Investigation of monomer reactivity, polymer microstructure and solubility in the copolymerization of 1,5-dioxepan-2-one with alkyl substituted lactones

[Display omitted] •Copolymerization of 1,5-dioxepan-2-one (DXP) with the alkyl substituted lactones.•Determination of copolymerization ratios and microstructure.•Favorable copolymerization ratios for 1,5-dioxepan-2-one with δ-undecalactone.•Poly(1,5-dioxepan-2-one) solubility properties can be tuned with δ-undecalactone. Ring Opening Polymerization of lactones is an excellent synthetic tool for the production of polyesters with tuned microstructure. In copolyesters, the polymer microstructure is an important feature that can greatly influence the properties. Therefore, it is desirable to investigate the copolymerization behaviour of monomers. In this work, the copolymerization of 1,5-dioxepan-2-one (DXP) with the potentially renewable alkyl substituted lactones δ-undecalactone (UDL) and β,δ-trimethyl-ε-caprolactone (TMCL) was investigated. The reactivity ratios were determined for both monomer pairs, and revealed that both substituted lactones react significantly different with DXP. Furthermore, the microstructure of copolymers from DXP and UDL with different monomer feed ratios was characterized by quantitative 13C NMR and MALDI-ToF MS analysis. The resulting copolymers exhibited a varying degree of randomness depending on the monomer feed ratio. The lactones in this study were selected for their different solubility properties. The Hansen solubility spheres were determined for the homo-and copolymers of DXP and UDL. Using this, we demonstrated that the polymer solubility properties can be tuned by copolymerization of polar and apolar monomers.