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The aim of the present study was to obtain high-performance materials for heat and flame protective clothing. Therefore, hybrid membranes were prepared using Kevlar as support and aromatic polyimide nanofibers as a protective coating. The exceptional performances of the prepared membranes were highlighted by selected indicators: high thermal stability, fire resistance and improvement in air permeability without modifying drastically the water vapor transmission rate properties. Attenuated total reflectance Fourier transform infrared and 1H nuclear magnetic resonance spectroscopy were employed to confirm polyimide formation. The ability of polyimide to form fibers was investigated by rheological measurements and scanning electron microscopy, respectively. Thermal degradation was studied using thermogravimetric analysis and a microscale combustion calorimeter. The transport properties of the materials were examined by air permeability, water vapor transmission rate and water resistance. It was shown that transport properties of the modified Kevlar membranes could be controlled by varying the spinning time of polyimide solution. Moreover, by annealing the modified Kevlar weavings at 260℃, the structural integrity and transport properties were not affected, whereas a higher resistance to water was found.

Two new conjugated copolymers, PBDTTQ-1 and PBDTTQ-2, with a distinct linked pattern between benzodithiophene–thiadiazoloquinoxaline (BDTTQ) as acceptor and bithiophene as donor were synthesized and characterized. The difference in the linkage between donor and acceptor exerts great influence on the optoelectronic properties of the two polymers. The optical band gap decreases from 1.18 eV for PBDTTQ-1 to 1.03 eV for PBDTTQ-2, due to the lower LUMO energy level (−4.01 eV) of the latter. Moreover, density functional theory calculations demonstrate that the electron density is mainly confined on the acceptor unit in both HOMO and LUMO of PBDTTQ-1, while the electronic densities almost delocalize along the entire backbone of PBDTTQ-2, which facilitates the charge transport within the polymer chain. In contrast to PBDTTQ-1 missing any field-effect characteristics, PBDTTQ-2 exhibits ambipolar charge transporting behavior with mobilities of 1.2 × 10–3 cm2/(V s) for holes and 6.0 × 10–4 cm2/(V s) for electrons.

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