This article describes poly(benzyl ethers) that depolymerize from head-to-tail when an end-cap on the terminus of the polymer is cleaved from the polymer through a specific activity-based detection event. The polymers are prepared in high yields with short polymerization times and are accessible in lengths extending to thousands of repeating units. End-caps are introduced with a variety of functional groups, which provides access to polymers with selective response properties. The end-capped polymers are stable to acid, base, and heat, but depolymerize completely within minutes of removal of the end-cap and treatment of the un-end-capped polymer with base.