Thermally induced suppression of interchain interactions in dilute aqueous solutions of conjugated polyelectrolyte rotaxanes and their analogues

Abstract

approx. 250 words)We use steady-state and nanosecond time-resolved photoluminescence spectroscopy to investigate the evolution of packing interactions in dilute solutions of a sulfonated poly(diphenylenevinylene) lithium salt and its cyclodextrin-threaded polyrotaxanes as a function of the threading ratio (TR) when increasing the temperature from 10 to 40 °C.Contrary to the expectation of a temperature-induced increase of packing and aggregation, supported by previous Raman studies identifying a temperature-induced reduction in the inter-phenyl torsion angles, we find clear spectral (photoluminescence blue-shift and narrowing) and dynamic (shorter lifetimes and reduced weight of the long-lived components) signatures of a reduction of interchain interactions for the polyelectrolytes at higher temperatures with TR up to 1.3.

C-Si hybrid photonic structures by full infiltration of conjugated polymers into porous silicon rugate filters

“…Both observations are entirely within expectations for a conjugated polymer emitter within a context of a physical model of the luminescence originating from both strongly-bound intramolecular excitons (primary exponential) and more weakly-bound interchain states (excimers or aggregates: secondary exponential, with a longer decay time). This model is amply supported in previous literature, 46 –52 with a particularly powerful example being provided by the temporal decays of solutions of analogous materials with different and controlled degrees of aggregation, that can be fitted with the same double exponential lifetimes, by varying only the pre-exponential factors. 53…”

“…model is amply supported in previous literature, [46][47][48][49][50][51][52] with a particularly powerful example being provided by the temporal decays of solutions of analogous materials with different and controlled degrees of aggregation, that can be fitted with the same double exponential lifetimes, by varying only the pre-exponential factors. 53 Incidentally, we note that although the temporal decay dynamics of F8BT neat films are sometimes also modeled as mono-exponential (with lifetimes from 0.89 to 1.84 ns depending on wavelength, film thickness and substrate materials) given the strong preponderance of one lifetime, [54][55][56][57] fitting with a bi-exponential also for such neat films is more appropriate (e.g.…”