Scattering methods for determining structure and dynamics of polymer gels

Abstract

Polymer gels are unique materials, which consist of a polymer network swollen in a solvent. The modulus and the overall state of the gel depend on thermodynamic parameters, such as strand length, structure, and chemical compatibility of the solvent. Scattering techniques have been used to study the gel structure and osmotic pressure and are discussed in this Tutorial pedagogically. These techniques are not always straightforward because of trapped inhomogeneities and complicated interactions. Nevertheless, there has been considerable progress in developing analytical tools to determine the internal structure and dynamics of polymer gels. In addition to these tools, we showcase modern spatially resolved techniques, such as Diffusing Wave Spectroscopy, and offer a perspective on similar methods such as Dynamic Small Angle Light Scattering and Differential Dynamic Microscopy, which can be used to study local and interface effects in gel systems as well as any anisotropy. These new tools can fundamentally advance our understanding of local gel dynamics, which have so far been too challenging to observe.