Vanillin-based degradable thermosets with superior dielectric properties via regulation of imine cross-linked structure

Developing cross-linked polymers with both low dielectric constant and degradability for microelectronics and sustainability remains a challenge. Herein, a new fluoro-containing dialdehyde monomer (VF) derived from vanillin was synthesized, which was then cross-linked with a tris (2-aminoethyl) amine (TREN) and different diamines (4, 4 ′ -methylenebis (cyclohexylamine) (PACM), 4, 4 ′ -diaminodiphenylmethane (DDM) and 1, 6-hexamethylenediamine (HMDA)) to give three polyimines thermosets, namely VFT-P, VFT-D and VTF-H, respectively, showing controlled comprehensive properties through regulation of imine cross-linked structures. Properties-function relationship of these polyimines was systematically studied and focused mainly on revealing the degradation process and the mechanism of the degradability of polyimines. The results indicated that among these polyimines, VFT-P exhibited superior conventional properties and acid resistance due to its appropriate reactivity, cross-linked density, rigid non-conjugated Schiff base structures, and high free volume. The storage modulus, glass transition temperature, transmittance, and tensile strength of VFT-P polyimines could reach 3.40 GPa, 134 °C, > 97% (at 500–800 nm) and 62.47 ± 3.65 MPa, respectively. Besides, a low dielectric constant of 2.96 at 100 MHz and superior degradability was achieved. This study introduces a facile and effective design strategy to achieve the compatibility of target properties and also offers a potentially sustainable alternative to conventional cross-linked dielectric polymers. Graphical abstract