Recently, it has been shown that the reaction mechanism in self-healing diphenyl dichalcogenide-based polymers involves the formation of sulfenyl and selenyl radicals. These radicals are able to attack a neighbouring dichalcogenide bond via a three-membered transition state, leading to the interchange of chalcogen atoms. Hence, the chain mobility is crucial for the exchange reaction to take place. In this work, molecular dynamics simulations have been performed in a set of disulfide- and diselenide-based materials to analyze the effect of the molecular structure in the chain mobility. First of all, a validation of the computational protocol has been carried out, and different simulation parameters like initial guess, length of the molecular chains, size of the simulation box and simulation time, have been evaluated. This protocol has been used to study the chain mobility and also the self-healing capacity, which depends on the probability to generate radicals ( $\rho$ ), the barrier of the exchange reaction ( $\Delta G$ ) and the mobility of the chains ( $\omega$ ). The first two parameters have been obtained in previous quantum chemical calculations on the systems under study in this work. After analyzing the self-healing capacity, it is concluded that aromatic diselenides (PD-SeSe) are the best candidates among those studied to show self-healing, due to lower reaction barriers and larger $\omega$ values.

Radical ring-opening polymerization (rROP) of cyclic ketene acetals (CKAs), particularly 2-methylene-1,3-dioxepane (MDO), offers a robust pathway to introduce degradable ester linkages into nondegradable vinyl backbones. However, the rational design of these materials is currently hindered by highly comonomer-dependent open-to-closed (ester vs acetal) incorporation ratios. In this study, a rigorous density functional theory (DFT) framework integrating systematic conformational sampling and implicit solvation is employed to establish a unified structure–reactivity map for MDO copolymerization across a diverse set of vinyl monomers. The computational results reveal that while MDO homopolymerization is thermodynamically driven toward quantitative ring opening due to the irreversibility of the open-chain radical, copolymerization is governed by a fine-tuned competition between the kinetic accessibility of vinyl addition and the stability of the resulting cyclic adduct. The closed-propagation barrier is primarily dictated by a SOMO–LUMO interaction, where the electronic nature and α-substitution of the comonomer modulate orbital overlap and energy. Three distinct reactivity regimes are identified: (1) high open incorporation (e.g., MDO, crotonates), where high vinyl barriers and adduct reversibility favor β-scission; (2) intermediate competition (e.g., vinyl acetate); and (3) ring-retention dominance (e.g., acrylates), where rapid vinyl addition and deep thermodynamic stabilization suppress the degradable pathway. This work provides a qualitative molecular basis for the rational selection of comonomers to maximize CKA incorporation in the open form for next-generation sustainable vinyl polymers.