound having 3 or more carbon atoms, and a sulfoxide-based compound having 2 or more carbon atoms with a Lewis acid catalyst and an initiator represented by the following general formula (1):

• wherein R1 represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, R2 represents an aromatic hydrocarbon group or aliphatic hydrocarbon group of p-valence, Z represents a halogen atom, or an alkoxy group or acyloxy group having 1 to 6 carbon atoms, p represents an integer of 1 to 6, and when a plurality of R1 and Z are present in a molecule, R1 and Z may be identical to or different from each other.