A Novel Crosslinking–Decrosslinking System of Polymers Having Spiro Orthoester Moieties in the Side Chains

Acid-catalyzed reversible crosslinking–decrosslinking of polymers having spiro orthoester groups in the side chains was carried out. The copolymers obtained by the radical copolymerizations of 2-methylene-1,4,6-trioxaspiro[4.6]undecane with acrylonitrile, methyl, cyclohexyl, and 2-ethylhexyl acrylates were treated with trifluoroacetic acid (5 mol%) at −10 °C for 1 h in CH2Cl2 (4.2 M) to afford the crosslinked polymers in 69—99% yields. The crosslinked polymers were then treated with trifluoroacetic acid at a low concentration (0.1 M) in CH2Cl2 at room temperature for 1 h to give the original polymers in 55—99% yields. These results strongly support the conclusion that the acid-catalyzed reversible crosslinking–decrosslinking of the polymers possessing the spiro orthoester groups in the side chains could be constructed.