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

Abstract

Reversible networks based on an alkene-functionalized 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 1,2,4-trivinylcyclohexane 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 °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 °C. Irradiation of these anthracene monomers resulted in the formation of networks having similar physical properties as the original materials.