Cage-Enriched Macromolecules: Exploring New Dimensions in Materials Science

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Synthetic polymers are found in nearly all modern materials such as plastics, resins, coatings, elastics, and composites in nearly all aspects of daily life. The structure of monomers used to obtain such macromolecules dictates the microstructure of the resulting polymers by controlling how they can fold or pack together, which ultimately imparts different properties to materials at the macroscale. Polymers have traditionally been made from linear monomers, e.g. polyethylene, and ring-shaped-containing monomers, e.g. Kevlar. The latter are more rigid than the former. This translates into valuable mechanical properties such as their high mechanical strength. A third polymer microstructure, poly(cage)mers, can also be envisioned, being a result of connecting 3-dimensional cages as monomers. Despite several decades of efforts in this area, only two families of high-molecular weight poly(cage)mers have thus far been prepared and with great difficulty and poor efficiency: poly(propellane) and poly(adamantane). This is mainly due to difficulties in the development of viable synthetic methods to obtain stable and soluble/processable poly(cage)mers.This proposed research brings together three highly motivated early career researchers from three institutions (Dalhousie, UQAM, and UdeM) and two provinces (Quebec and Nova Scotia) to tackle challenges associated with accessing such fundamentally interesting and practically potentially advanced polymeric materials. We propose to use readily accessible phosphorus-nitrogen (PN) cages as a vehicle to explore new parameter space in materials science and discover emergent properties that are not available to analogous carbon-based (organic) materials. Since cages are rigid materials, containing them into a polymer chain might exhibit enhanced resistance to deformation, and since cages are mostly empty, materials derived from them should exhibit low density. Thus, we hypothesize that cage-dense materials will combine low density with high rigidity, making them very valuable for applications in the transportation, packaging, and aero-space industry.