Photobase-Mediated and Base-Catalysed Photocuring in Vat Photopolymerisation: Generator Release, Michael-Addition Networks, Ring-Opening Routes, Anionic Boundaries and Latency Qualification
Segurola, Juan
2026-09-14 · Report · Version 0.3
Photobase generators provide spatial and temporal control over the release of organic bases or nucleophiles, enabling non-radical and hybrid routes for light-based polymer formation [1,2]. Visible-light thiol-Michael systems have used tetraphenylborate salts, coumarin and o-nitrobenzyl photocages, photocaged phosphines and BODIPY chromophores to release amidines, guanidines or nucleophilic phosphines [3–9]. A recent ionic-liquid resin demonstrated commercial- DLP printing of a photobase-catalysed thiol-Michael ionogel with 250 µm features and a three-hour dark-stability window under the reported rheological test [11]. Lewis-photobase and phosphazene-superbase studies extend the architecture to oxa-Michael reactions and hot lithography, but also expose the latency problem: elevated temperature or premature base release can drive unintended acrylamide homopolymerisation [12,13]. Photobases also trigger polyurethane formation and ring-opening polymerisation of lactide and amino-acid N-carboxyanhydrides [10,14,15]. Photobase-catalysed thiol-epoxy polymerisation and a direct living anionic ring-opening study define the boundary between catalytic anionic click chemistry and persistent chain-carrying propagation [18–20]. Base amplification can deliberately extend conversion after irradiation, so efficient dark cure is not equivalent to acceptable shelf stability [8]. This review separates base-catalysed step growth, nucleophile-catalysed addition, ring-opening polymerisation and true anionic chain growth; defines pathway-specific failure modes; and proposes a minimum qualification architecture for generator release, intended conversion, radical-side-reaction fraction, dark cure, ageing and final performance. No universal inhibitor, generator or additive dose is proposed.