A metal-free approach combining sulfoxide-directed metal-free C–H cross-couplings with tuneable heterocyclizations and dimerizations allows expedient access to important organic materials.
Controllable p-type doping of both poly(3-hexylthiophene) (P3HT) and poly(triarylamine) (PTAA) organic field effect transistors (OFETs) was achieved by immersing complete top-contact OFETs in a solution of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) in acetone. As this method is applied to complete devices, it has a greater utility than methods involving doping of the solution prior to film deposition as it allows separation of the device processing and doping steps, facilitating the use of optimal processing conditions at each stage. It was found that by varying immersion time and the concentration of the dopant solution, it was possible to vary the threshold voltage for a P3HT OFET by over 30 V. Although PTAA devices are less sensitive to oxidation by F4-TCNQ than OFETs using P3HT, they can also be controllably doped by this method up to a threshold voltage of +12 V.
Using an electrostatic-based super inkjet printer we report the high-resolution deposition of polyelectrolyte macroinitiators and subsequent polymer brush growth using SI-ARGET-ATRP. We go on to demonstrate for the first time a submicron patterning phenomenon through the addition of either a like charged polyelectrolyte homopolymer or through careful control of ionic strength. As a result patterning of polymer brushes down to ca. 300 nm is reported. We present a possible mechanistic model and consider how this may be applied to other polyelectrolyte-based systems as a general method for submicron patterning.
The study focuses on the development of a new family of layer-by-layer coatings comprising Nafion, lysozyme and chitosan to address challenges related to microbial contamination. Circular dichroism was employed to gain insights on the interactions of the building blocks at the molecular level. Quartz crystal microbalance tests were used to monitor in real time the build-up of multilayer coatings, while atomic force microscopy, contact angle and surface zeta potential measurements were performed to assess the surface characteristics of the multilayer assemblies. Remarkably, the nanocoated surfaces show almost 100% reduction in the population of both Escherichia coli and Staphylococcus aureus. The study suggests that Nafion based synergistic platforms can offer an effective line of defence against bacteria, facilitating antimicrobial mechanisms that go beyond the concept of exclusion zone.
This
study presents preliminary experimental data suggesting that
sodium 4-(pyrene-1-yl)butane-1-sulfonate (PBSA),
5
, an
analogue of sodium pyrene-1-sulfonate (PSA),
1
, enhances
the stability of aqueous reduced graphene oxide (RGO) graphene dispersions.
We find that RGO and exfoliated graphene dispersions prepared in the
presence of
5
are approximately double the concentration
of those made with commercially available PSA,
1
. Quantum
mechanical and molecular dynamics simulations provide key insights
into the behavior of these molecules on the graphene surface. The
seemingly obvious introduction of a polar sulfonate head group linked
via an appropriate alkyl spacer to the aromatic core results in both
more efficient binding of
5
to the graphene surface and
more efficient solvation of the polar head group by bulk solvent (water).
Overall, this improves the stabilization of the graphene flakes by
disfavoring dissociation of the stabilizer from the graphene surface
and inhibiting reaggregation by electrostatic and steric repulsion.
These insights are currently the subject of further investigations
in an attempt to develop a rational approach to the design of more
effective dispersing agents for rGO and graphene in aqueous solution.
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