A Comparative Study Using Small-Angle X-ray Scattering and Solid-State NMR of Microdomain Structures in Poly(styrene−butadiene−styrene) Triblock Copolymers

Abstract

The complementary techniques of solid-state NMR and small-angle X-ray scattering (SAXS) have been used to determine the microdomain structures of a series of commercial poly(styrene-b-butadiene-b-styrene) triblock copolymers with different molecular weights. The relative locations of multiple scattering peaks, indirect transform, and Porod analysis have been used to determine the morphology and the sizes of various domains as well as the interfacial thickness between them. Solid-state NMR of 1H spin diffusion measurements was also used to estimate the microdomain structure parameters by simulating the spin diffusion processes with a model that considers the effects of 1H spin−lattice relaxation. The interfacial thickness, 2 nm for all five materials, and the interdomain distances, ranging from 30 to 42 nm, from NMR agree well with results from SAXS techniques. There are some discrepancies for some of samples regarding the domain sizes of dispersed polystyrene phases obtained from the above two techniques. These discrepancies may be mainly caused by the limited quality of the fitting procedure using indirect transform methods.

2H NMR spin relaxation study of the soft segment motion in alternating ethylene–propylene copolymers

“…8 Our results concerning the relaxation behavior of the soft segment for the block copolymers were in good agreement with their results. Similar observations have been also reported in a number of systems, such as poly(styrene-b-butadiene-b-styrene), 9 segmented polyesters 15,16 and polymethacrylate tethered on silica particles. 17,18 Figure 2(a) shows the temperature dependence of the relaxation time for component A.…”

“…They also measured the thickness of poly(styrene-b-butadieneb-styrene) triblock copolymers under the same assumption using the same technique. 9 The interfacial thickness obtained in these investigations was in good agreement with those obtained by SAXS. Furthermore, Lin and Blum reported that the relaxation time of polymethacrylate tethered on silica particles was the same as that of bulk polymethacrylate.…”

Restricted Molecular Dynamics of Polymer Chains by Means of NMR Field Cycling Relaxometry

“…For the system under study, the spin diffusion coefficients were reported as 0.05 nm 2 · ms −1 and 0.80 nm 2 · ms −1 for PB and PS components, respectively 39. An estimate of the rms displacement of magnetization,〈 x 2 〉 1/2 , following Einstein's relation 〈 x 2 〉 = 2 Dt in one dimension (taking account of the lamellar structure of the system), leads to rms values of 2 nm and 9 nm for PB and PS, respectively, for an exemplary time scale of 50 ms which represents a T 1 value at intermediate frequencies.…”

Nanovoid characterization of nominally pure aluminium using synchrotron small angle X-ray Scattering (SAXS) methods

“…When the constant background term C 0 is removed [40], the slope obtained at high q can be used to obtain a measure of the specific surface area (S/V), assuming an ideal, sharp interface between the void and the metal matrix. However, when a diffuse interface is encountered, the meaning of S/V is not well defined and obtaining an estimate of interfacial thickness is then more meaningful.…”