Carboxymethylcellulose (NaCMC) is the most widely used cellulose derivative; it forms an anionic, water-soluble, polyelectrolyte with vast applications in the food, pharmaceutical, personal care/cosmetic, paper and other industries. Surprisingly little is known about its conformation in aqueous solution and in mixed solvents, for which the polymer conformation is expected to change qualitatively, eventually reaching a pearl-necklace conformation before fully collapsing. SANS will uniquely allow us to quantify the effect of degree of substitution, (1) non-solvent, (2) salt and (3) temperature on the conformation and spatial correlations and scaling laws of this model PE in solution, thus allowing a greater understanding and possible optimisation of manufacturing processes.