A perfluoropolyether-based elastomers library with on-demand thermorheological features
Résumé
Perfluoropolyether (PFPE)-based materials were obtained through thermal 1,3-dipolar Huisgen
reactions. The formulations consisted in a combination of PFPE-functionalized oligomers (PFPEdiyne
A2 and PFPE-diazide B2) and a pentaerythritol triazide cross-linker C3. Increasing the
amount of C3 induced an increase of the cross-link density. This approach gave rise to materials
ranging from rubber-like to gels. The networks formation was found to be governed by a constant
activation energy and it was assumed that the whole process is controlled by the fast reaction
between A2 and C3. Two glass transition temperatures were evidenced, one ascribed to hydrogen
bonds that gradually shifted to a lower temperature with decreasing C3, while the other one was
attributed to PFPE segments that constantly appeared at -−105 °C. Thermogravimetric analyses
under air recorded at a low heating rate of 1 °C min−1 provided a valid estimate of the true
temperature of degradation of the materials (ca. 200 °C).