Fibrillar gel self-assembly via cononsolvency of amphiphilic polymer

Hypothesis: Polymer with amphiphilic repeating units bathed in the mixed binary solvent can exhibit fibrillar formation and gelation via cononsolvency effect. Mechanism of gelation will be highly dependent on the solvent's interactions and morphology of the resulting fibrillar gel can be fine-tuned by changing binary solvent composition. Experiments: Amphiphilic homopolymers dissolved in a mixture of two solvents with different affinities to monomeric units and to each other were modeled using dissipative particle dynamics. Morphological transitions in dilute and concentrated solutions were investigated depending on the solvent-cosolvent interaction and binary solvent composition. Fibrillar gel structure was characterized via calculation of fibril's and pore's diameters. Findings: Amphiphilic macromolecules can combine into fibrils and form a gel as a result of the cononsolvency caused by microsegregation with one or both components of a binary solvent. In the former, the fibrils are loose, in the latter -dense. For dilute solution, state diagram in terms of solvent/cosolvent miscibility and binary solvent composition is constructed and two regions with different fibrillar gels are distinguished. For concentrated solution, the conditions, governing fibrillar diameter, pore size, number and functionality of branching points, are highlighted. These findings would be useful for the controlling synthetic matrix morphologies in the tissue engineering. (c) 2022 Published by Elsevier Inc.