A nanostructured organometallic macromer trisilanolisobutyl-POSS (T-POSS) was used to prevent discoloration of poly(ethylene terephthalate) (PET) and to achieve molecular level stabilization during melt processing. The resultant material was investigated using thermal analysis and oscillatory rheology. The interaction between the PET and the nanostructured additive was investigated using X-ray photoelectron spectroscopy (XPS) and matrix-assisted