C. J. Bloys van Treslong

Static light scattering from κ-carrageenan solutions

Abstract The polyelectrolyte behaviour of κ-carrageenan in NaCl and NaI solutions was investigated by static light scattering experiments. The solution properties of κ-carrageenan were found to be dependent upon the way the solutions were prepared. The dependence of the z-average radius of gyration and the second virial coefficient upon salt concentration exhibits normal polyelectrolyte behaviour in NaCl solutions for the range of ionic strengths considered. The persistence length as determined in the absence of long range interactions is found to be similar to values obtained for the majority of other polysaccharides. Within the same constraints of ionic strength a conformational change of the polymer chain is observed in NaI solutions without a noticeable change in molar mass. This observation is supported by measurements of optical rotation and the intrinsic viscosity.

Molecular characterisation of κ- and λ-carrageenan by gel permeation chromatography, light scattering, sedimentation analysis and osmometry

Abstract Gel permeation chromatography, in conjunction with a double detection system involving a low angle laser light scattering apparatus (LALLS) and a refractive index monitoring device (RI), has been used to obtain both the molecular weight and the molecular weight distribution of sodium salts of κ-carrageenan and λ-carrageenan in saline solutions. The results, M w and M n , are in excellent agreement with independent determinations of molar mass based on static light scattering experiments, sedimentation—diffusion analysis and osmometry. The relevance of the data is discussed with respect to current problems in carrageenan research.

Molar mass determination of the polysaccharide associated with coccoliths of emiliania huxleyi

Abstract Emiliania huxleyi is a marine alga which produces coccoliths, elaborate calcified structures consisting of CaCO 3 and a water-soluble acidic polysaccharide. The polysaccharide was subjected to light scattering measurements to determine the weight-average molar mass ( M w ) and osmometry to assess the number-average molar mass ( M n ). Values of M w of 88,600 ± 3200 g/mol and of M n of 49,100 ± 1500 g/mol were found. These experiments were performed with a polysaccharide mainly in the Na + form. Replacement of Na + by Ca 2+ did not significantly affect the weight-average molar mass or the second virial coefficient. The values of the refractive index increment of these salts were different [(d n /d c )Na + = 0.145 ± 0.004 ml/g; (d n /d c ) Ca 2+ = 0.090 ± 0.002 ml/g], indicating a possible conformational change in the molecule.

A new mark-Houwink equation for linear poly(ethylene imine)

Abstract A new Mark-Houwink equation for linear poly(ethylene imine) has been established in the molar mass range 2 × 10 3 M w 4 g mol −1 . The equation, resulting from viscosity measurements combined with weight-average molar mass determinations by light scattering in methanolic solution at 25°C, was found to be: [η] = (1.04 × 10 −2 ) M 0.95 w . The value of the exponent in the equation indicates the rigid structure of the polymer.

(Vinyl amine)-(vinyl alcohol) copolymers Synthesis, characterization and potentiometric behaviour

Abstract Some copolymers of vinyl amine with vinyl alcohol have been synthesized by hydrolysis of copolymers of tert.-butyl vinyl carbamate with vinyl acetate. From reaction kinetics and counterion distribution, it can be concluded that the copolymers are random. The potentiometric titration behaviour indicates that the very marked dependence of the dissociation constant on the charge fraction, even at high ionic strength, for this polyelectrolyte system may result from a very specific solvation process i.e. a strong dependence on the charge state of the interactions between polyion with counterions and solvent molecules.