An Amphiphilic Poly(phenylene ethynylene) as the Structure-Directing Agent for Periodic Nanoscale Silica Composite Materials

Abstract

We have synthesized optically active nanostructured composite materials by using an amphiphilic semiconducting polymer, a poly(phenylene ethynylene) (PPE), and a conventional ammonium surfactant as the structure-directing agents. The PPE consists of phenylene units para-substituted with an octyloxy chain and a charged trimethylammoniumethoxy group, resulting in a surfactant-like structure that can assemble into cylindrical micelles. The resulting silica/organic composite material has a hexagonal honeycomb structure with a repeat distance of 45.3 A, as confirmed by low-angle X-ray diffraction and transmission electron microscopy. Scanning electron microscopy indicates that the larger scale particle size is on the order of micrometers. The incorporation of the polymer into the composite was confirmed by elemental analysis, photoluminescence spectroscopy, and fluorescence microscopy. The polymer retains its photophysical properties in the composite, showing luminescence similar to polymers in the solution phase. The polymer displays a high degree of luminescence polarization anisotropy, indicating that the polymer chains are straight and isolated from each other in the composite.