Mobility restrictions in solid-state photopolymerization give extremely poor polymerization kinetics, but octadecyl acrylate can be rapidly photopolymerized in the solid state. The XRD, real-time Fourier transform IR and DSC analyses prove that the hexagonal packing of monomer molecules is favorable for UV-initiated solid-state polymerization, and crystalline long alkyl chains of monomers were preserved as the crystalline long alkyl side-chains of polymers. More importantly, octadecyl acrylate provides a chance to investigate the shrinkage and oxygen inhibition of UV-induced solid-state polymerization. This novel radical-mediated solid-state photopolymerization is insensitive to oxygen and lowers the volume shrinkage (1.48%). (c) 2013 Society of Chemical Industry