Supporting Data for β-Methyl-δ-valerolactone as a Monomer for UV-Curable and Chemically Recyclable Elastomers

Though the growth of three-dimensional printing (3D printing) by vat photopolymerization has expanded opportunities for polymer manufacturing, most commercial resins are petrochemically-derived and form thermosets that are challenging to recycle. We report the solvent-free synthesis of poly(β-methyl-δ-valerolactone) (PβMVL)-based photocrosslinkable resins from the ring-opening polymerization of the renewable monomer β-methyl-δ-valerolactone (βMVL) with a low ceiling temperature (Tc) in the neat state. We explore the temperature-dependence of the characteristic equilibrium monomer concentration and control the quantities of residual βMVL for sequestration with diamines to give diamidodiols or use as a non-reactive diluent to reduce resin viscosity. We demonstrate the advantage of diamidodiol crosslinkers in the presence of PβMVL to form a bimodal network strengthened with additional hydrogen bonding moieties, resulting in materials with tensile strengths of 8 ± 2 MPa and elongations at break of 105 ± 8 %, which are comparable to commercial vat photopolymerization resins. High resolution 3D-printed materials were produced and shown to be chemically recycled back to βMVL in high yield and purity.