Polymers do not fully solidify into well-ordered crystalline structures but rather possess a non-equilibrium microstructure that is a combination of the crystalline state and the liquid "amorphous" state -- hence the adjective semi-crystalline. In the vast majority of cases, the crystalline domains are lamellae characterized by large (µm) lateral dimensions and a small (nm) thickness which stack on top of each other leaving un-crystallized amorphous domains in between. Critically, the properties of these lamellar stacks (e.g., the average lamellar thickness or the topological features of the amorphous polymer chains) determine the thermo-physical behaviour of semi-crystalline polymers, including their elastic moduli, fluid sorption capacity and degradation rate. However, despite much investigation in the past 70 years, a unifying theory relating these properties to process parameters is still lacking. In this project we are employing computer simulation and state-of-the art theoretical tools such as self-consistent field-theory (SCFT) to investigate the interplay between thermodynamic and kinetic factors affecting the microstructure of semi-crystalline polymers with the aim of informing the design of the next generation of polymeric materials.
Figure: Schematic representation of the five types of polymer chains that can be found in the amorphous domains. From left to right: bridges, free (unentangled) loops, entangled loops, tails, and free chains.
