Phase-separation kinetics in dynamically asymmetric binary fluids: Viscoelastic effects in polymer solutions

Abstract

The strong asymmetry in molect, lar dynamics between the two compc, nents of a binary mixture leads to a strong kinetic cot, piing between the stress field and the order parameter (concentration). which significantly aft'cots the phase separation. A polymer solt, tion. as a typical example of dynamically asymmetric mixtures, behaves as a gel in the initial stage of phase separalion Ibr a deep qt,ench, while it behaves z,s a simple viscous fluid in the final stage. In the intermediate stage, the rclaxational rmture of the viscoelastic eft;cot plays ~,n importartt role in patterrt evolution, which violates the self-similarity of the growing pattern. To understand the phenonlenzl Zl concept of dl'nami,." .~'I'IHDIt'IFV should be introduced in addition to the static composition symmetry,.

Alteration of Microstructure in Biopolymeric Hydrogels via Compositional Modification of Resilin-Like Polypeptides

“…By employing the phase diagram (Figure A) as a guide, the conditions under which the RLP-W-4Ac solution will phase separate can be selected and the microstructure generated during LLPS can be arrested during photo-cross-linking. In order to generate more stable emulsions, a heating–cooling protocol (Figure B) was developed on the basis of the literature precedent showing that such a treatment can favor the formation of bicontinuous structures that jam the system and delay the phase separation. − To assess such effects in the RLP hydrogels, the RLP-W-4Ac emulsions were warmed above the transition temperature (80 and 60 °C) and immediately cooled for 30 s in an ice bath. The final temperatures were determined from the cooling profiles (Figure S11) and were 19.5 ± 0.95 and 15.1 ± 0.5 °C, respectively.…”

“…Two types of morphologies can be observed in Figure C for RLP-W-4Ac (20 wt %, 80 °C): buffer spherical domains, characteristic of nucleation and growth (black circles in Figure C) dispersed in an RLP-rich matrix (white signal surrounding the black circles in Figure C), and inside the large buffer domain, a dispersed RLP-rich network with a structure akin to that of spinodal decomposition induced by the quenching process. − RLP-W-4Ac (20 wt %, 60 °C) resulted in different morphological features: spherical RLP-rich domains dispersed in the RLP network (Figure E), perhaps formed by a percolation-to-cluster mechanism where bicontinuous domains break, forming stable spheres. − The bicontinuous networks shown in Figure C,E can be better observed in the 3D projection of the complete z-stack in Figure S12. In contrast, both 80 and 60 °C RLP-F-4Ac 20 wt % samples show no microstructure at all (Figure D,F), which was expected owing to the lack of a UCST transition for this construct.…”