Abstract: Aset of AM-AAcopolymer samples with the same comonomer content and differ ent average molecular weight have been chracterized by ¹³CNMR and light scattering methods in this paper.The chemical composition(comonomer AA,mole content 16.9±1.1%)of these samples is uniform, the sequence of AA in the macromolecular chain is of alone and random distribution and the light scattering theory from polyelectrolyte in added-salt solutions is suitable for the AM-AA copolymers-0.12 mol/L NaCl water systems. The actual values of M_w,the second Virial coefficient A₂and the mean square radius of gyration〈R₂〉_zfor the studied samples have been obtained,The relationships between the molecular parameters are as follows:A₂=0.0619M_w^-0.21,〈R²〉_z^1/2=0.0210M_w^0.54.

Key words: Water soluble polymer, Acrylamide copolymer, ¹³CNMR, Light scattering