While vat photopolymerization (VP) is one of the premier additive manufacturing techniques, it imposes limitations for a photocurable resin to be viable. One of the severest limitations is the low viscosity requirement which prevents high molecular weight (MW) polymers from being printed, until recently. Our group developed an unprecedented method for circumventing the compromises imposed by VP through formulating a photosensitive latex resin that allowed for high MW polymers to be used due to the decoupling of viscosity from MW. This is realized by compartmentalizing the polymer chains into discrete particles, which are allowed to coalesce after 3D printing the hydrogel green body. However, the monomers used to form the hydrogel green body resulted in decreased ultimate material properties due to the high crosslink density employed. Herein we report a novel scaffold system that allows for facile printing and simultaneously enhances the final material properties. This is achieved through use of an acid-labile crosslinker in conjunction with N-vinylpyrrolidone, which forms a glassy polymer after photocuring. Subsequent reactive extraction removes the crosslinks and liberates the glassy polymer giving rise to mechanical reinforcement of the geometrically complex VP elastomer. Ultimate strain and stress values of over 650% and 8.5 MPa respectively are achieved, setting a new benchmark for VP elastomers.

Additive manufacturing of elastomeric nanocomposites: A degradable scaffold approach

ACS Fall 2021

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