Cyclopentadiene-functionalized polyketone as self-cross-linking thermo-reversible thermoset with increased softening temperature

Self-cross-linkable thermo-reversible thermosets were obtained by a two-steps post-functionalization of aliphatic alternating polyketones yielding two different cyclopentadiene functionalization degree of 9 and 22% (with the respect of initial 1,4-dicarbonyl units). Thermo-reversibility was verified by gelation experiments and differential scanning calorimetry (DSC) scans displayed a broad transition varying from 75-100 degrees C till 160 degrees C that can be related to retro-Diels Alder de-bonding of the dicyclopentadienyl moieties. The dynamic mechanical thermal (DMTA) analysis showed the complete thermo-mechanical recovery of the material up to six thermal cycles with a softening temperature around 210 degrees C, thereby ensuring a suitable application window for high-temperature resistant thermosets. Independently of the exact mechanism at the molecular level and in addition to previous studies which used the same Diels-Alder diene-dienophile system, it must be noticed that all prepared materials retained their mechanical behavior during at least six consecutive thermal cycles, thus indicating the re-workability of the system. (C) 2015 Wiley Periodicals, Inc.