A series of copolymers containing different ratios of methyl methacrylate and 2-(dimethylamino)ethyl methacrylate has been synthesised by conventional free radical polymerisation. These copolymers have been converted into a series of novel salts by reaction with the acid monomers, methacrylic acid, methacryloyloxyethyl phosphate and vinyl phosphonic acid. The copolymers and the corresponding salts have been characterised fully by a range of spectroscopic and thermal analysis techniques. The nature of the salt has a characteristic effect on the thermal degradation of the polymer. The presence of the phosphorus monomers leads to formation of residual char, even at temperatures as high as 1000 degreesC. (C) 2003 Elsevier Science Ltd. All rights reserved.