Long-range inhomogeneities in sulfonated polystyrene ionomers

Journal Article · Mon Jul 19 00:00:00 EDT 1993 · Macromolecules; (United States)

DOI:https://doi.org/10.1021/ma00067a042· OSTI ID:6325132

Li, Y; Peiffer, D G; Chu, B ^[1]

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1. State Univ. of New York at Stony Brook, Long Island, (United States). Dept. of Chemistry

Two Bonse-Hart ultra-small-angle X-ray scattering (USAXS) cameras were constructed and calibrated by using a polystyrene latex suspension and laser light scattering. The instruments were used to investigate the long-range inhomogeneities in a series of sulfonated polystyrene ionomers. The USAXS measurements were mainly centered in the region of q<0.1 nm[sup [minus]1] (where q is the magnitude of the scattering vector), which is beyond the reach of most conventional small-angle X-ray scattering (SAXS) instruments. All the scattering profiles of ionomers showed a small-angle upturn. The scattering behavior in this q region was not strongly dependent upon the counterions (except for the intensity change in amplitude), the compression-molding condition, temperature, and annealing. The small-angle upturn decreased with increasing ionic content for zinc sulfonated polystyrene ionomers, and increased with increasing ionic content for rubidium sulfonated polystyrene ionomers. By means of the Debye-Bueche model, an inhomogeneity length of around tens of nanometers was detected in the usual q range accessible by conventional SAXS (0.045-0.12 nm[sup [minus]1]). However, the USAXS curves based on the Debye-Bueche model showed a consistent downward curvature in the light-scattering q range. A Guinier plot also failed to show a simple characteristic length. Surprisingly, the upturn could better be described by a power law I[approximately]q[sup [minus][alpha]], with [alpha] ranging from 2.4 to 3.6 for the ionomers in this study, suggesting that, in the absence of long-range order, the structure could be very polydisperse and irregular. On the basis of USAXS results, the origin of the upturn is discussed. The majority of the upturn could result from chemical compositional inhomogeneities of the ionomers and the processing procedures used in forming the ionomer films for various physical measurements such as SAXS.

• DOE Contract Number: FG02-86ER45237; FG05-89ER75515
• OSTI ID: 6325132
• Journal Information: Macromolecules; (United States), Journal Name: Macromolecules; (United States) Vol. 26:15; ISSN MAMOBX; ISSN 0024-9297
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure &amp; Phase Studies
CALIBRATION
CAMERAS
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
MATERIALS
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
ORGANIC POLYMERS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
POLYMERS
POLYOLEFINS
POLYSTYRENE
POLYVINYLS
RADIATIONS
SCATTERING
SMALL ANGLE SCATTERING
SYNTHETIC MATERIALS
X RADIATION