Vinyl polyperoxides, alternating copolymers of vinyl monomers and molecular oxygen, are highly viscous amorphous materials because of the flexible peroxy (-O-O-) bonds in the main chain. In this study, crystalline polyperoxides have been synthesized by oxidative radical polymerization of styrenic monomers having fatty acid moieties attached to the phenyl ring using molecular oxygen at 100 psi pressure. Determination of active oxygen contents in polyperoxides, C-13 NMR spectroscopy, and electron impact mass spectroscopy (EI-MS) confirmed alternating placement of -O-O- bonds after every styrenic monomer unit in the copolymer main chain. Thermal stability was studied by thermogravimetric analysis (TGA). Exothermic degradation of these polyperoxides was observed by differential scanning calorimetry (DSC), and degradation products have been identified from EI-MS study. DSC and powder X-ray diffraction (PXRD) studies revealed crystallinity in the polyperoxides with fatty acids having 12 carbon atoms or longer. This crystalline behavior was further supported by polarized optical microscopy (POM), where a birefringence texture which is characteristic of semicrystalline polymer was formed for polyperoxides with C >= 12 of the side-chain alkyl carbons. Transmission electron microscopy (TEM) was used to define the thickness and crystal structure of the polymers. Theoretical studies have been performed using density functional theory (DFT) to support the experimental interlamellar distance from X-ray diffraction studies.