Double dynamic hydrogels formed by wormlike surfactant micelles and cross-linked polymer

Abstract

Hypothesis: Interpenetrating networks consisting of a polymer network with dynamic cross-links and a supramolecular network allow obtaining hydrogels with significantly enhanced mechanical properties. Experiments: Binary hydrogels composed of a dynamically cross-linked poly(vinyl alcohol) (PVA) network and a transient network of entangled highly charged mixed wormlike micelles (WLMs) of surfactants (potassium oleate and n-octyltrimethylammonium bromide) were prepared and studied by rheometry, SANS, USANS, cryo-TEM, and NMR spectroscopy. Findings: Binary hydrogels show significantly enhanced rheological properties (a 3400-fold higher viscosity and 27-fold higher plateau modulus) as compared to their components taken separately. This is due to the microphase separation leading to local concentrating of PVA and WLMs providing larger number of polymer–polymer contacts for cross-linking and longer WLMs with more entanglements. Such materials are very promising for the application in many areas, ranging from enhanced oil recovery to biomedical uses.