The synthesis and characterization of supramolecular elastomers based on linear carboxyl-terminated polydimethylsiloxane oligomers

Supramolecular elastomers obtained through a two-step reaction of linear carboxyl-terminated polydimethylsiloxane oligomers (PDMS-COOH2) with diethylenetriamine (DETA) and urea show reasonable hysteresis and acceptable self-healing properties. The results of temperature-dependent infrared analysis suggest the existence of hydrogen bonding interactions with good thermal reversibility in the matrix. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses demonstrate that the supramolecular network structure is totally amorphous at room temperature. The rheological, mechanical and self-healing properties are closely related to the PDMS chain length, whereas the stability seems to be independent of the PDMS chain length. The viscoelastic properties of these materials are believed to be the result of entangled chains in the amorphous matrix. Only the hydrogen bonds formed by 1,1-dialkylurea groups and imidazolidone derivatives serve as effective crosslinks for contributing to the stability of the supramolecular network.