A dielectric study of a carboxymethylcellulose in aqueous solution

Abstract

The dielectric properties of proteins in polar solvents have been extensively studied, and recently some linear polyelectrolytes-nucleic acids, nucleohistone, and hyaluronic acid-in polar solvents have been investigated at this l a b o r a t~r y .~-~ Most proteins studied have been highly polar and belong to the relatively small group of substances which give dielectric increments in solution. This is also the case for the linear macromolecules mentioned above, and these are still more polar so that they may be investigated in very dilute solutions. For these substances with axial ratios exceeding 10: 1, it was possible to calculate molecular weights from the relaxation times obtained dielectrically. --6 A number of polyelectrolytes have similar pliysicochernical properties aiid are better defined chemically and might thus serve as "model substances" for dielectric investigation. Though it may not be looked upon as a dipolar ion, the sodium salt of a carboxymethylcellulose (CMC) was chosen for this study. EXPERIMENTALA pharmaceutical sample of CMC (kindly supplied by AB Hassle, HEssleholm, Sweden) was purified by centrifuging a 1% solution at 20,OOOg for 1 hour to remove a slight amount of insoluble material, followed by dialysis against distilled water. The "salt-free" solution was then freezedried. The white porous material obtained had a moisture content of 7.4% (the specimen was dried at 95°C. and 0.1 mm. Hg over phosphorus pentoxide for 20 hours). The sodium content of the "moisture-free" substance was 5.78% (determined with flame photometer), corresponding to a ratio of carboxymethylglucose to glucose in CMC close to 1 : 1 if the sodium found is assumed to correspond to the carboxyl groups only, which seems reasonable when considering the pretreatment of the specimen.The viscosity of CMC (specimen IV) in aqueous solutions below 0.1% (20 "C. in an Ostwald viscometer) showed similar dependence upon concentration as for other polyelectrolytes, vs,/c varying between 35 (0.1%) and 50 (0.02%) and falling again at still lower concentrations (c = concentration in grams per 100 ml.).The solutions investigated were prepared by dissolving weighed amounts of substance in redistilled water, using a shaking machine. Complete dis-229

Influence of Various Physicochemical Factors on Hemagglutination

“…This theory appears at first sight attractive and has enjoyed some degree of acceptance [29], Two things, however, are wrong with it: (1) Some of these polymers, for example dextran [4][5][6][7], do not cause a decrease, but an increase in the f-potentials of cells as do also the strongly negatively charged nucleic acids [19]. (2) Albumin, although it increases the dielectric constant of water somewhat, is unlikely to cause increases to the extent noted by Pollack et al [42], see Oncley [31]; while dextran, being virtually apolar cannot and does not have any not able effect on the dielectric constant of wa ter at all [2,24].…”

Relaxational behavior of birefringence of aqueous carboxymethylcellulose under an alternating electric field at frequencies ranging from 0.1 Hz to 100 kHz

“…Allg6n and Roswall [11,12] and later Allen et al [13] observed a dielectric relaxation of aqueous CMC at 0.3 to 20 MHz. Their results suggest that our constant part of An at 100 kHz may relax with further increase of frequency above 100 kHz, which is denoted relaxation A in the following.…”

“…According to the dielectric studies by Allg~n and Roswall [11] and Allen et al [13], the relaxational frequency fA is rather insensitive to molecular weight and increases with increasing Cp and Cs. Our results indicate that the relaxation strength 6(An)A levels off with increasing Cp.…”

“…In the case of NaCMC, AIlg~n and Roswall [11] found the HF relaxation and Oga et al [14] the LF one. Relaxation B in the dynamic electric birefringence should correspond to the LF dielectric relaxation and relaxation A to the HF one.…”

Electric Properties of Carboxymethyl Cellulose

“…Dielectric spectroscopy of aqueous solutions of NaCMC shows two dispersions: highfrequency [47] and low-frequency [48]; the presence of two dispersions is typical for polyelectrolytes. The high-frequency dispersion is independent on the contour length but the low-frequency is strongly dependent on it; on this base the two frequency regions are attributed to counterions moving along chain's parts or along the hole polyelectrolyte chain, respectively [49,50].…”