AbstractThe copolymerization of 9,9‐dimethyl‐4‐methylene‐3,5,8,10‐tetraoxabicylco[5.3.0]decane(4)with 3,9‐bismethylene‐2,4,8,10‐tetraoxaspiro[5.5]undecane(5)was investigated. While4polymerizes after radical attack to form highly viscous linear polyesters with a number‐average molecular weight of 5000, the addition of5in variable amounts leads to insoluble samples. It is shown that the material properties can be controlled by using various contents of5in the storable and persistable monomer4. According to the application purpose, it is possible to produce gel‐like or rubber‐like as well as