| Abstract: | The polymerization of 1,3-dioxolane was carried out using trifluoromethanesulfonic acid (triflic acid) as catalyst, in the presence of an oligomeric diol, α-hydro-ω-hydroxypoly(oxyethylene) (PEOG) or α-hydro-ω-hydroxypoly(oxytetramethylene) (poly-THF-diol). When PEOG was used, a linear increase of the number average molecular weight versus conversion was observed. A triblock copolymer was obtained as well as small cycles in their usual equilibrium concentration. When poly-THF-diol was used, fast transacetalization provoked the “polycondensation” of the diol through acetal linkages at the very onset of the reaction, leading to a very inhomogeneous mixture. After equilibrium was reached, through reactions involving all the various species present, a triblock copolymer was also obtained. In conclusion, this method is well suited to prepare α,ω-diol block copolymers in which the initial oligomeric diol constitutes the center block, while the outside blocks are made of polyacetal. |
