Reversible crosslinking and fast stress relaxation in dynamic polymer networks via transalkylation using 1,4-diazabicyclo[2.2.2] octane†
Dynamically crosslinked polymers offer the possibility to design materials that have the robustness of thermosetting materials and the reshapability of thermoplastic materials. A reversible crosslinker based on transalkylation chemistry using 1,4-diazabicyclo[2.2.2]octane (DABCO) was developed. The kinetics of the exchange reaction of benzyl bromide with DABCO was studied in detail by varying molar ratios and temperature. The system showed efficient exchange without addition of a catalyst. Reversibility in a polymer was studied by the crosslinking of a linear, benzylic bromide functionalized polyacrylate with DABCO. The resulting network was insoluble in common solvents, but it readily dissolved in the presence of DABCO. Rheological measurements showed that the crosslinks are dynamic, with a strong temperature dependent relaxation that at 140 °C is faster than for other transalkylation based dynamic networks reported in the literature.