Peculiarities in the physico-chemical behaviour of non-statistically substituted carboxymethylcelluloses

A characteristic feature of sodium carboxymethylcellulose (NaCMC) samples s ynthesized via an NaOH-induced phase separation process is the almost compl ete substitution in O-6 position and the significantly higher content of tr icarboxymethylated units, leading to a small increase of the acidity consta nt. SEC/MALLS/DRI measurements of the NaCMC samples show a trimodal curve, including a high molar-mass peak which can be attributed to aggregates or a ssociates of different geometries and high density. With regard to the poly electrolyte complex formation process, these more compact aggregate structu res cause the formation of more compact polyelectrolyte complexes with sign ificantly smaller dimensions and higher particle density. Consequently, ord ered polyelectrolyte complex structures appear. Furthermore, this type of u nconventionally substituted NaCMC sample can be put to good use for stabili zing colloidal dispersions, e.g. colloidal BaSO4. Due to the good adsorptio n of the NaCMC sample onto the colloidal particle surface, multiple polyani on-polycation coating layer-by-layer becomes possible. (C) 2001 Published b y Elsevier Science B.V. All rights reserved.