metharylate monomer having an octanal‐derived bicyclobisoxazolidine (BBOX) moiety was synthesized and was radically copolymerized with a methacrylate having a hydrophilic poly(ethylene glycol) chain to obtain an amphiphiliccopolymerhaving the BBOX moieties as hydrophobic sidechains. The BBOX moieties were stable for 7 days at pH 7.0, whereas they were gradually hydrolyze at pH 5.0 to release octanal continuously