Reprocessable and chemically recyclable poly(acylhydrazone–imine) covalent adaptable networks with enhanced mechanical strength and creep resistance

Abstract

A room temperature chemically recyclable poly(acylhydrazone–imine) covalent adaptable network with high mechanical strength and creep resistance was constructed by designing synergetic hydrogen bonds and acylhydrazone bonds in a single polymer network.

Covalent Adaptable Networks Containing Nitrogen-Coordinated Boronic Ester and Imine Bonds

“…For example, the τ* of EPPA 10:6 decreased from 95.4 to 14.9 s as the temperature increased from 100 to 130 °C (Figure c). To further explore the dynamic behavior of the EPPA CANs, the activation energies ( E a ) of the polymer networks were calculated using the Arrhenius equation: , τ * false( T false) = τ 0 exp false( E a / R T false) where τ* is the time when the modulus relaxes to 1/e, τ 0 is the Arrhenius prefactor, T is the experimental temperature, and R is the gas constant. As shown in Figure d, the E a values of EPPA 10:4 , EPPA 10:5 , and EPPA 10:6 were 50.5, 54.3, and 70.4 kJ mol –1 , respectively.…”

“…This decrease in storage modulus of EPPA CANs can be attributed to the dynamic breakage of imine bonds under heating at high temperatures. Then, the cross-linking density ( V e ) of the EPPA CANs was calculated from the plateau modulus in the storage modulus curves according to the classical theory of rubber elasticity using the following equation: , V e = E / 3 R T where E is the plateau modulus in the rubbery state at T g + 60 °C, R is the gas constant, and T is the Kelvin temperature of T g + 60 °C. As shown in Table , with an increase in the molar ratio between 4-PBA and β-amino diol groups in EPNH, E ′ increased from 3.0 to 7.8 MPa in the rubbery state and V e simultaneously increased from 289.2 to 726.7 mol m –3 .…”