13C NMR study of radical copolymers of (-)-menthyl methacrylate with trans-4-methacryloyloxyazobenzene

The 50.3 MHz 13C NMR of free radical copolymers of (-)-menthyl methacrylate with trans-4-methacryloyloxyazobenzene having different composition was investigated in CDCl3 solution at room temperature. The smooth variation of the chemical shifts of aromatic carbons with chemical composition points to a random distribution of the monomeric units along the polymer chain. Analysis of the carbonyl signal allows one to determine the main chain stereochemistry of copolymers in which one monomer predominates. Apart from the macromolecular nature, no appreciable effect on local mobility is observed arising from different neighboring units and stereoregularity.