Anthracene-Based Thiol-Ene Networks with Thermo-Degradable and Photo-Reversible Properties

Reversible networks based on an alkenefunctionalized dimer of 9-anthracenemethanol were synthesized by photoinitiated radical thiol ene polyaddition, using either a poly(dimethylsiloxane-co-propylmercaptomethylsiloxane) or a novel aliphatic trithiol synthesized from 1,2,4trivinylcyclohexane in a simple two-step procedure. The obtained networks were analyzed using differential scanning calorimetry, dynamic mechanical analysis, polarization microscopy, X-ray diffraction, and (photo)rheology. The two types of networks showed weak endothermic transitions between 50 and 60 degrees C, which proved to originate either from melting of a crystalline anthracene-dimer phase (trithiol network) or from a liquid crystalline phase (PDMS network) based on X-ray diffraction and polarization microscopy. Using rheology, both types of networks were shown to cleanly decompose into multifunctional anthracene monomers at temperatures above 180 degrees C. Irradiation of these anthracene monomers resulted in the formation of networks having similar physical properties as the original materials.