Organosoluble and transparent cardo polyimides with high T_g derived from 9,9-bis(4-aminophenyl)xanthene

Abstract

9,9-Bis(4-aminophenyl)xanthene (BAPX) was prepared simply and effectively via one-pot, two-step procedure using xanthenone and aniline as main substrates. The monomer BAPX was reacted with six aromatic dianhydrides in N, N-dimethylacetamide (DMAc) to yield the corresponding polyimides (PIs) via the poly(amic acid) precursors and subsequent thermal or chemical imidization. The resulting PIs exhibited good thermal stability with glass transition temperatures of 308–348°C, initial decomposition temperatures of 470–510°C, 10% weight loss temperatures of 540–565°C, and char yields of 55–59% at 800°C in nitrogen, respectively. All polymers were amorphous and readily soluble in organic solvents such as N-methyl-2-pyrrolidone and DMAc. The PI films had tensile strengths of 71–92 MPa, tensile moduli of 1.91–2.35 GPa, and elongations at break of 5–13%. Meanwhile, these polymer films also had high optical transparency with a cutoff wavelength in the range of 367–415 nm, lower dielectric constants (3.02–3.34 at 10 MHz), and low water uptake of 0.30–0.52%.

Research Progress and Application of Polyimide-Based Nanocomposites

“…Generally, a temperature above T g is required for complete imidization [ 78 ]. The molecular chains start to move at a temperature above T g , benefiting from increasing the packing density and obtaining higher T g [ 79 , 80 , 81 ]. The molecular motion facilitates chains’ disorder, leading to higher CTE and poorer transparency [ 82 , 83 ].…”

Synthetic strategies for highly transparent and colorless polyimide film

“…The polymer molecular chains are capable to move at the temperature higher than T g , which is conducive to improving the packing density. PIs with higher packing densities generally possess higher T g s 86–88 . However, the motion of molecular chains promotes the disorder of their arrangement, resulting in higher CTE 89–91 …”

“…Chemical imidization process can lower the heat treatment temperature of PI films below T g , so that it can avoid oxidation, embrittlement, crosslinking at high temperature, and reduce CTE and packing density 87 . The decrease of packing density helps improve PI film transmittance 89,91 .…”

“…A diamine, 9,9‐bis(4‐aminophenyl)xanthene (BAPX, Figure 12a), containing a xanthene group as a pendant substituent was synthesized and used for polymerization with some dianhydrides such as 6FDA 87 . It is found that the crystallinity of polymers decreases, while the optical transparency, solubility and thermal properties are improved after the introduction of xanthene.…”

High-performance polyimides based on pyridine and xanthene pendant groups; synthesis, characterization, photoactivity, thermal, antibacterial, and Cr(VI) ion adsorption properties

“…These results in increasing the solubility characteristics without affecting thermal and mechanical properties. 24 –27 It has also been reported that the pyridine heterocyclic ring will improve processability and solubility of PIs due to its symmetry, aromaticity, and polarizability resulting from the heteroatoms such as nitrogen atoms. 11,28…”