Frustrated Crystallization in the Coupled Viscoelastic Phase Separation

Abstract

The interplay between crystallization and phase separation has been intensively studied recently. In this study, we extended the research into a dynamically asymmetric blend composed of amorphous poly­(methyl methacrylate) (PMMA) and crystalline poly­(ethylene oxide) (PEO). The large dynamic asymmetry induces network stress in concentration growth. We find that crystallization is seriously frustrated when it couples with a simultaneous viscoelastic phase separation. In a single quench experiment, normal spherulites grew in a limited temperature range when crystallization was faster, while crystallization was frustrated at deep quenches when phase separation was faster. In a double quench experiment, crystallization was more difficult to occur after the prior phase separation at a higher temperature. The calorimetric results indicated that both melting temperatures and enthalpies of crystallization decreased in the coupled viscoelastic phase separation. We propose that it is the network stress in the concentration growth that leads to the frustration of crystallization.

Confined and Directed Polymer Crystallization at Curved Liquid/Liquid Interface

“…c) Type 2 phase diagram detailing eight paths that can be taken to study LLPS and crystallization. Reproduced with permission . Copyright 2012, American Chemical Society.…”

“…Reproduced with permission. [36] Copyright 2012, American Chemical Society. d) Schematic of heterogeneous nucleation occurring at the two-phase interface.…”

Morphological evaluation and phase behavior of PVDF/PEO blends in the presence of graphene nanoplatelets through rheological measurements

“…From another point of view, presence of the GNPs modified the rheological properties of the PVDF and PEO and resulted in convergence of their viscoelastic properties to one another as it was implied in the Rheologically Determined Phase Diagram section. This phenomenon reduces the effect of viscoelastic phase separation (VPS) in the PVDF/PEO blends that originates from the dynamic asymmetry of components of the blend …”

“…This phenomenon reduces the effect of viscoelastic phase separation (VPS) in the PVDF/ PEO blends that originates from the dynamic asymmetry of components of the blend. 46,47 SEM images were used to morphologically confirm the attained phase diagram. As an example, morphological evolution of the 70/30/0.5 sample upon heating and coalescence process from the miscible zone to two-phase region is presented in Figure 13.…”

Influence of thermal history on crystalline morphologies of isotactic polypropylene in its miscible blends with polybutene‐1

“…Further studies indicate that the extent of phase segregation depends on the relation between crystallization rate of the high T m component and the chain mobility of the low T m component . Meanwhile, primary nucleation of crystallization can be assisted by concentration fluctuation, especially at the interface boundaries of phase separated domains …”