Continuous flow rare earth phenolates catalyzed chemoselective ring-opening polymerization

•Continuous flow rare earth phenolates catalyzed chemoselective ring-opening polymerization.•Systematical study on the effect of microscale effect on polymerizations.•Faster polymerizations, higher chemoselectivity, more controlled molecular weight and distribution in microreactor.•High efficient flow synthesis of well-defined thiol-terminated poly(ε-caprolactone)s.