(3-Ethyloxetan-3-yl)methyl methacrylate is a functional monomer that belongs to the oxetane family. It reacts with other reactive monomers in a polymerization reaction to form polymers. The functional groups on this compound are ester and ether. This compound can be used as an optical modifier in photopolymerizable compositions, due to its high refractive index and low absorption coefficient. It also has been used as an initiator for cationic polymerization reactions, such as acrylation reactions, which allow for copolymerizations of different compounds. The ring opening of the oxetane ring is the rate limiting step in this polymerization process, which occurs at a rate dependent on the activation energy of the reactants. The molecular weight of these polymers depends on how many chain initiating units are present.