Association of Amino-Terminated Polystyrenes. 2. Dynamic Light Scattering of Associating Linear Chains

Abstract

Dynamic light scattering was used to study the associating coupling process of aminoterminated polystyrene chains with monofunctional and bifunctional dinitrophenol reagents. The tertiary amino end group and the end group which results from association with monofunctional dinitrophenol were found to have no effect on the solution behavior in good solvents. The interaction with the coupling reagent caused a decrease in the mutual diffusion coefficients Dc with increasing polymer concentration. Translational diffusion coefficients Dz°(c) of the associating polymers at each concentration c with a corresponding molecular weight Mw(c) were determined from Dc and its concentration dependence which is expressed by the kD parameter. The molecular weight dependence of the kD parameter was obtained from experimental values of linear polystyrenes in toluene. On the time scale of these experiments, the associates were found to show a diffusion behavior that corresponds to covalently linked chains. Apparently the lifetime of a complex is longer than the measurement time in typical experiments.

Association of Amino-Terminated Polystyrenes. 3. Trifunctional Star Polymers

“…Previously, it was shown for monofunctional and telechelic amino-terminated PS that the presence of this end group does not cause a change in the solution properties when a good solvent is used. , Figure shows A 2 of the amino-terminated three-arm stars and literature data for untagged three-arm stars. As expected, there is no significant change detectable between amino-terminated and common PS stars.…”

“…Probable reasons for g A2 > 1 were discussed previously. 14 The translational diffusion coefficients of linear PS were found to follow a power law over a wide range of molecular weights 5,12,17 M w > 30 × 10 3 [g/mol]. This allowed us to calculate the hydrodynamic shrinking factors g h for all three star polymers in Table 1.…”

“…A 2 ( c ) is the second virial coefficient of an associate with the corresponding molecular weight M w ( c ), which implies that A 2 of an associate with M w ( c ) is the same as A 2 of a covalently linked polymer with exactly the same molecular weight and architecture. Adequacy of this assumption was shown in several cases. ,,, Inserting these expressions in eq 2 the molecular weight M w ( c ) at concentration c can then be extracted from the scattered intensity at each concentration c if the exponent a A 2 and the g factor are known. A closed expression could be derived if g = 0.33 and a A 2 = 0.5, but for all other pairs a numerical procedure has to be applied to find M w ( c ).…”

“…Adequacy of this assumption was shown in several cases. 2,5,19,20 Inserting these expressions in eq 2 the molecular weight M w (c) at concentration c can then be extracted from the scattered intensity at each concentration c if the exponent a A2 and the g factor are known. A closed expression could be derived if g ) 0.33 and a A2 ) 0.5, but for all other pairs a numerical procedure has to be applied to find M w (c).…”

Supramolecular Association of Acid-Terminated Poly(dimethylsiloxane)s. 2. Molecular Weight Distributions

“…Since Figure shows that even at 1.4 g/L acid groups are still mainly dimerized, the low viscosity can only be explained if intramolecular association is taking place and demonstrated in the case of telechelic polystyrene chains coupled by acid−base interactions …”