Under the optimal condition, the scope of the cis-selective ADMET was then investigated. Nine different monomers with diverse functional and skeletal features were examined, leading to polyalkenamers with a cis percentage ranging from 96% to 99%, except for P8 (Scheme 3). Among these, polyester P1, polysulfite P2, polycarbonate P3 and polyether P4 could all be accessed with molar masses larger than 10 kg mol -1 and cis percentage over 97%. Chlorinated P5 and polysiloxane P6, which possess additional handles for post-polymerization functionalization and/or remolding, could also be accessed with high cis-selectivity (97-98% cis). Moreover, di(but-3-en-1-yl) fumarate, a readily available terminal diene from fumaric acid, could also be employed. While the newly formed double bonds are 99% cis, the electron-deficient trans-double bonds are well-preserved in the main-chain of P7, providing electro-and radicalphilic reactivity for further elaboration. to poor solubility, polyether P8 and unfunctionalized P9 were prepared in 1,2-dichlorobenzene instead of 1,4-dioxane. Additionally, increasing the catalyst loading from 0.3 mol% to 0.6 mol% could increase the molar mass of P7 from 8.2 kg mol -1 to 9.7 kg mol -1 . The thermal properties of the synthesized cis-polyalkenamers were measured using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and found to be consistent with the previous assessment. Among them, the melting temperature (Tm) of the all-cis P1 could be measured and found lower than a transenriched P1. Besides thermal properties, we further aim to evaluate the chemoselectivity of the cis-selective ADMET against main-chain trans olefins. As Ru-4 demonstrates high stereoselectivity in forming cis-olefins during ADMET, assuming that 1,2-disubstituted trans-double bonds in monomers could be completely left alone, a convenient approach towards well-defined polyalkenamers with precisely-positioned cis-trans configuration could be envisioned (Scheme 4a). As a model substrate, triene 10 with a centered transdouble bond was prepared in a single step from trans-β-hydromuconic acid, which is unsuitable for ADMET using conventional catalysts like G2. If the chemoselectivity of Ru-4 is flawed and the centered trans double bond cannot be completely left untouched, the formation of but-3-enoate and/or β,γ-unsaturated δ-lactone (11), even in a small amount, would be expected as an indicator. To our delight, no lactone 11 or other significant side processes was observed in the ADMET of 10 using Ru-4, indicating perfect chemoselectivity. The generated semi-crystalline polyester P10, with a medium molar mass of 5.8 kg mol -1 , possesses a precise cisa-trans configuration, a non-trivial feature that makes it valuable for structure-property investigations and as models for imprecise systems. Besides, we found that P10 underwent facile depolymerization in the presence of G2 and furnished 11 in >98% yield, thus representing an intriguing switch between an ADMET polymerization and an RCM depolymerization (Scheme 4b). The well-tolerance of main-chain trans-double bonds appears to be universally useful for constructing stereo-controlled polymers. In another case, polyether P12, with an alternatively configured main chain, could also be produced through the same Ru-4-catalyzed ADMET from triene 12. 23 Scheme 5. Synthesis and depolymerization of a cross-linked cis-ADMET-derived polymer.