Highly efficient synthesis of heteroarm star-shaped polymers using polymer-linking reaction and their characteristic stimuli-responsive behaviors

Heteroarm star-shaped polymers containing independent stimuli-responsive moieties were synthesized by a one-pot arm-linking reaction based on base-assisting living cationic polymerization. Mixing two or more kinds of living polymers followed by the linking reaction with a divinyl compound successfully produced a heteroarm star-shaped polymer containing a number of arm chains with a narrow molecular weight distribution (M w /M n 1.14-1.48) and high yield. For example, four kinds of linear poly(vinyl ether)s containing oxyethylene and alicyclic pendants were linked quantitatively to give a star polymer without any deactivation of the starting polymers. The heteroarm star-shaped polymers exhibited their unique stimuli-responsive behaviors in water or their film surfaces. Furthermore, linear living poly(2-methoxyethyl vinyl ether) and poly(2-phthalimidoethyl vinyl ether) were linked efficiently despite their different reactivities, producing a heteroarm star-shaped polymer with amino-containing and thermosensitive arms. The obtained star polymer exhibited unique aggregation behaviors in response to both pH and temperature in water. This report demonstrates that this one-pot arm-linking reaction is a facile and effective methodology for synthesis of heteroarm star polymers with various combinations of stimuli-responsive arm chains.