Analysis of small‐angle scattering of suspensions of organically modified montmorillonite: Implications to phase behavior of polymer nanocomposites

Abstract

A generalized model for scattering from a collection of independent (isolated) stacks of layers enabled predictions of and parameterized fits to small‐angle X‐ray scattering from layered silicate dispersions. From this fundamental development, example investigations that use small‐angle scattering to examine the structure of organically modified montmorillonite dispersions in toluene and toluene–acetone blends provided detailed information on the distribution of the stacks (relative concentrations, K and fraction of individual layers, χ) and characteristics of the intercalated crystallite (mean number of layers per stack, 〈N〉; layer repeat distance, D; and fractional stack disorder, δ). The analysis initially supported correlations with discotic phase behavior, which provides concise definitions for various morphologies (exfoliated, intercalated, and mixed). Finally, examination of the deviations between the scattering model and the experiment provided insights for improved experimental technique, more complete utilization of the scattering data, a sound basis for real‐time observations, insight into inconsistencies between scattering and microscopy, and minimization of incorrect or overinterpretation of data. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3214–3236, 2003

Morphology and properties of thermoplastic polyurethane composites incorporating hydrophobic layered silicates

“…In addition to the concentration of the scatterers, the orientation of the platelets has a large effect on the scattering intensity observed for a given scattering geometry. 22 The 3 wt % 15A melt-compounded composite scattered more strongly than the 7 wt % solvent-cast composite in transmission. This result suggests that melt processing and solvent processing give rise to different orientational stack distributions.…”

“…The smaller stack sizes in the melt-compounded composites were also detected qualitatively by the slightly broader full width at half-maximum values obtained from the WAXD d 001 diffraction peaks. 22 The smaller stack size achieved by melt compounding was a result of the higher shear stresses associated with this processing technique, which promoted the fracturing of layered silicate stacks. 23 The voids that can observed in the images of the solvent-cast samples are not associated with this processing method.…”

“…15A is produced with an excess of a quaternary ammonium surfactant, which is not ion-exchanged to the silicate surface. Vaia et al 22 postulated that the majority of the excess 15A surfactant is removed from the interlayer in a toluene solution. It is conceivable that the excess surfactant was replaced by PU.…”

“…This result suggests that melt processing and solvent processing give rise to different orientational stack distributions. 22 The peak at q Ϸ 0.05 Å Ϫ1 corresponded to scattering from the periodicity in the PU microdomain structure. Table IV.…”

Growth of Nano-Needles of Manganese(IV) Oxide by Atomic Layer Deposition

“…A bulk measurement is definitely preferred, if one is to quantitatively establish the morphology of these systems. Some bulk measurements that have been used to complement TEM include, small and ultra-small angle X-ray scattering, SAXS and USAXS, 74 AFM, 75 solid state NMR, 76 infrared spectroscopy, 77 and rheological measurements. 78 Weiss 79 has made a comprehensive study of the intercalation behavior of n-alkylammonium ions into montmorillonite.…”