2D Conjugated Polymers from Stable Free Radical Building Blocks
Abstract
Graphene, a single carbon thick layer of graphite, has attracted an enormous attention from solid state physicists, materials scientists and electronic engineers, due to its special electronic properties stemming from two-dimensional (2D) electron confinement. However, its zero band gap and lack of means for chemical modification (without saturating ~-bonds) severely limits possible applications in semiconducting industry. The OBJECTIVE of this proposal is to develop Òorganic graphenesÓ, i.e. 2D polymers built with tailored ~- functional building blocks. This could provide solution to both of above problems, and open the doors to a wide variety of electronic materials with endless spectrum of applications. While a number of 2D organic polymers have recently been investigated around the world, no convincing evidence of the ÒspecialÓ properties related to their 2D structure have been reported. This should not be too surprising considering the limited electronic communication/electron delocalization brought about by the chosen organic building blocks and the mode of their linking. A SOLUTION proposed here is based on the use of open-shell stable radicals as a basic building blocks connected in a 2D net via tailored covalently bonded links. This type of materials has been speculated about for over 50 years, but the possible approach to its synthesis have not been available until most recently. The expected spin-coupling effects between the radical building blocks will lead to either low-spin highly-delocalized system (low band-gap semiconductors) or high-spin materials with potential ferromagnetic ordering, depending on the type of the link between the monomer units. The potential applications include ultra-fast thin film transistors, organic magnets, magnetoresitor devices, sensors, etc. Achieving these objectives will involve solving several technical challenges: 1) synthesis of stable free radical monomers with reactive functional groups; 2) establishing and optimizing approaches to 2D ordered polymerization of these monomers under dynamic equilibrium, based on the known and new polymerization reactions; 3) controlling the interaction between the unpaired electrons by the choice of the linker group (boroxine; arylimines; arylenamines; direct aryl-aryl bonds); 4) preparation of individual 2D polymer sheets, by either defoliation of bulk material (stacked sheets) or surface-confinded polymerization; 5) characterizing the electronic/magnetic properties of the obtained 2D polymers by a combination of optical/electron paramagnetic resonance spectroscopy, electrochemical doping/dedoping, magnetic susceptibility and charge transport measurements.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 11, 2018
- Source ID
- W911NF1710126
Entities
People
- Dmitrii F Perepichka
Organizations
- Army Contracting Command
- McGill University
- United States Army