Carbon nanotubes have been shown to efficiently quench luminescence from conjugated polymers when incorporated in a composite. However, shown here is an up to 100-fold increase in the visible photoluminescence signal from fluorescent chromophores in nylon 10,10 by incorporating multi-walled carbon nanotubes (MWCNTs). Using 325- and 488-nm excitation the optical absorption by MWCNTs embedded within the polymer matrix is demonstrated, followed by efficient excitation-energy transfer to emissive chromophores intrinsic to the polymer but only when the MWCNTs are acid functionalized. Furthermore, the MWCNTs are shown to significantly retard photobleaching of fluorescent centers in the nylon composites. These remarkable properties greatly advance the prospects of utilizing MWCNTs in organic solar cells and electroluminecent devices to improve performance.

An analytical study is presented for the transient electrophoretic response of a circular cylindrical particle to the step application of an electric field. The electric double layer adjacent to the particle surface is thin but finite compared with the radius of the particle. The time-evolving electroosmotic velocity at the outer boundary of the double layer is utilized as a slip condition so that the transient momentum conservation equation for the bulk fluid flow is solved. Explicit formulas for the unsteady electrophoretic velocity of the particle are obtained for both axially and transversely applied electric fields, and can be linearly superimposed for an arbitrarily-oriented applied field. If the cylindrical particle is neutrally buoyant in the suspending fluid, the transient electrophoretic velocity is independent of the orientation of the particle relative to the applied electric field and will be in the direction of the applied field. If the particle is different in density from the fluid, then the direction of electrophoresis will not coincide with that of the applied field until the steady state is attained. The growth of the electrophoretic mobility with the elapsed time for a cylindrical particle is substantially slower than for a spherical particle.

The transient response of ionic solutions in the porous medium constructed by a homogeneous assemblage of parallel charged circular cylinders to the step application of an electric field and a pressure gradient in the axial direction is analyzed through the use of a unit cell model. By solving the Poisson–Boltzmann equation and modified Navier–Stokes equation applicable to the system, the electric potential distribution and time-evolving velocity profile in the fluid phase are determined for arbitrary electric double layer thickness and zeta potential associated with the dielectric cylinders. Results for the flow rate, electroosmotic velocity, and effective electric conductivity of the fluid are obtained as functions of the elapsed time and the porosity of the fibrous medium. The effects of the relevant parameters on the transient starting electrokinetic flow in the fiber array are significant and interesting. For a fibrous medium with smaller porosity, a much shorter elapsed time is needed for the fluid velocity and electric current density to be within a certain percentage of their steady-state values.