One-dimensional patchy nanostructures are interesting materials due to their excellent interfacial activity and their potential use as carrier for functional nanoparticles. Up to now only wormlike crystalline-core micelles (wCCMs) with a nonfunctional patchy PS/PMMA corona were accessible using crystallization-driven self-assembly (CDSA) of polystyrene-block-polyethylene-block-poly(methyl methacrylate) (SEM) triblock terpolymers. Here, we present a facile approach toward functional, patchy wCCMs, bearing tertiary amino groups in one of the surface patches. The corona forming PMMA block of a SEM triblock terpolymer was functionalized by amidation with different N,N-dialkylethylenediamines in a polymer analogous fashion. The CDSA of the functionalized triblock terpolymers in THF was found to strongly depend on the polarity/solubility of the amidated PMMA block. The lower the polarity of the amidated PMMA block (increased solubility), the higher is the accessible degree of functionalization upon which defined, well-dispersed wCCMs are formed. Interestingly, also the structure of the patchy corona can be tuned by the composition/chemistry of the functional patch, giving rise to spherical patches for R = methyl, ethyl and rectangular patches for R = isopropyl. Patchy wCCMs were successfully used as template for the selective incorporation of Au nanoparticles within the amidated corona patches, showing their potential as versatile platform for the construction of functional, mesostructured hybrid materials.
Conjugated polymers, especially their second generation with a donor–acceptor alternating structure, have promising properties. These are suitable for two emerging fields, thermoelectrics and bioelectronics, if appropriate structural designs are implemented. This review aims to give a perspective for the potential and challenges of novel conjugated polymers in such applications. In particular, the aspects of synthetic design and the consequences of modifications of the chemical structure on the charge transport in selected second‐generation conjugated polymers are reviewed. By understanding the effects of structural motifs on the overall material properties, polymers can be specifically tailored for the respective application. The basics of charge transport measurements are briefly summarized, as the charge transport plays an important role for thermoelectrics as well as for bioelectronics. In particular, the correlation between the reported charge carrier mobility values and the structural design of the polymers is reviewed. Examples of the application of second‐generation conducting polymers in thermoelectrics and bioelectronics are shown to demonstrate the current state of research. Finally, the prospect of a purposeful design of new materials for these two emerging fields is discussed.
Doped semiconductor polymers are gaining huge interest as materials in future energy conversion applications such as low-power polymeric thermoelectrics (TEs), because they are light weight, flexible, printable, and suitable for large area applications like wearable technologies. [1-4] The basic challenge in TE, however, lies in efficient doping of the organic semiconductors (OSCs), because OSCs have extremely low intrinsic charge carrier concentrations and hence very low electrical conductivities in the range of 10 −6 to 10 −12 S cm −1. Molecular doping, [5] commonly used to increase the electrical conductivities of OSCs, involves the addition of a redox active organic or inorganic molecule as dopant. These dopants are capable of accepting (for p-type doping) or donating electrons to OSCs (for n-type doping), thereby generating free holes or electrons in OSCs. For p-type doping, acceptor dopants such as I 2 , [6] FeCl 3 , [7] molybdenum tris(1,2-bis(trifluoromethyl) ethane-1,2-dithiolene) (Mo(tfd) 3), [8] tetrafluorotetracyano-quinodimethane (F 4 TCNQ) and
Chemical doping is a vital tool for tuning electronic properties of conjugated polymers. Most single electron acceptors used for p-doping necessitate high dopant concentrations to achieve good electrical conductivity. However, high-molar doping ratios hamper doping efficiency. Here a new concept of using multielectron acceptor (MEA) salts as dopants for conjugated polymers is presented. Two novel MEA salts are synthesized and their doping efficiency towards two polymers differing in their dielectric properties are compared with two single electron acceptors such as NOPF 6 and magic blue. Cutting-edge methods such as ultraviolet photoelectron spectroscopy/X-ray photoelectron spectroscopy (XPS), impedance spectroscopy, and density of states analysis in addition to UV-vis-NIR absorption, spectroelectrochemistry, and Raman spectroscopy methods are used to characterize the doped systems. The tetracation salt improves the conductivity by two orders of magnitude and quadruples the charge carrier concentration compared to single electron acceptors for the same molar ratio. The differences in charge carrier density and activation energy on doping are delineated. Further, a strong dependency of the carrier release on the polymer polarity is observed. High carrier densities at reduced dopant loadings and improved doping efficacies using MEA dopants offer a highly efficient doping strategy for conjugated polymers.
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