Chain Cluster Diffusion and Network Relaxation in Poly(vinyl alcohol) and Borax Solutions
Year: 2026
Type: preprint
Abstract: The physical chemistry of poly(vinyl alcohol) (PVA) and borax solutions reflects the formation of dynamic covalent borate anion cross-links between chains. Due to the reversible linkages, PVA and borax solutions not only exhibit re-entrant phase behavior, but they also display distinct fast and slow relaxations. While the fast regime corresponds to single chain and small cluster diffusion, the slow regime transitions from large cluster diffusion to reversible network relaxation as the borax concentration increases. Because these relaxation processes are highly sensitive to the solution phase behavior, multiple complementary techniques are needed to paint a comprehensive picture of the system dynamics. In this work, we use a combination of 1 H nuclear magnetic resonance diffusion ordered spectroscopy ( 1 H NMR DOSY), dynamic light scattering, and small amplitude oscillatory shear to study the dynamics of PVA and borax solutions across their reentrant phase transitions. In the clear liquid and phase separated windows, increasing borax concentration causes the average size and breadth of the PVA clusters to increase. In the clear gel window, the chains percolate into a dynamic network that becomes invisible to the 1 H NMR DOSY measurements. Increasing temperature alters the mechanism of the slow relaxation process of the clear gel. Through this multi-modal approach, we find that the characteristic sizes, relaxation times, and activation energies of the fast and slow relaxation regimes span several orders of magnitude.
Source: ChemRxiv
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7208771352