Here, we introduce linear HDPE containing Si-O linkages, specifically, bifunctional silyl ethers (BSEs), i.e., SiR2(OR'2). BSEs combine excellent thermal and oxidative stability with the capability to undergo selective cleavage on demand. Additionally, the Si substituents of BSEs can be tuned, leading to variable properties such as Si-O bond hydrolytic cleavage rate. First, we develop conditions for the catalytic ROMP of BSE-containing cyclic olefins in the presence of cyclooctene, which following hydrogenation enables access to BSE-based HDPE of variable molecular weight, including the highest reported molecular weight for any reported ROMP-derived PE mimic. We show that these Si-O containing materials have crystal structures and thermal stabilities on par with commercial HDPE, and that their crystallinities can be tuned by varying the BSE loading or the Si substituents (e.g., i Pr versus Et). We demonstrate two alternative routes for chemical recycling of these materials: first, using selective Si-O bond cleavage to produce oligomeric diols suitable for repolymerization; and second, through octanoic acid-catalyzed Si-O bond exchange using propanol to give a fully circular process. We show that these step-growth repolymerization processes generate recycled BSE-based HDPE with molar masses nearly identical to the parent sample, despite their fundamental differences in polymerization mechanism. Finally, we show that BSE-based HDPE and its chemically recycled products display tensile properties on par with commercial HDPE, suggesting that they could be used as PE replacements in high-value applications.