Unperturbed dimensions of polymers revisited through the blob theory: the viscometric expansion factor

Plotting log([η]/M1/2) versus log(N/Nc) where [η] is the intrinsic viscosity of the macromolecular chain of molecular mass equal to M and N/Nc is the number of blobs of which this chain consists (N: the number of statistical segment of the chain and Nc : the number of statistical segment of one blob), we obtain the unperturbed dimensions parameter of the blob, Kθb. This graphical representation in this article is based on a modified, original equation of Han [6] based on the blob theory. The obtained value of Kθb for a given polymer, dissolved in a good solvent, is lower than the unperturbed dimensions parameter, Kθ, obtained for the same polymer in the Flory’s theta conditions. Having Kθb < Kθ we obtain for the viscometric expansion factors of a polymer, based on Kθb or Kθ, αηb > αη. With the obtained values of αηb we find αηb3/αs2αH ≈ 1, as predicted by Weill and des Cloizeauz [1], where using αη we obtain αη3/αs2αH ≈ 0.85 (αs and αH are the static and dynamical expansions factors).

Effect of Dipolar Side Groups on Conformational Properties of Heteroatom Polymers

The unperturbed dimensions of symmetric polymers are investigated by an improved conformational statistic method considering effect of side groups. Following the deduced formulas, the characteristic ratios of mean-square radius of gyration for poly(dimethylsilmethylene) (PDMSM), poly(vinylidene fluoride)(PVDF), polyphosphate(PP), polyoxymethylene(POM) and poyisobutylene (PIB) are calculated 0.69, 0.84, 1.23, 0.85 and 1.18, respectively. The ratios of mean-square dipole moment are 0.35, 0.48, 0.59 and 0.79 for PP, PDMSM, POM and PVDF long chains, respectively. From comparing the ratios of five polymers, it is found that the consideration of side groups for short chains is exceedingly important in calculation of characteristic quantity, especially for the inorganic polymers with heteroatom. PVDF are excellent in flexibility and electric dipole properties. The temperature characters of PIB are concerned closely with its conformational energy.

Correlation between solution and gel properties of copolymers of acrylamide and diallyldimethylammonium chloride

Several copolymers formed by acrylamide and diallyldimethyl ammonium chloride containing different fractions of charged diallyl residues, x, were synthesized. Solution properties of linear samples of these copolymers were studied by size exclusion chromatography coupled to differential refractive index and light scattering detectors, which allowed the determination of molecular weight averages, molecular dimensions, scaling law coefficients, and unperturbed dimensions. The results were compared with those of the corresponding homopolymers i.e., polyacrylamide and poly(diallyldimethylammonium chloride). On the other hand, crosslinked samples of the copolymers were prepared and their swelling in water was studied. The correlation between the solution properties of the linear samples and the swelling behaviour of their crosslinked counterparts can be illustrated through the relationship between the characteristic ratio of the unperturbed dimensions and the equilibrium degree of swelling since both magnitudes exhibit a similar dependence on x. Moreover, this dependence is not linear and it passes through a maximum at ca. x ≈ 0.5.