Tröger’s Base (TB)-Based Polyimides as Promising Heat-Insulating and Low-K Dielectric Materials

Abstract

The correlations between the molecular structures of four Troger's base (TB)-based polyimides (PIs) and two non-TB containing analogues and physical properties including thermal conductivity (λ) and dielectric properties both at low and high frequencies were investigated in detail. The TB-based PI films exhibited low dielectric constants (D k = 2.25−2.80) at 10 GHz. They possessed much lower λ values (0.035−0.145 W/mK) compared to the commercial PI Kapton (0.240 W/mK). The influences of incorporating TB units into chain backbones on aggregation structures and physical properties of PIs were identified. Incorporating TB units into chain backbones effectively reduced the degree of chain orientation and increased fractional free volume, leading to both low D k and low λ values for the resulting PI films. Also, introducing TB units enhanced molecular weights, toughness, and glasstransition temperature (T g ) of the resulting PIs. Therefore, the TB-based PIs can be promising heat-insulating and low-k dielectric materials.

Increasing Twist Rigidity to Prepare Polyimides with Low Dielectric Constants and Dissipation Factors over a Wide Temperature Range

“…Compared to that of 6FDA-mPDA, the thermal conductivity of 6FDA-GB was reduced by about 60% to 0.112. This indicates its potential application in thermal resistance. , The cast PI films also have high modulus (>2.2 GPa) and tensile strength (>70 MPa) (Figure c).…”

“…This indicates its potential application in thermal resistance. 48,49 The cast PI films also have high modulus (>2.2 GPa) and tensile strength (>70 MPa) (Figure 8c).…”

Low dielectric constant and highly intrinsic thermal conductivity fluorine‐containing epoxy resins with ordered liquid crystal structures

“…TFSAEy/DDM with a relatively higher content of biphenyl crystalline elements shows a relatively higher degree of micro‐order (Figure 5D4), in favor of decreasing ε and tan δ . Compared with TFSAEy, the liquid crystal temperature (113.5°C–127.2°C) of TFGAEy does not match the temperature of the curing reaction between TFGAEy and DDM (160.2°C–198.7°C), which would destroy the ordered π–π stacking structure of biphenyl units by the strong molecular thermal motion, increasing ε and tan δ 53 …”

“…Compared with TFSAEy, the liquid crystal temperature (113.5 • C-127.2 • C) of TFGAEy does not match the temperature of the curing reaction between TFGAEy and DDM (160.2 • C-198.7 • C), which would destroy the ordered π-π stacking structure of biphenyl units by the strong molecular thermal motion, increasing ε and tan δ. 53 Besides, the corresponding ε and tan δ decrease with increasing frequency. This is because the electron, atomic and orientation polarization can keep up with changes in the external electric field at low frequencies.…”

Soluble Polyimides Containing Benzocyclobutene Moieties: Synthesis, Cross-Linking Behavior, and Physical and Gas Transport Properties

“…The signals located at 3.14−3.16 ppm and 6.93−8.03 ppm are attributed to protons in the BCB quaternary and aromatic rings, respectively. As shown in Figure 2b, the absorption bands at 1778 and 1714 cm −1 correspond to symmetric and asymmetric imide carbonyl stretching vibrations, respectively, 34 whereas the absorption band at 1370 cm −1 is attributed to imide C−N stretching vibrations. 34 Moreover, the absorption bands at 1468 (in-plane bending vibration) and 2923 cm −1 (stretching vibration) belong to the C−H vibration of the BCB fourmembered ring.…”