Soft Matter Seminar: Gelation and Blocky Functionalization of Semi-Crystalline Polymers
Prof. Robert B. Moore, Virginia Tech University
Abstract: One of the most studied gel forming polymers is syndiotactic polystyrene (sPS). Due to the simple and precise structure of stereoregular sPS, this polymer serves as a model gel for our new post-polymerization route to form blocky copolymers. Among other semi-crystalline, engineering thermoplastics, poly(ether ether ketone) (PEEK) is of particular interest due to its high temperature thermal transitions, high crystallizability, mechanical strength, and low chemical reactivity. The effort to find new solvents capable of dissolving PEEK has produced relatively few solvent options, and only recently have we discovered solvents in which PEEK will form stable gels, hydrogels, and aerogels following solvent exchange and extraction. In this report, small angle x-ray scattering and scanning electron microscopy are utilized as complementary techniques to characterize the hierarchical nanostructure of PEEK aerogels. The form and spatial distribution of the morphological features are correlated to processing conditions such as solvent selection, drying technique (freeze-drying versus supercritical CO2 extraction), and gel concentration. Utilization of these new gels in our blocky functionalization process will also be discussed in this presentation. Finally, we will highlight our efforts to identify other gel forming polymers, such as poly(phenylene sulfide), with remarkable new morphologies.
1. Talley, S.J.; Vivod, S.L.; Nguyen, B.A.; Meador, M.A.B.; Radulescu, A.; Moore, R.B. “Hierarchical Morphology of Poly(ether ether ketone) Aerogels,” ACS Appl. Mater. Interfaces, 2019, 11, 31508-31519.
2. Noble, K.F.; Noble, A.M.; Talley, S.J.; Moore, R.B. “Blocky bromination of syndiotactic polystyrene via post-polymerization functionalization in the heterogeneous gel-state,” Polymer Chemistry, 2018, 9, 5095-5106.
3. Anderson, L.J.; Yuan, X.; Fahs, G.B.; Moore, R.B. “Blocky Ionomers via Sulfonation of Poly(ether ether ketone) in the Semicrystalline Gel State,” Macromolecules, 2018, 51, 6226-6237.