Rodlike/flexible polyimide composite films prepared from soluble poly(amic diethyl ester) precursors: Miscibility, structure, and properties

Abstract

Homogeneous precursor/precursor solutions with various compositions were obtained with appreciably high solid contents in N‐methyl‐2‐pyrrolidone from soluble poly(amic diethyl ester) precursors of rodlike poly(p‐phenylene biphenyltetracarboximide) (BPDA‐PDA) and flexible poly(4,4′‐oxydiphenylene biphenyltetracarboximide) (BPDA‐ODA), which are hydrolytically more stable as well as more soluble than the corresponding poly(amic acid)s being equilibrated with the constituent monomers. Both optical microscopic and light scattering measurements showed that the dried precursor blend films and resultant polyimide composite films were optically transparent, regardless of compositions and process conditions. The composite films showed a single Tg behavior. However, for the composite of 30 wt % BPDA‐PDA dispersed in the matrix of 70 wt % BPDA‐ODA, a smectic crystalline‐like aggregation of the BPDA‐PDA component was detected on wide‐angle x‐ray diffraction patterns, indicative of microscopic phase separation between the two components. This phase separation was not detected on the optical microscopy, light scattering, and dynamic mechanical thermal analysis because of their resolution limits: Optical microscopy has a resolution of submicrometers, whereas dynamic mechanical thermal analysis and light scattering have a resolution of ca. 50 Å. Therefore, it is speculated that in the composite films BPDA‐PDA and BPDA‐ODA polyimide molecules have demixed on the scale of a few nanometers. The mean long periodicity, which was estimated from the small‐angle x‐ray scattering pattern, varied from 134 to 170 Å as the content of BPDA‐ODA component increased. In addition, mechanical properties of the composite films were characterized. ©1995 John Wiley & Sons, Inc.

Adhesion of poly(4,4′-oxydiphenylene pyromellitimide) to copper metal using a polymeric primer: Effects of miscibility and polyimide precursor origin

“…For aromatic polyimides, their mechanical properties are also known to vary with the history of precursor origins used in the film formation [28][29][30] . However, the mechanical properties of PMDA-ODA PI are insensitive to its precursor origins, PAA and PAE precursors: 3.0 GPa Young's modulus and ca.…”

Fluorescence Spectroscopic and Atomic Force Microscopic Studies on the Microstructure of Polyimide/Silica-Titania Ternary Hybrid Composites

“…[1][2][3][4] Since polyimide (PI) is, however, originated from organic materials, there exists a limit for far higher performance applications in which inorganic materials are used.…”

Optical and Dielectric Anisotropy in Polyimide Nanocomposite Films Prepared from Soluble Poly(amic diethyl ester) Precursors

“…[6±11] Although optically transparent polyimide composite films were successfully prepared using soluble precursors, poly(amic acid) and/or poly(amic dialkyl ester), which are well dissolved in common weak base solvents, careful studies showed that the resulting polyimide composite films were phase segregated on a scale of several nanometers, meaning a nanocomposite rather than a molecular composite, because rigid rod-like polyimides have inherently high tendency to intermolecular chain packing and preferential in-plane molecular orientation. [9,11] In particular, these previous reports focused on the physical and structural analysis in order to study the formation of molecular composite. However, the in-plane and outof-plane optical and dielectric properties have not been investigated yet, even though this is one of major causes to make the polyimide molecular composite because the dielectric constant of the packaging or inter-dielectric layers has a huge influence on the delay of signal propagation and crosstalk between other signal lines.…”

“…This nonlinear dependence of refractive index on the composition suggests that the mixing between BPDA-PDA PI and BPDA-ODA PI is not on a molecular level but several nanometers scale. [9] Kim et al In order to investigate the relationship between this optical anisotropy and nanostructure of the composite films, high resolution x-ray diffraction patterns were measured for both in-plane and out-of-plane direction. As shown in Figure 7, the measurement was particularly focused on the characteristic angle of 11 corresponded to the (004) in-plane orientation of BPDA-PDA PI and 18.7 ± 0.2 corresponded to one of the out-of-plane amorphous halos of BPDA-ODA PI.…”

“…As shown in Figure 7, the measurement was particularly focused on the characteristic angle of 11 corresponded to the (004) in-plane orientation of BPDA-PDA PI and 18.7 ± 0.2 corresponded to one of the out-of-plane amorphous halos of BPDA-ODA PI. [9,23] As the BPDA-ODA PI content increases, the in-plane (004) peak gradually decreases whereas the out-of-plane peak at 18.7± 0.2 increases. This indicates the reduction of the inplane chain orientation and out-of-plane packing order of composite films by adding the coil-like BPDA-ODA PI.…”