Rapid bonding/debonding on demand: Reversibly cross-linked functional polymers via diels-alder chemistry

The synthesis of a novel poly(methyl methacrylate) (PMMA) chain bearing Cp functionality at both chain ends and a trifunctional pyridinyldithioformate linker molecule, which are able to rapidly and reversibly cross-link on demand within a highly accessible temperature range was reported. The ATRP initiator 1,2-bis(bromoisobutyryloxy)ethane was synthesized. Methyl methacrylate was passed through a short column of basic alumina and stored at -19°C prior to use. Copper(I) bromide (Fluka) was purified by sequential washing with sulfurous acid, acetic acid, and ethanol, followed by drying under reduced pressure. ¹H NMR spectroscopy was performed using a Bruker AM 250 spectrometer at 250 MHz for hydrogen nuclei and 100 MHz for carbon nuclei. Size exclusion chromatography measurements were performed on a Polymer Laboratories. It is observed that a sharp increase in the absorbance of the system occurs at around 80 °C, corresponding to the rapid onset of debonding.