The presence of a main-chain correlation distance (d(II)) in the poly(di-n-alkyl itaconate)s was confirmed with small-angle X-ray scattering/wide-angle X-ray scattering measurements taken over the temperature range of 293-478 K. Data for a series of alkyl acrylate polymers were also obtained for comparison. The intensity of the itaconate d(II) peak was significant and indicated a greater level of nanophase formation than in analogous systems. In the lower members of the series, nanophase formation appeared to be further enhanced in the temperature range above the glass-transition temperature (T-g). This was ascribed to the rapidly increasing main-chain mobility in this region. Macroscopically phase-separated itaconate blends displayed the individual d(II) nanospacings of each homopolymer component. Copolymers, on the other hand, showed more interesting behavior. Poly(methyl-co-di-n-butyl itaconate) followed an average behavior in which the d(II) spacing and T-g changed progressively with the comonomer content. In contrast, the side-chain pairing in poly(methyl-co-di-n-octyl itaconate) generated d(II) spacings characteristic of separate methyl and octyl nanodomains. The observation of the dioctyl nanodomains, along with the dioctyl side-chain lower T-g relaxation event, confirmed the concept of independent side-chain-domain relaxation in these polymers. The temperature behavior of the poly(methyl-co-di-n-octyl itaconate) small-angle X-ray scattering profiles and scattering correlation lengths indicated that the two nanodomains were not completely structurally independent. (C) 2004 Wiley Periodicals, Inc.