Fig. 1: A liquid to solid phase transition of PEO in a water solution.
From: Flow-induced crystallisation of polymers from aqueous solution
A schematic representation of the phase transition under flow (flow-induced crystallisation of PEO in water). In the quiescent state a PEO chains are coiled globular molecules (PEO segments—ball representation, water molecules—stick representation), surrounded by a protective sheath of water molecules (blue dashed lines), which prevents PEO segments from polymer intermolecular interactions. Crystallisation is prevented by this hydration sheath even when cooled far below the melting point. However, when flow is applied, b molecules become oriented and stretched along the flow direction leading to breakage of hydrogen bonds (dotted lines) and rupture of the hydration shell. Stretched segments of desolvated PEO, similar in orientation and conformation to that of a PEO crystal are exposed to each other. Following removal of water molecules from between the chains establishing polymer intermolecular interactions, c PEO chains crystallise in a helical conformation creating a solid phase.
