Abstract: A method to synthesize a low thermal expansion thermoset comprises mixing a thermosetting resin and a benzocyclobutene curative having a reactive secondary functionalization; heating the mixture to a first temperature to from a pre-polymer comprising benzocyclobutene end groups and a thermoset linking group; and heating the pre-polymer to a second temperature sufficient for ring-opening of benzocyclobutene to occur, thereby forming a thermoset polymer network crosslinked with dibenzocyclooctene moieties.

Abstract: The invention is directed to the selective dual wavelength olefin metathesis polymerization for additive manufacturing. Dual-wavelength stereolithographic printing uses ring-opening metathesis polymerization of the metathesis-active polymers. As an example, a resin formulation based on dicyclopentadiene was produced using a photolatent olefin metathesis catalyst, various photosensitizers and photobase generators to achieve efficient initiation by light at one wavelength (e.g., blue) and fast catalyst decomposition and polymerization deactivation by light at a second wavelength (e.g., ultraviolet). This process enables 2-dimensional stereolithographic printing, either using photomasks or with patterned, collimated light. Importantly, the same process was readily adapted for 3-dimensional continuous additive manufacturing, with printing rates of up to 36 mm h?1 for patterned light and up to 180 mm h?1 using un-patterned, high intensity light.