Polymerisation-Induced Phase Separation in Vat Photopolymerisation: Kinetic Competition, Morphology Arrest and Functional Microstructure
Segurola, Juan
2026-08-27 · Informe · Versión 1.2
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Vat photopolymerisation normally treats microscopic material homogeneity as a desirable starting condition: reactive components are mixed, exposed and converted into a nominally homogeneous crosslinked network. Polymerisation-induced phase separation reverses this logic. The polymerisation reaction itself can alter thermodynamic compatibility sufficiently to drive demixing while network formation simultaneously restricts diffusion and arrests the emerging morphology. This coupling creates a materials-design mechanism capable of generating polymer-rich and polymer-poor regions, bicontinuous morphologies, dispersed domains, nanoporous or macroporous structures, spatial gradients and functionally segregated phases inside digitally defined three-dimensional objects. Direct DLP and stereolithographic demonstrations now span nanoporous polymers, functional composites, reversible- deactivation-radical-polymerisation systems with nanoscale control, phase-separated polymer alloys, reactive thiol-ene porous structures and porous ceramic or preceramic architectures. The critical engineering variable is not simply whether phase separation occurs. Functional behaviour depends on the competition among polymerisation rate, thermodynamic demixing, molecular diffusion, domain coarsening, gelation, vitrification and optical feedback. Irradiance, exposure history, precursor molecular weight, crosslink density, porogen identity, component ratio and processing temperature can therefore alter morphology even when nominal resin composition is unchanged. This review defines the distinction between polymerisation-induced phase separation, polymerisation-induced microphase separation, pre-existing immiscibility and uncontrolled formulation instability. It develops a qualification framework linking reaction history to domain size, connectivity, optical response, porosity, dimensional fidelity and final mechanical or functional properties. The central conclusion is that PIPS transforms morphology from a passive consequence of formulation incompatibility into an actively engineerable state variable of vat photopolymerisation.