Cationic polymerization of p‐methylstyrene initiated by acetyl perchlorate: An approach to living polymerization

Publisher Website
Google Scholar
Abstract
The cationic polymerization of p‐methylstyrene initiated by acetyl perchlorate at −78°C led to long‐lived (living‐like) polymers with a narrow molecular weight distribution (M̄w/M̄n = 1.1–1.4) in methylene chloride containing a common ion salt (n‐Bu4NClO4) or in a less polar solvent (CH2Cl2/toluene, 1/4v/v). Under these conditions, the number‐average molecular weight (M̄n) of the polymers increased in proportion to monomer conversion and was regulated by the monomer‐to‐initiator ratio. When fresh feeds of the monomer were repeatedly added to a completely polymerized solution, the polymerization ensued at the same rate as before and the linear increase in M̄n with monomer conversion continued. The effects of solvent polarity and the common ion salt on the polymerization showed the suppression of the ionic dissociation of the propagating species, resulting in a “nondissociated species,” to be the key factor for the formation of the long‐lived polymers.