This difference is consistent with previous reports on ring-closing metathesis where reaction rates are affected by exocyclic allylic substituent bulk, and supports the inclusion of penultimate effects in characterizing this reaction. Moreover, these corrected values correspond to more strongly alternating copolymerization behavior based on traditional heuristics (i.e., the value of 𝑟 /@AMNE × 𝑟 >O$5>7 is lower), which is illustrated by stochastic simulations of comonomer sequences (Figure ). Encouraged by this result, we characterized polymerizations of three other equilibrium comonomers of interest (iPrSi7, iPrAc7, and iPrAc8 in Figure ) with endo-NB. Our groups have previously employed these comonomers (alongside iPrSi-8) as additives to enable degradable poly(endo-dicyclopentadiene) thermoset materials, an application where prediction of network degradability is highly sensitive to comonomer reactivity, and for which endo-NB serves here as a surrogate to assess the reactivity in these systems without the possibility of crosslinking. Similar real-time experiments were performed and comonomer consumption data for iPrSi7, iPrAc7, and iPrSi8 were fit analogously. We note than iPrAc8 has an equilibrium concentration that could be measured (32 ± 6 mM), while no polymerization was observed when Grubbs third generation bis-pyridyl complex was added to neat iPrAc7 or iPrSi7, suggesting that the equilibrium concentration for these two monomers is above their bulk concentration. In all cases, the model fit the data well, and the best fit parameters are listed in Table . Fitting these data using the Meyer-Lowry equation gave worse fits (as determined by the value of SSR, typically more than one order of magnitude larger, Table ) and statistically significantly different values of reactivity ratios were obtained, highlighting the importance of using accurate models to fit data to discern specific trends. Interestingly, the best fit value of equilibrium concentration for iPrSi7 is below its bulk concentration (1.5M versus ~5M), suggesting that bulk homopolymerization should be feasible from a thermodynamic perspective. This is in-line with our observations of no homopolymerization under modest solution conditions (1M) but contrasts with our observation of no homopolymerization from the bulk. We posit then that absence of homopolymerization under bulk conditions for iPrSi7 may be due to other effects, such as the possibility of a deleterious monomer isomerization-catalyst deactivation process. Within this library of monomers, distinct copolymerization reactivity is observed based on the measured reactivity ratios: both iPrSi8 and iPrAc7 display strong alternating tendency as both reactivity ratios are < 1 (however, total iPrAc7 incorporation is minimal), while iPrSi7 copolymerizes with gradient behavior, and iPrAc8 copolymerizes in a blocky fashion (both rendo-NB, riPrAc8 >1). We posit that such distinct reactivity behavior may explain differences in the efficacy for degradability in pDCPD copolymer systems with each of these cleavable comonomers. Further correlation of cleavable comonomer structure and thermoset/plastic deconstruction behavior guided by these results are underway in our laboratories.