Spiroorthocarbonate as shrinkage resistance for UV-curing 3D printing: UV-curing kinetics, mechanical properties and volume shrinkage

Spiroorthocarbonates (SOCs) exhibit good shrinkage resistance with ring-opening polymerization initiated by a cationic photoinitiator, with potential application in reducing the volume shrinkage by C=C double bond polymerization on three-dimensional (3D) printing. However, SOCs as an additive dealing with volume shrinkage in 3D printing are rarely reported. Moreover, little progress has been made in the kinetics study on its ring-opening polymerization. In this study, we presented an effective strategy to reduce 3D printing volume shrinkage based on SOCs chemistry and systematically studied the ring-opening photopolymerization kinetics. 3,9-diethyl-3,9-bis(allyloxymethyl)-1,5,7,11-tetraoxastetraoxaspiro undecane (DB-TOSU), one kind of SOCs, was adopted as an expanding monomer. Initiated by cationic photoinitiator with sensitizer under 405 nm LED light, the maximum conversion of DB-TOSU is up to 84%. As a volume-control agent for 3D printing, volume shrinkage reduction is 71.2% when adding DB-TOSU into 3D printing resin based on SOCs chemistry. Moreover, the toughness of resin was enhanced. In the 3D printing application test, DB-TOSU displayed a good application prospect owing to its good compatibility with the printing resin and printing accuracy after volume expansion.