Critical fluctuations and relaxation phenomena in the isotopic blend polystyrene/deuteropolystyrene investigated by small angle neutron scattering

Abstract

Articles you may be interested inSmall-angle neutron scattering studies of polybutadiene/polystyrene blends as a function of pressure and microstructure: Comparison of experiment and theory Effect of the Onsager coefficient and internal relaxation modes on spinodal decomposition in the high molecular isotopic blend polystyrene/deuteropolystyrene studied with small angle neutron scattering Early state of spinodal decomposition studied with small angle neutron scattering in the blend deuteropolystyrene and polyvinylmethylether: A comparison with the Cahn-Hilliard-Cook theory J. Chem. Phys. 97, 8775 (1992); 10.1063/1.463347 Shear stabilization of critical fluctuations in bulk polymer blends studied by small angle neutron scattering J. Chem. Phys. 93, 795 (1990); 10.1063/1.459533 Investigation of the phase diagram and critical fluctuations of the system polyvenylmethylether and d polystyrene with neutron small angle scatteringFor the isotopic blend of polystyrene (PS)/deutero PS (M w = 10 6 dalton), the Flory-Huggins interaction parameter X(rp,n was determined by means of the structure factor SeQ) measured by small angle neutron scattering (SANS). From X(rp,n, the miscibility gap and the corresponding spinodal line was evaluated with a critical temperature of 130 ·C. Decomposition in the miscibility gap is extremely slow due to the critical slowing down and due to a glass transition 30 K below Te. Furthermore, the transition ofthe homogeneous blend between two temperatures was investigated by SANS. The interdiffusion constant of the two isotopic species was determined from these experiments. Our results approach the Cahn-Hilliard-Cook theory only in the limit of small wavenumbers of the fluctuations. Three weeks after annealing the sample, demixing was observed in the predicted two-phase region.J. Chem. Phys. 93 (11).

Conformation of Cyclics and Linear Chain Polymers in Bulk by SANS

“…Similar downturn composition dependencies of the interaction parameter have been observed for other isotopic mixtures. [47][48][49] The results reported here are in good agreement with values from Beaucage et al for isotopic symmetric equimolar mixtures of linear H/D PDMS. In that work, interaction parameters were evaluated from the SANS profiles as a function of molecular weight and temperature, and this made it possible to establish a general relationship between , M w , and T:…”

Concentration and chain-length dependence of thermodynamic interactions in polyethylene isotope blends

“…The ylene) 6 and in blends of certain polyolefins. 9,10 binodal in Figure 5 has a shape almost exactly Precisely the same arguments, with only the sign the same as that for the constant x FH case, the of g being negative instead of positive, apply to ratio between the two varying by less than 2% (glassy) hPS/dPS 5,7 ; here the binodal would be over the range 0.05°f 1°0 .95. This insensitivity shifted downward and x NS (0.5) ú x(0.5).…”

“…Downward curvature of x NS was not seen; that behavior seems unique to hPS/dPS blends. 7,5 Indeed, upward curvature of x NS seems to be the rule, rather than the exception. Alamo et al 10 considered blends of polydisperse low-density polyethylene (having both short and long chain branching) with polydisperse dPE.…”

“…rium for hydrogen, [5][6][7] which is required for SANS contrast. While isotope blends would be thought to approximate most closely the constant x FH emComparison of eq.…”

Nanostructure formation in polymer thin films influenced by humidity

“…The demixing of immiscible polymer blend mixtures has been studied intensively for many years. 2,3 Polymer blend films are of increasing interest in the field of surface technology because they can be used to change or tailor the properties of surfaces for special application. 4 used as antireflection coatings.…”