Frontal Polymerization of Dihydrofuran Comonomer Facilitates Thermoset Deconstruction
Oleg Davydovich, Justine E. Paul, John D. Feist, Jia En Aw, Francisco Javier Balta Bonner, Jacob J. Lessard, Sameh Tawfick, Yan Xia, Nancy R. Sottos, Jeffrey S. Moore
Abstract
Frontal ring-opening metathesis polymerization (FROMP) is a rapid, low-energy manufacturing reaction that is useful for curing thermosetting materials. FROMP of dicyclopentadiene (DCPD) results in poly(dicyclopentadiene) (p(DCPD)), a tough thermoset with excellent mechanical performance and chemical stability. Like most thermosets, p(DCPD) cannot be reprocessed and is therefore difficult to recycle. Previous work demonstrated that the incorporation of a small quantity of cleavable units in the strand segments of p(DCPD) networks enables their deconstruction. Here, we report that a commercially available multifunctional comonomer, 2,3-dihydrofuran (DHF), both acts as a potent Grubbs catalyst inhibitor during FROMP and introduces acid cleavable units. The resulting materials retain high performance characteristics, including glass-transition temperatures ranging from 115 to 165 °C and ultimate strength ranging from 35 to 40 MPa. The addition of DHF above critical loading levels enables deconstructable thermosets. We further demonstrate freeform three-dimensional (3D) printing of deconstructable thermosets via frontal polymerization.