Mono- and di-functional norbornene dicarboximide monomers containing acetal ester groups were synthesised. The ROMP of the di-functional monomer using Grubbs ruthenium first generation initiator at ambient temperature produced crosslinked material. Materials with various crosslink densities were prepared by the ROMP, under the same condition, of mixtures of the mono- and di-functional monomers. The FT-IR spectra clearly showed the presence of an acetal C-O band at 1135 cm(-1). The TGA study of the crosslinked materials showed that they are stable to 150 degrees C and that they exhibit rapid breakdown at about 200 degrees C, as the result of the thermal decomposition of the acetal ester linkage. FT-IR analysis of the retrieved materials following TGA-MS showed that the intensity of acetal C-O band at 1135 cm(-1) was greatly reduced. (C) 2010 Elsevier Ltd. All rights reserved.