In formamide as solvent, poly (y-benzyl-L-glutamate) is found by light scattering experiments to have a radius of

Question:

In formamide as solvent, poly (y-benzyl-L-glutamate) is found by light scattering experiments to have a radius of gyration proportional to M; in contrast, polystyrene in butanone has Rg proportional to M1/2. Present arguments to show that the first polymer is a rigid rod whereas the second is a random coil.