Quantification of branching in disordered materials

Abstract

ABSTRACT:The phenomenon of structural branching is ubiquitous in a wide array of materials: polymers, ceramic aggregates, polymeric networks, and gels. Branching has a strong influence on the structureproperty relationships of these materials. Despite the interdisciplinary importance and decades of effort, the analytical description and quantification of branching are weak. Existing techniques for polymers based on size exclusion chromatography and rheology are, at best, qualitative, and quantitative characterization techniques such as nuclear magnetic resonance spectroscopy and transmission electron microscopy (for ceramic aggregates) have limitations in providing routine quantification. For ceramic aggregates, theoretical work has dominated, and only a few publications on analytical studies exist to support the theory. Small-angle scattering of X-rays and neutrons can be used to quantify the branch content through application of concepts native to fractal geometry.

Controlling poly(β-amino ester) network properties through macromer branching

“…Polymer branch content can be determined using various techniques such as GPC, NMR, rheology, and small-angle scattering [25]. Based on the structures of the starting reagents, it is anticipated that the macromers will contain short-chain branches as opposed to long-chain branches (molecular weight indistinguishable from the main chain).…”

“…Based on the structures of the starting reagents, it is anticipated that the macromers will contain short-chain branches as opposed to long-chain branches (molecular weight indistinguishable from the main chain). GPC, small-angle scattering, and rheology are techniques that are useful for determining long-chain branching as opposed to short-chain branching [25] and could not be used for macromer characterization in this work. Although high-frequency (188.6 MHz) 13 C NMR can be used to quantify shortchain branching, it is limited to high levels of short-chain branching because it is very difficult to assign chemical shift values to side chains greater than six or more carbon atoms in length [25].…”

Effect of carbon nanofibers on mechanical and electrical behaviors of acrylonitrile‐butadiene rubber composites

“…The mechanism of reinforcing is largely associated with the chemical and physical interactions between the polymer matrix and the filler . Kulkarni et al and Niedermeier et al reported that there are several known mechanisms of filler reinforcement: sorption and chemisorption of the polymer molecules on the filler's surface, occlusion of the polymer macromolecules between the filler's voids, formation of an adhesive layer in the interphase boundary, chemical reactions between the chemical groups of the polymer and the filler, and dissipation of the critical stress in polymer macromolecules by the sliding on the filler's surface. The reinforcing effect of a filler depends on its characteristics, such as size and shape of the particles, specific surface area, surface activity, hydrodynamic effect, tendency to create a structure in the elastomer matrix, and the strength of the polymer‐filler interactions .…”

Investigating the Molecular Architecture of Hyperbranched Polymers

“…[12] Small angle scattering (SAS) of X-rays and neutrons can yield structural information from branched or aggregated systems over multiple size-scales. [13a,13b] In recent works by Beaucage, [14] and Kulkarni and Beaucage, [15] it has been proposed that SAS data could potentially yield topological information from such systems. In this communication, we make an attempt to apply this approach to small angle neutron scattering (SANS) data from the existing literature.…”