Encouraged by these results, but cognizant of the fact that using a dichlorosilanes for repolymyerization does not constitute a fully "closed-loop" process due to need for new silane coupling "monomers" in each cycle, we sought an alternative route to chemical recycling of these systems that leverages the dynamic covalent chemistry of Si-O bonds. While precedent for acid-catalyzed Si-O bond exchange was established in polydimethylsiloxanes as early as the 1950s and has since been leveraged for reprocessing of various thermosetting systems, to our knowledge, this reactivity has never been used to execute a chemical recycling strategy. To demonstrate this idea, i PrSi8-co-PE-50 was treated with a large excess of n-propanol (>100 equiv. per BSE) in toluene in the presence of a catalytic amount of octanoic acid at 80 ºC. These conditions facilitated an Si-O bond exchange reaction between n-propanol and the BSEs in the i PrSi8co-PE-50 backbone, yielding hydroxy-terminal deconstruction products and diisopropyldipropoxysilane through Si-O bond exchange (Figure , bottom, Figures ). SEC reveals that this process deconstructs the polymer backbone to a similar extent as acid or fluoride-mediated bond cleavage (Figure , light red trace, Table ). An advantage of the bond exchange approach, however, is that reconstruction of the backbone can be achieved by simply exposing the diol products to diisopropyldipropoxysilane and increasing the reaction temperature above the boiling point of n-propanol (100 ºC) to drive off n-propanol and favor repolymerization. Following complete removal of n-propanol, proton H a is no longer present in the 1 H NMR spectrum, suggesting full conversion back to recycled polymer (Figure ). SEC further shows nearly complete recovery of high molar-mass material upon repolymerization (39.6 kDa, Figure , dark red trace, Table ). These results show that it is possible to chemically recycle these polymers via a simple thermal equilibrium with an alcohol in the presence of an acid catalyst (octanoic acid), thereby avoiding the need for fresh silane reagent and representing a fully "closed-loop" process. Large-scale recycling efforts are typically preceded by sorting of mixed plastic waste streams with either mechanical or sink-flow density separation techniques. Commodity polyolefins, namely polypropylene (PP), HDPE, and poly(ethylene terephthalate) (PET) comprise more than half of the plastic waste stream. Thus, it may be advantageous to leverage the selective Si-O bond cleavage of our materials to facilitate their separation from these polyolefins. To demonstrate this concept, pieces of commercial isotactic PP (food storage container), HDPE (squeeze bottle cap), PET (reusable collapsible water bottle), and i PrSi8-co-PE-50 were subjected to the acid-mediated deconstruction conditions used above for our PE mimics (Figure ). While i PrSi8-co-PE-50 dissolved within 2 h, the PP, HDPE, and PET segments were recovered with no significant mass loss (Figure ). The HDPE surface appeared slightly discolored after extended contact with these conditions, but given the minimal change in mass, negligible leeching or dissolution were observed. Successful separation was further confirmed by 1 H NMR of the post-deconstruction solution, which matched spectra of the diols obtained for i PrSi8-co-PE-50 deconstruction (Figures ). Characteristic features corresponding to dissolution of the commodity plastics (e.g., PET resonances at approximately 4.8 and 8.1 ppm) were not observed.