1 Structural Analysis of Polymer-Inorganic Nanocomposites by Synchrotron X-ray Scattering Pranav Nawani † , Hongwen Zhou † , Benjamin Chu, Christian Burger* and Benjamin S. Hsiao* Chemistry Department, Stony Brook University, Stony Brook, New York 11794-3400. † Equal contributors. * Correspondent authors. Tel: 1-631-331-4462 (Burger); 1-631-632-7793 (Hsiao) Fax: 1-631-632-6518 E-mail: cburger@sunysb.edu (Burger), bhsiao@notes.cc.sunysb.edu (Hsiao) ABSTRACT In this study, synchrotron small-angle X-ray scattering (SAXS) was used to characterize the structure of polymer-inorganic nanocomposite materials containing platelet-shaped nanofillers. New analytical schemes were developed and applied to scattering from two different systems, a synthetic organoclay in which the inorganic layered silicates are randomly distributed in an organic matrix, and naturally occurring bone collagen fibrils in which the mineral platelet crystals (calcium hydroxy apatite) are deposited at specific sites of a highly-ordered fibrous organic matrix. The analytical results provide quantitative structural information on the size, shape, preferred orientation, and the 3D spatial relationship between the organic and inorganic components that are complimentary to and usually go beyond the limits of transmission electron microscopy (TEM). Keywords: polymer nanocomposite, preferred orientation, organoclay, collagen, bone.