Investigation on the thermal degradation of acrylic polymers with fluorinated side-chains

The thermal degradation of poly-2,2’,3,3’,4,4’,5,5’,6,6’,7,7’,7’’-tridecafluoroheptylacrylate and poly-2,2’,3,3’,4,4’,5,5’,6,6’,7,7’-dodecafluoroheptylmethacrylate has been studied in isothermal conditions at 450-750°C using pyrolysis-gas chromatography techniques. The type and composition of the pyrolysis products give useful information about mechanism of thermal degradation. It was shown that the main thermal degradation process for both polymers is the random main-chain scission. The major degradation products for fluorinated polyacrylate are monomer, dimer, saturated diester, trimer, and corresponding methacrylate. The fluorinated polymethacrylate gives monomer as main product of thermodestruction. As result of side-chain reaction, the thermodegradation of the fluorinated polyacrylate produces also remarkable alcohol amounts. On the other hand, the respective alcohol is only a minor component among the pyrolysis products of the fluorinated polymethacrylate. For both polymers, the main nontrivial degradation product coming from the alkyl ester decomposition is the corresponding fluorinated cyclohexane. The formation of the fluorinated cyclohexanes may be accounted for a nucleophilic bimolecular substitution pathway.