AbstractIR, NMR, ORD, and UV measurements were carried out on the poly‐(+)‐2‐methylbutyl acrylates obtained by the radical (R‐PMBA) and anionic (A‐PMBA) polymerization processes and on the (+)‐2‐methylbutyl isobutyrate (model compound).There are not any differences in IR and NMR spectra of R‐ and A‐PMBA. The values of molar rotation decrease in the order of R‐PMBA, A‐PMBA, and the model compound, while the values of the extinction coefficient decrease in the order of A‐PMBA, R‐PMBA, and the model compound.Temperature coefficients of the molar rotation of PMBA polymers and the model compound are of the order of 10−3 between 30 and 60°C, but the temperature dependence of the extinction coefficients is very small.The observed temperature dependence of optical activity arise mainly from the conformational variations of side chains though very local conformational contributions of the main chain would exist.The absorption peak of the model compound shifts to the shorter wave length region when the polarity of the solvent used is larger.