The ever-worsening worldwide plastic pollution, which is accompanied by enormous materials value loss to the global economy, is largely caused by current unsustainable practices in the generation and disposal of synthetic polymeric materials. To address this global challenge several approaches have been intensively pursued. Among such approaches the development of chemically recyclable polymers that can be completely and repeatedly depolymerized back to their building-block monomers for virgin-quality polymer reproduction promises a circular materials economy approach to address these dire environmental and economic issues. However, realization of such reversible polymers must solve three challenges: energy cost, depolymerization selectivity, and depolymerizability/performance tradeoffs. Centering on addressing the above identified challenges, this presentation will first introduce a synthetic methodology to render an important class of biorenewable and biodegradable polymers with a full chemical lifecycle. Next, the presentation will describe the design and discovery of infinitely recyclable plastics that are not only thermally and mechanically robust to be practically useful but also thermally and/or chemically depolymerizable with quantitative selectivity for clean monomer recovery and polymer reproduction under cost-effective polymer assembly and disassembly conditions.