E. V. Korneeva

Flow birefringence of pullulan molecules in solutions

Abstract Flow birefringence (FB) of polymaltotriose (pullulan) in water and in dimethylsulfoxide (DMSO) has been studied. Pullulan has a high refractive index increment ( Δn Δc ) in water but in DMSO it is low. Accordingly, in water the FB of molecules is mainly determined by the macroform effect and in DMSO by the intrinsic anisotropy of polarizabilities of the polysaccharide chain. The analysis of the dependencies of reduced FB values [n] [η] on molecular weight and on Δn Δc makes it possible to determine quantitatively the value of intrinsic segmental anisotropy of pullulan molecules: (α1 − α2) = +33 × 10−25cm3. On the basis of this value the optical anisotropy of the glucopyranose ring was determined.

Hydrodynamic and Molecular Characteristics of Poly[1-(trimethylgermyl)propyne]

Samples and fractions of a membrane-forming polymer poly[1-(-trimethylgermyl)propyne], with the molecular weight within 4 < M × 10-4 < 170 were studied in cyclohexane by methods of molecular hydrodynamics (centrifugal sedimentation, translational isothermal diffusion, and viscometry). The molecular weight dependences of the hydrodynamic characteristics were determined and analyzed. These dependences were used to estimate the equilibrium rigidities of the poly[1-(trimethylgermyl)propyne] chains. The size of the macromolecules was studied as influenced by the bulk effects. The results obtained are compared with published data for poly[1-(trimethylsilyl)propyne].