Rt. Myers et al., Use of ultra-small-angle X-ray scattering to measure grain size of lamellar styrene-butadiene block copolymers, MACROMOLEC, 32(8), 1999, pp. 2706-2711
Simultaneous determination of the lamellar morphological length scale and t
he grain size of several low molecular weight heterogeneous styrene-butadie
ne block copolymers was accomplished through the use of ultra-small-angle X
-ray scattering measurements. NIST's X23A3 Ultra SAXS beamline of the Natio
nal Synchotron Light Source in the Brookhaven National Laboratory provided
a scattering vector, q, from 0.0004 to 0.1 A(-1). Many of the block copolym
er specimens display a clearly resolvable peak in the Ultra SAXS region, an
d grain size was determined using the spherical form factor. Determination
of Pored's law constant and the value of the scattering invariant provided
a preliminary verification of the proposed scattering mechanism by solving
for the contrast factor and the volume fraction of the grain boundaries in
these specimens. Grain size in a given polymer was a function of annealing
temperature and time. For the case of a block copolymer swollen with varyin
g amounts of cumene, both the lamellar repeat distance, d, and the grain si
ze, D, increased with the cube root of the volume fraction of solvent over
the concentration range examined.