Precursor Polymer Effect on Polyimide/Silica Hybrid Nanocomposite Films

Abstract

Here we report the influence of the polyimide precursor type on the surface morphology and properties of poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA PI)/silica hybrid composite films. Two types of precursor polymer were employed: poly(p-phenylene biphenyltetracarboxamic acid) (BPDA-PDA PAA) and poly(p-phenylene biphenyltetracarboxamic diethyl ester) (BPDA-PDA PES). These precursor polymers were mixed with tetraethoxysilane in the presence of HCl and H2O, which led to the precursor mixture films that contain in-situ generated silica particles via sol-gel process. Then the precursor mixture films were subject to thermal imidization to make polyimide/silica hybrid composite films. Results showed that the PAA precursor has better compatibility with silica particles, which is mainly attributed to the early making of silyl ester bonds (as evidenced by X-ray photoelectron spectroscopy) between carboxylic acid groups in the PAA and hydroxyl groups in silanol molecules. Further evidences were provided by the measurement of surface nanomorphology, crystal nanostructure, thermal/mechanical properties, and optical birefringence.

Effect of Side Groups in Polynorbornene Films for Transparent Conductive Substrates

“…In order to overcome this yellowish color, alicyclic, fluorinated, or chlorinated polyimides were attempted to diminish the formation of charge transfer complex (CTC) leading to the yellow colors. [7][8][9][10][11][12][13][14] This attempt was effective in part but not perfect over the * Author to whom correspondence should be addressed. entire visible light range.…”

Synthesis and characterization of hybrid films of polyimide and silica hollow spheres

“…In samples containing a low concentration of a-SHS, the normal transparency was attributed to small-sized SHS (~200 nm from TEM measurement) that were smaller than the wavelength of visible light (400~700 nm) and thus minimized the loss of light scattering. 42 However, the hybrid films gradually lost their transmittance with increasing contents of a-SHS because larger particles generated by the aggregation of the SHS nanoparticles brought about light scattering, reducing optical transmittance of the hybrid films. Figure 9 represents the FE-SEM micrographs of the crosssections of the hybrid films at both low and high magnifications.…”

“…The thermal stability of organic polymers can also be enhanced by introducing inorganic materials, such as silica, because these materials have a good thermal stability. [34][35][36][37][38][39][40][41][42][43] Dynamic mechanical analysis (DMA) was used to study the influence of the SHS phase in the molecular relaxation processes of the PMDA-ODA PI. As shown in Figure 11, the neat PMDA-ODA PI film and all the PMDA-ODA PI hybrid films exhibited two transition peaks in the tan δ curves, one small peak around 200 o C and another strong peaks in the range of 250~500 o C. In Figure 11, the DMA data for the PMDA-ODA PI/a-SHS hybrids containing 1 wt% and 3 wt% are not shown since no significant difference has been observed from that of the neat PMDA-ODA PI.…”

A Pronounced Dispersion Effect of Crystalline Silicon Nanoparticles on the Performance and Stability of Polymer:Fullerene Solar Cells

“…33,34 In this work, as an alternative idea for the stability improvement in the BHJ polymer solar cells, we tried to add inorganic nanoparticles to the P3HT:PC 61 BM films because inorganic materials are typically more stable than organic materials. 35,36 To not degrade the semiconducting (electrical) property of the BHJ films as well as the charge separation balance between electron donor (P3HT) and electron acceptor (PC 61 BM), we employed crystalline silicon nanoparticles (SiNP) because they are a well-known inorganic semiconductor with a similar valence band energy to the highest unoccupied molecular orbital (HOMO) energy of P3HT so that the hole charge carrier transport at least cannot be severely degraded. 37,38 In particular, we attached alkyl groups to the surface of SiNP via an esterification reaction in order to bestow better solubility (dispersion) in chlorobenzene solvent, which can lead to better dispersion quality of the inorganic nanoparticles in the BHJ films.…”