Hybrid - block copolymer nanocomposites. characterization of nanostructure by small-angle X-ray scattering (SAXS)*

Abstract

The nanoscopic order of a series of block copolymer-inorganic nanocomposites was characterized using small-angle X-ray scattering (SAXS). The nanostructures were obtained via a diblock copolymer directed sol-gel synthesis. The copolymer consists of blocks of poly(isoprene) -PI- and blocks of poly(ethylene oxide) -PEO. The inorganic material consists of a crosslinked sol of\linebreak 3-glycidoxypropyltrimethoxysilane and aluminum-tri-sec-butoxide in a 4:1 mole ratio, to generate an aluminosilicate ceramic. The PEO block is swollen by the ceramic precursor and acts as a nanoreactor for their sol-gel synthesis. The resulting nanostructured hybrid has PI as the majority phase. Two series of nanocomposites, designated PI-b-PEO-D and PI-b-PEO-E, were studied; these correspond to 15 wt% PEO and 13 wt% PEO, respectively. The results showed that the nanoscale order characteristic of block copolymers (lamellar, spherical, and cubic) is not only achieved in these hybrid nanocomposites, but the molecular assembly offers the possibility of being utilized as a template for highly ordered inorganic nanostructures. The amount of inorganic nanofiller and the molecular weight of the blocks define the type of morphology assumed by the nanostructure.