Imparting low dielectric constant and high toughness to polyimide via physical blending with trifluoropropyl polyhedral oligomeric silsesquioxane

Abstract

Polyhedral oligomeric silsesquioxane (POSS) is commonly used to lower the dielectric constant of polyimide (PI), but the toughness generally deteriorates.In this paper, trifluoropropyl POSS (FPOSS) is surprisingly found to impart superior dielectric constant and toughness to PI, even though the phase separation and aggregation of FPOSS are observed due to the thermodynamical immiscibility between FPOSS and PI. The dielectric constant of FPOSS/PI with 2.0 wt% FPOSS is reduced to 2.47 from 3.17. Furthermore, the tensile energy to break of FPOSS/PI is unexpectedly increased to 10.2 MJ/m 3 from 3.3 MJ/m 3 , indicating the great improvement in toughness. The toughening mechanism is ascribed to the debonding of FPOSS aggregates from PI matrix with a void growth during tensile test. Meanwhile, lateral coalescence of the voids is avoided due to the adequate inter-aggregate distance when the width of the ligaments between the aggregates decreases with elongation of matrix.

Superhydrophobic and Stretchable Carbon Nanotube/Thermoplastic Urethane-Based Strain Sensor for Human Motion Detection

“…In the FTIR spectra of PDA/CNT/POSS-TPU and CNT/F-TPU, characteristic peaks at 2800−3000 cm −1 attributed to the stretching vibration of C−H, and the peaks at 1030 and 1067 cm −1 attributed to the Si−O−Si stretching vibration from the silicon core of POSS. 33,34 The peak around 1100 cm −1 is due to the C−F stretching vibration. 35 In the XRD patterns of PDA/CNT/POSS-TPU and CNT/F-TPU (Figure 2g), the typical peaks assigned to POSS are clearly observed.…”

The Recent Advances of Polymer–POSS Nanocomposites With Low Dielectric Constant

“…The intermolecular hydrogen bonding in the material hindered the rotation of polymer chains and could delay the aggregation of POSS nanoparticles, improving the dispersibility of the nanoparticles. [ 118 ] This, in turn, enhanced the dielectric performance, thermal stability, and mechanical properties of the material. For fluorine atoms, which have a high electronegativity, the introduction of fluorine‐containing groups has the effect of reducing the polarity of molecules or polymers, thereby helping to lower the dielectric constant of the dielectric.…”

Research Advances of Porous Polyimide—Based Composites with Low Dielectric Constant

“…Interestingly, the transparent PI composite films displayed enhanced atomic oxygen-resistant properties, showing a high prospect for antenna substrates in aerospace applications. Chen et al [ 78 ] employed trifluoropropyl POSS to modify PI film and the dielectric constant of POSS/PI with 2.0 wt.% POSS decreased to 2.47 from 3.17 (pure PI) at 10 MHz and the corresponding dielectric loss was reduced to 0.0089 from 0.011 due to the hollow structures in the POSS molecule and the existence of fluorine substituents. He et al [ 79 ] prepared POSS containing a hierarchical porous structure by the self-assembly of water droplets and utilized it as a coating for the flat PI film.…”