Influence of reaction conditions on degree of branching in hyperbranched aliphatic polyethers from 3-ethyl-3-(hydroxymethyl)oxetane

The cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetan e to form hyperbranched polyethers has been studied. The polymerizations ha ve been performed in bulk using sulfonium salt initiators. To produce polym ers of different degrees of branching, the reaction conditions (reaction te mperature and initiator) have been varied. Polymerizations have also been p erformed in the presence of a trifunctional core molecule, trimethylolpropa ne. The conversion of monomer turned out to be the main factor determining the degree of branching in the resulting polymer. Polymers with degrees of branching ranging from 0.15 to 0.41 were synthesized. When 3-ethyl-3-(hydro xymethyl)oxetane was polymerized by slow addition of monomer to a core mole cule, a lower degree of branching was obtained compared to the one-step syn thesis with full conversion of monomer. The polydispersity was generally sl ightly lower when a core molecule was used than in the one-step homopolymer ization of 3-ethyl-3(hydroxymethyl)oxetane.