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

Abstract

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 75-1008C till 1608C 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 2108C, 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. V C 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42924.

The Use of Click-Type Reactions in the Preparation of Thermosets

“…As a diene, furan derivatives have been widely used, e.g., in the work by Gandini et al [170][171][172]. Other dienes such as cyclopentadiene [173] or anthracene [174,175] -functionalized compounds have also been reported. As dienophiles, maleimides are the most commonly employed [176,177], although Du Prez et al proposed the use of 1,2,4-triazoline-3,5-dione (TAD).…”

Recent Advances in Synthesis of Non-Alternating Polyketone Generated by Copolymerization of Carbon Monoxide and Ethylene

“…As a kind of engineering plastic, PKs show unusual properties such as conspicuous chemical resistance, impermeability to hydrocarbons, high impact strength, and good thermostability [17,18]. Various modifications [19][20][21][22][23][24][25][26][27] and post-functionalizations of PKs widely expand their potential applications in biomedicine, electronic devices, fluorescent materials, and textile fibers [17,[28][29][30][31]. Most importantly, PKs are a kind of degradable polymeric material, and their degradation can be induced by UV light irradiation through the well-known Norrish I and II processes [32][33][34][35][36][37].…”

Norbornadienes: Robust and Scalable Building Blocks for Cascade “Click” Coupling of High Molecular Weight Polymers

“…The high reactivity of TAD compounds offers an elegant method for functionalizing polymers when less reactive dienes are required. In contrast, the reactivity of the diene can be increased through the use of cyclopentadiene (Cp) derivatives. , Recognizing the potential of Cp as a polymer click platform, Barner-Kowollik and co-workers developed synthetic routes to access Cp-functionalized polymers for conjugation with maleimides, electron-deficient dithioesters, − and carbon nanoparticles. , For stable backbones such as polystyrene or poly­(ethylene glycol), nucleophilic substitution using ionic cyclopentadienyl salts (NaCp, LiCp, or Me 2 AlCp) allows for the efficient synthesis of Cp-functionalized chain-end derivatives. In the case of reactive backbones, such as polyesters, an alternative substitution strategy using nickelocene (NiCp 2 ) has been developed. ,, Despite the success of these strategies, the ability to incorporate Cp has been limited to chain ends via postpolymerization strategies due to the general instability of Cp and its high reactivity toward electron-deficient vinyl monomers …”

“…23,24 Recognizing the potential of Cp as a polymer click platform, Barner-Kowollik and co-workers developed synthetic routes to access Cp-functionalized polymers for conjugation with maleimides, 25 electron-deficient dithioesters, 26−28 and carbon nanoparticles. 29,30 For stable backbones such as polystyrene or poly(ethylene glycol), nucleophilic substitution using ionic cyclopentadienyl salts (NaCp, 26 LiCp, 31 or Me 2 AlCp 32 ) allows for the efficient synthesis of Cp-functionalized chain-end derivatives. In the case of reactive backbones, such as polyesters, an alternative substitution strategy using nickelocene (NiCp 2 ) has been developed.…”