Continuous Additive Manufacturing using Olefin Metathesis

Abstract

The development of chemistry is reported to implement selective dual-wavelength olefin metathesis polymerization for continuous additive manufacturing (AM). A resin formulation based on dicyclopentadiene is produced using a latent olefin metathesis catalyst, various photosensitizers (PSs) and photobase generators (PBGs) to achieve efficient initiation at one wavelength (e.g., blue light) and fast catalyst decomposition and polymerization deactivation at a second (e.g., UV-light). This process enables 2D stereolithographic (SLA) printing, either using photomasks or patterned, collimated light. Importantly, the same process is readily adapted for 3D continuous AM, with printing rates of 36 mm h -1 for patterned light and up to 180 mm h -1 using un-patterned, high intensity light.

Photoinitiated Olefin Metathesis and Stereolithographic Printing of Polydicyclopentadiene

“…Expanding irradiation wavelengths to the visible range is of great interest for SLA AM in order to improve the variety of useful chemistries, composites, and accessible multimaterials . Our group recently demonstrated the use of two alternative photosensitizers to ITX, camphorquinone (CQ) and benzil, for the acceleration of photoROMP and SLA AM of Ru-1 catalyzed DCPD resins . Importantly, these photosensitizers were shown to initiate photoROMP more rapidly than ITX at higher wavelengthsa capability leveraged for wavelength-dependent activation of two distinct photochemistries (e.g., SWOMP).…”

“…In particular, ring-opening metathesis polymerization (ROMP) is an excellent method for the synthesis of polymers with well-defined molecular weights and monomer sequences, − high thermomechanical and chemical property ceilings, − and controlled stereochemistries. ,− Polydicyclopentadiene (pDCPD), a thermosetting polymer produced by ROMP of dicyclopentadiene (DCPD), has been of notable interest to academia as the relatively high ring-strains of the norbornene and cyclopentene moieties in DCPD provide sufficient reactivity for its use as a model compound in catalyst development (Figure a). , Additionally, pDCPD has found broad industrial use due to its high impact strength, desirable chemical and thermal stability, and corrosion resistance properties. ,, Applications of pDCPD include heavy-vehicle paneling, sporting equipment, and electrolytic cell coverings. − Thus far, the applications of pDCPD are limited to large parts with relatively simple geometries produced by reaction injection molding due to the use of highly active transition metal catalysts (e.g., ruthenium) that rapidly polymerize DCPD upon mixing of monomer and catalyst. Recent developments in latent catalysis and additive manufacturing (AM) of olefin metathesis resins offer exciting alternative methods for the manufacturing of pDCPD to achieve complex, highly resolved architectures not possible with traditional processing techniques. − …”

“…The greatly accelerated rate of photoROMP achieved using Ru-1 and a photosensitizer, 2-isopropylthioxanthone (ITX), enabled the AM of complex, three-dimensional pDCPD architectures via DIW. Later work utilized alternative photosensitizers to red-shift the activation wavelength for use in selective dual-wavelength olefin metathesis polymerization (SWOMP), a continuous-stereolithographic AM technique . The serendipitous identification of Ru-1 (HeatMet) as a photolatent catalyst with a rapid initiation time led us to wonder what other commercial catalysts are capable of rapid photoROMP suitable for 3D printing applications.…”

3D printing of bone and cartilage with polymer materials

“…So as to add optical curing light-sensitive resin layer by layer, until it forms a complete formation the process of three -dimensional device ( Dadras-Toussi et al, 2022a ). Because the light -sensitive resin has unique liquid liquidity and instantaneous light solidification characteristics and the amount of light sensitivity resin can accurately control the amount and space of the light sensitivity resin ( Foster et al, 2022 ). The optical solidification 3D printing can create a prototype with any complex geometric shape that is difficult to prepare with traditional processing methods.…”

Additive Manufacturing of Degradable Materials via Ring-Opening Metathesis Polymerization (ROMP)

“…Ring-opening metathesis polymerization (ROMP) has emerged as a versatile chemistry for additive manufacturing (AM). Recently, photoactivated Ru catalysts with unique isomerization-driven activation have been designed, , photoacid and photoredox catalyst systems reported, , a photoinititation mechanism applied to frontal polymerization (FROMP), and stereolithographic printing methods implemented for olefin metathesis chemistry. − Indeed, we now understand that most Ru-based olefin metathesis catalysts can be photoactivated, either directly or using photosensitizers, providing ready access to a broad range of light-based manufacturing techniques classified by the term photoROMP.…”