The invention provides a method of efficiently producing branched, cyclic glycerol-based polyols with a co-product as anti-biodegrading agent from inexpensive readily available glycerol monomer. The method involves polymerizing glycerol or glycerol with at least another monomer to multiple other monomers in the presence of particular amount of a strong base as the catalyst under a particular distillation environment. The polyol produced by the inventive method is beneficial of reducing scales in Bayer liquid for aluminum production process and improving brightness of coated paper substrates without greening effect.