High refractive index polyimide (PI)–chloride modified carbon black hybrid materials were prepared. The introduction of chloride modified CBs endowed the PI/CB nanocomposites with high refractive index, and the effect of the interaction between the five-membered imide rings and aromatic rings of CBs on the high refractive indices and transparency of the resulting PI/CB nanocomposites was discussed. The refractive indices of the prepared hybrid films at 633 nm were in the range of 1.711–1.833, which increased with the CB content from 0 to 10 wt%. According to the comparison of the theoretical and experimental values, the higher refractive index is mainly due to the effective enhancement of intra- and intermolecular charge transfer (CT) interactions between the five-membered imide rings and chlorine atoms attached directly to the CBs and the adjacent benzene rings of CBs. A theoretical equation based on the modified Lorentz–Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values. Transmission electron microscopy results indicated that the incorporation of CBs into polymer matrices on the nanoscale would assure the optical transparency.

In our previous report, poly(methyl vinyl ether-alt-maleic anhydride) grafted CB (GCB) with stable dispersion in water was successfully prepared. In the present study, waterborne polyurethane (WPU) nanocomposites including GCB and attapulgite (ATT) were prepared by liquid mixing method. Anionically charged GCB nanoparticles were heterocoagulated on the surface of cationically charged ATT nanorods at low pH value and improved the stabilization of ATT nanorods in water as a dispersing aid. The microstructure development in matrix that depended on various weight ratios of the nanoparticles ultimately influenced the electrical conductivity and mechanical properties of WPU nanocomposites. Composites containing equal concentrations of GCB and ATT showed reduced electrical conductivity, but significant increase in storage modulus. When the weight ratio of GCB to ATT was 5:1, both electrical conductivity and storage modulus of composite were improved simultaneously. The percolation threshold of composites containing a 5:1 (w/w) GCB/ATT ratio was lower than that of composites with GCB alone. The proposed mechanism for the effect of GCB and ATT on electrical or mechanical behaviors in composite was discussed in details. The clear evidence of microstructure development was also observed by transmission electron microscope.

Carbon black (CB)/polymer composites with high refractive index (RI) were fabricated from poly(vinyl alcohol) (PVA) and covalently functionalized nano-CB (PVA-es-CB) by simple esterification reaction. Transmission electron microscopy showed that uniform aggregates of PVA-es-CB nanoparticles with a size smaller than 100 nm formed in the nanocomposite films. Ellipsometric measurements indicated that the PVA-es-CB/PVA composite films had a RI in the range 1.520–1.598 linearly increased with the PVA-es-CB volume content. Theoretical equation based on Lorentz-Lorenz theory provided reasonably close estimation of the refractive indices to the experimentally observed values. The hybrid films also revealed relatively good surface planarity, thermal stability and optical transparency.

The composite films based on polyimide (PI) and chloride modified carbon black (CB-COCl) were prepared by conversion of biphenyltetracarboxylic dianhydride and 4,4′-oxydianiline in the presence of CB-COCl, followed by thermal imidization. The presence of chemical bonds between PI and CB-COCl, proved by FTIR spectra of the composites, has a considerable effect on the properties of PI films. Scanning electron microscopy (SEM) pictures of the PI/CB-COCl membranes showed changed morphology compared to reference membranes without CB-COCl. The thermal stability and structure of the composites were studied by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and X-ray diffraction (XRD), respectively. These hybrid films showed an increase in thermal decomposition temperature and a slightly enhanced glass transition temperature. On their mechanical properties, the modulus and ultimate strength of the hybrid films increased and elongation at break decreased with increased CB-COCl content. The surface free energy of polyimide films were determined by means of the contact angle measurements.

The composite films based on polyimide (PI) and chloride modified carbon black (CB-COCl) were prepared by conversion of biphenyltetracarboxylic dianhydride and 4,4′-oxydianiline in the presence of CB-COCl, followed by thermal imidization. The presence of chemical bonds between PI and CB-COCl, proved by FTIR spectra of the composites, has a considerable effect on the properties of PI films. Scanning electron microscopy (SEM) pictures of the PI/CB-COCl membranes showed changed morphology compared to reference membranes without CB-COCl. The thermal stability and structure of the composites were studied by differential scanning calorimetry (DSC), thermogravimetric analyses (TGA) and X-ray diffraction (XRD), respectively. These hybrid films showed an increase in thermal decomposition temperature and a slightly enhanced glass transition temperature. On their mechanical properties, the modulus and ultimate strength of the hybrid films increased and elongation at break decreased with increased CB-COCl content. The surface free energy of polyimide films were determined by means of the contact angle measurements.