Low-Friction and Lubricious Surfaces on Printed Photopolymers: Additives, Grafts, Coatings, Migration and Wear

Low friction on a printed photopolymer is not an intrinsic material property. It is the response of a complete tribosystem comprising the printed and post-cured resin, the location and attachment of the lubricating function, the counterface, contact geometry, load, speed, motion, temperature, environment and accumulated sliding history. Bulk solid lubricants, surface-segregated additives, covalently attached brushes, deposited coatings and hydrated layers can all reduce friction, but they replenish, migrate, wear and fail by different mechanisms. This review defines a qualification architecture for low-friction and lubricious printed-photopolymer surfaces. It separates initial friction from durable lubricity; requires friction and wear to be paired with surface and counterface evidence; treats migration, blooming, leaching, transfer-film formation, coating loss and substrate exposure as time-dependent state changes; and preserves the distinction among dry, oil-lubricated and aqueous contacts. Direct evidence from photocurable vat-polymerisation composites is combined with bounded adjacent evidence from UV-cured coatings, grafted polymer brushes, hydrogel coatings and UV-cured thin films. The result is a non-compensatory framework for qualifying the intended tribosystem. No commercial formulation, universal additive loading, coating thickness, coefficient of friction, wear rate or service lifetime is established.