SynopsisThe spin-labeled and spin-probed alternating copolymers of poly(phenylviny1 alkyl ethers) with various alkyl groups (Me, Et, secBu) in the ether moiety were investigated by electron ,spin resonance (ESR). Measurements were taken in different solvents over a wide range of concentration. Studies reveal that the molecular motion of spin-labels and spin-probes depends on the bulkiness of the alkyl group at the solvent concentration in which the effect of segmental rotation is dominant. The implication of the type of chemical bonding on the nitroxide motion is discussed.