Fig. 4: Stress relaxation and self-healing tests of the Ph polymer.
From: Heterocycle-based dynamic covalent chemistry for dynamic functional materials
a Stress relaxation tests for the Ph polymer (M(A3) = 692 g mol−1) at different temperatures by dynamic mechanical analysis, with the results fitted by an exponential equation. The time when St/S0 reached 1/e was defined as the relaxation time (τ). b Arrhenius plot to determine the activation energy (Ea) of stress relaxation (coefficient of determination R2 = 0.991). c Comparison of the Ph polymer with reported DCC-based materials in terms of the Ea of stress relaxation. d Photos and microscopic observations of the self-healing (top) and healing under pressure (~0.1 MPa, bottom) of the Ph polymer at room temperature (25 °C); dashed box: the position of the crack; scale bar of photos = 0.5 cm; scale bar of microscopic images = 500 μm. e Mechanical stiffness characterization of samples after different durations of self-healing and corresponding mechanical recovery rate calculated from the breaking stress value (inset).
