Stereolithographic 3D printing of pure poly(ether–ester) networks from spirocyclic monomers via cationic ring-opening photopolymerization at high temperatures

Abstract

We demonstrate for the first time stereolithographic (SL) printing of pure poly(ether–esters) based on cationic ring-opening photopolymerization without the need to accelerate curing via radical mechanisms. To minimize shrinkage stress in bulk-photopolymer parts, spiro-orthoesters have been utilized as expanding monomers. In combination with a bifunctional spiro-orthoester or epoxide, previously inaccessible pure aliphatic poly(ether–ester) parts have been printed via Hot Lithography, an SL process at elevated temperatures. Precision part size, high resolution and excellent surface-finish could be achieved. During monomer evaluation, the changes in reactivity and polymerization mode of photopolymerization at elevated temperatures were investigated with photo-DSC analysis. Convincing (thermo-)mechanical properties of the cured materials were determined with DMTA and tensile testing. This technological advance gives access to SL manufacturing of a highly regarded material class due to the biocompatibility and biodegradability of aliphatic poly(ether–esters), which frequently find application in medical applications where flexible and highly precise part design is key.