- R. Zhang, T. Yan, B.-D. Lechner, K. Schröter, Y. Liang, B. Li, F. Furtado, P. Sun, K. Saalwächter.
Heterogeneity, Segmental and Hydrogen Bond Dynamics, and Aging
of Supramolecular Self-Healing Rubber.
Macromolecules 46, 1841-1850 (2013).
In recent years, self-healing materials have attracted increasing
attention due to their potentially spontaneous self-repairing ability after
mechanical damage. Here, we focus on a supramolecular self-healing rubber
based on fatty acids following the work of Leibler and co-workers. We study the
heterogeneous network structure and hydrogen bond dynamics as well as its
significant aging properties using several experimental techniques. NMR
experiments reveal that the rubber is basically a two-component system, with a
∼ 85% fraction of material rich in hydrogen-bonded structures and associated
aliphatic moieties, undergoing a glass transition just below ambient temperature,
and the other one being comprised of more mobile aliphatic chains. Changes in
the IR bands corresponding to the NH bending and CO stretching vibrations show that water in the rubber not only takes the
role of a plasticizer, reducing the glass transition temperature of the main component, but also is involved in changes of the
hydrogen-bonding network. On the basis of shear rheology experiments and proton low-field NMR, we deduce that the rubber
undergoes irreversible chemical cross-linking reactions at temperatures above 110 °C, going along with a weakening of its selfhealing