To date, (n, m) single-walled carbon nanotubes (SWNTs) cannot be selectively synthesized. Therefore, postprocessing of SWNTs including solubilization and sorting is necessary for further applications. Toward this goal, we have synthesized a polymer library consisting of fluorene-and carbazole-based homo-and copolymers. Variations of the connection of these aromatics together with the incorporation of further conjugated monomers give access to a broad diversity of polymers. Their ability to selectively wrap specific (n, m) species is investigated toward HiPco SWNTs raw material which contains more than 40 (n, m) species. Absorption and fluorescence spectroscopies were used to analyze SWNTs/polymer suspensions. These results provide evidence for selective SWNTs/polymer interactions and allow a more detailed assessment of polymer structure− property relationships, thus paving the way toward custom synthesis of polymers for single (n, m) SWNTs extraction.
Monodisperse and size-controlled spherical polymer particles were synthesized by in situ photopolymerization of O/W monomer emulsions. Monomer droplets were produced without surfactant or pretreatment at a needle tip in a simplified axisymmetric microfluidic device. The effect of the viscosity of the continuous phase on the particle size was studied. The system operated in the dripping mode, at a low Reynolds number. A dimensionless master curve describes the particle diameter as a function of the needle inner diameter as well as velocity and viscosity ratios of continuous and dispersed phases. An empirical law predicts the particle size. The normalized particle diameter depends upon the ratio of the capillary numbers of continuous and dispersed phases with an exponent equal to -0.22.
n‐Type‐doped polymers are key elements to fabricate all‐polymer thermoelectric generators but they are challenging to produce. Herein, a new strategy is proposed, which is based on polarity switching upon doping of a donor–acceptor (D–A) copolymer based on diketopyrrolopyrrol (DPP) and quintethiophene (5T) with FeCl3. Polarity switching from p‐type to n‐type is observed upon increasing the doping concentration of FeCl3. An analysis based on nonmonotonic density of states is proposed, which accounts for the main experimental trends and demonstrates that the polarity switch is governed by the electronic band filling that is determined by the dopant concentration. The influence of the curvature of the density of states is in addition discussed and a complete description of the doping induced transport regimes is proposed. This polarity switching depends on the molecular weight Mn of the polymer and shifts to higher FeCl3 concentrations with increasing Mn. This behavior is attributed to the change of the width of the density of states with Mn. The combination of polarity switching and alignment is a means to produce n‐type‐like oriented and conducting polymers with enhanced power factors up to 10 µW K−2 m−1 along the chain direction.
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