Ring-opening homo- and copolymerization of lactones. Part 1. Homo- and copolymerization of racemic β-butyrolactone with ɛ-caprolactone and δ-valerolactone by tetraisobutyldialuminoxane (TIBAO) catalyst

Copolymers of racemic β-butyrolactone (β-BL) with ε-caprolactone (ε-CL) (P(BL-co-CL)) and δ-valerolactone (δ-VL) (P(BL-co-VL)) were prepared by ring-opening polymerization reactions using the commercial aluminoxane catalyst tetraisobutyldialuminoxane (TIBAO). The yields, molecular weights, compositions and crystallinities were determined for both copolymers by gel permeation chromatography (GPC), nuclear magnetic resonance (1H NMR) spectroscopy and differential scanning calorimetry (DSC). A detailed study by 13C NMR spectroscopy has been made to determine monomer diad sequence distributions. These results and those of reactivity ratios indicate that the co-polymers may consist of compatible blocks of BL units and VL units of variable size.