Zulkifli Ahmad

Synthetic and Structural Studies of High Performance Polymers: Crystal Structures of High Performance Aromatic Polymers Using Molecular Mechanic Modelling and Rietveld Analysis Zulkifli Ahmad

Crystal structure plays an important role in determining chemical and mechanical properties of polymers. Elucidating the crystal structure of polymers is extremely difficult particularly in obtaining a sizeable crystal for XRD analysis. This work prove the viability of computer modelling approach interfaced with simulated XRD diffraction. High-performance aromatic polymers based on the 4,4'-biphenylene, 1,3-phenylene,isophthaloyl bis(4,4'-biphenylene) and p-terphenyl units were synthesized and their crystal structures investigated. The polymers show extreme thermal stability and are insoluble in almost all organic solvents. Oligomer and polymer crystal structures were constructed using computational modelling and quantitatively compared with simulated diffraction via Rietveld Analysis. Molecular mechanics force-fields were optimised from conformational and crystal packing data determined from oligomeric analogues by X-ray single-crystal and powder diffraction methods.