Study of the thermal elimination process of sulphinyl-based PPV precursors by solid state NMR

A sensitive protocol to judge the completeness of the elimination reaction for soluble and insoluble conjugated polymers prepared via precursor routes is presented based on UV/vis and 1H wideline NMR relaxometry in the solid state. Especially the proton spin-lattice decay time in the rotating frame, T1ρH, has proven to be suitable for an accurate determination of the completeness of the elimination reaction. Especially for long side-chain substituted PPV derivatives, UV/vis seems to be limited due to thermochromic effects. Furthermore, it is shown by solid state 2H wideline NMR spectroscopy that incomplete elimination results in an enhanced polymer backbone chain mobility. Both the completeness of elimination and insight into the molecular dynamics can be of significant importance toward the performance of photovoltaic devices.