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Pluripotency, which is defined as a system not fixed as to its developmental potentialities, is typically associated with biology and stem cells. Inspired by this concept, we report synthetic polymers that act as a single “pluripotent” feedstock and can be differentiated into a range of materials that exhibit different mechanical properties, from hard and brittle to soft and extensible. To achieve this, we have exploited dynamic covalent networks that contain labile, dynamic thia-Michael bonds, whose extent of bonding can be thermally modulated and retained through tempering, akin to the process used in metallurgy. In addition, we show that the shape memory behavior of these materials can be tailored through tempering and that these materials can be patterned to spatially control mechanical properties.

 

This perspective offers insights from discussions conducted during the Telluride Science meeting on organic mixed ionic and electronic conductors, outlining the challenges associated with understanding the behavior of this intriguing materials class.

 

Sequential vapor doping is a vital process in controlling the electronic transport properties of semiconducting polymers relevant to opto-electronic and thermoelectric applications. Here, we employed an in situ conductivity method to determine the temporal electronic conductivity ( σ ) profile when vapor 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) doping poly(3-hexylthiophene) (P3HT) thin films held at a different temperatures. The temporal profile of σ first showed a fast exponential increase, followed by a brief linear increase until reaching a σ max , and followed by a slow decay in σ . The σ profile were correlated to structural changes through a combination UV-vis-NIR spectroscopy, X-ray scattering, and Raman spectroscopy. We find that the timing for σ max , and subsequent drop in σ of P3HT:F4TCNQ thin films corresponds to the evolution of doping in the crystalline (ordered) and amorphous (disordered) domains. Specifically, Raman spectroscopy resonant at 785 nm highlighted that the crystalline domains reached their saturated doping level near σ max and subsequent smaller level of doping occurred in regions in the disordered domains. Overall, this study emphasizes the importance of granular understanding of σ and the corresponding structural changes in the crystalline and amorphous domains.