Thioester-Containing Photoresins for Vat Photopolymerisation: Thiol–Thioester Exchange, Controlled Degradation, Filler Recovery, Oligomer Reuse and Qualification

Thioester-containing photoresins combine rapid radical cure with post-cure bond exchange. Direct evidence includes masked stereolithography of anhydride-derived reversible thioester networks, SLA composites that degraded with 91% filler recovery, and tough semicrystalline resins that were converted into thiol-functional oligomers and repolymerised into stiff or soft objects. Earlier thiol-X photopolymers established recovery and repolymerisation chemistry but did not by itself qualify a VPP process. The mechanisms are not interchangeable: thiol–thioester transesterification requires a thiolate/nucleophile and retains a thioester, whereas anhydride-derived thioesters can participate in a temperature-dependent network equilibrium. Dissolution is not automatically monomer recovery, and matching modulus does not close a recycling loop. ER-112 therefore couples molecular identity, vat optics, cure, catalyst state, service creep, input-output mass, recovered-species analysis, reprint process windows and cycle-dependent performance.

3Dresyns Engineering Review ER-112, version 0.2. Provider-neutral technical review. The deposited PDF is controlled by its exact SHA-256 in the release manifest.