Vanillin-grafted organosilicon backbone polyimide resins with low dielectric, reprocessing and monomer recovery

To meet the needs of the contemporary microelectronics industry and sustainability strategies, a series of organosilicon polyimide resins (V-Si@PI-x) have been prepared by aldehyde-amine condensation reaction using vanillin as a renewable bio-based feedstock. The aldehyde-amine condensation reaction cleverly avoided highly polar amino groups and introduced fluorine-containing groups simultaneouly. So, the series V-Si@PI-x as a whole exhibited low dielectric constant (<3.1) and dielectric loss (<0.01), with V-Si@PI-5 had dielectric constant as low as 2.33 and dielectric loss as low as 0.003. The three-dimensional network in the series V-Si@PI-x featured a high density (>3800 mol/m3) of imine bonds as cross-linking points, which allowed rapid polymer network rearrangement under external pressure and heat, resulting in a reprocessing process in 8 min. In a weak acidic environment, the degradation of the series V-Si@PI-x was accomplished within 5 min, leveraging the solubility difference to effectively recover the V-D4 monomer. The series V-Si@PI-x exhibited mechanical properties superior to those of conventional silicone resins (tensile strength around 5 MPa), with tensile strength and modulus exceeding 8.4 MPa and 1 GPa, respectively. In addition, the high hydrophobicity (WCA over 110°) and low water absorption (0.35-0.96%) favored the practical application of the series V-Si@PI-x in the microelectronics industry.