The effects of solvent and initiator on anionic ring opening polymerization of ε-caprolactone: Synthesis and characterization

Abstract

Anionic ring opening polymerization of ε{lunate}-caprolactone was studied by using different amounts of two potassium activated initiators containing ethylene glycol (EG) and polyhedral oligomeric silsesquioxane (POSS) diol, in tetrahydrofuran and toluene as solvents. The synthesized hydroxyl terminated macromers and linear poly(ε{lunate}-caprolactone) (PCL) were characterized by proton and carbon nuclear magnetic resonance and gel permeation chromatography (GPC) techniques. Results showed an increase in molecular weight as the monomer/initiator molar ratio increased from 100 to 151 and 202, while the molecular weight distribution (MWD) showed a minimum by monomer concentration increase. Moreover, POSS-diol-initiated PCLs showed a higher MWD than the polymers initiated with the EG initiator. This was attributed to the formation of a vesicular structure of POSS diols which was confirmed by optical microscopy. By deconvolution of GPC peaks, the best conditions to synthesize PCL with the narrowest MWD were selected. Finally, the effects of some other parameters were studied in more detail. AROP of ε{lunate}-CL, using POSS diol as initiator in THF and toluene media was performed. Polymerization mechanism was fully discussed and compared with one, initiated by a small EG molecule. © 2013 Society of Chemical Industry.