Applications of a continuum model for brush gels

Abstract

Brush gels, defined by their branched molecular architecture, exhibit unique mechanical adaptability and tunable properties. A continuum model is adopted to describe their mechanical behavior, governed by a parameter $\beta$ related to the mean-squared end-to-end distance of the underlying polymer chain, which controls the transition from tensile-dilating to tensile-contracting behavior under uniaxial tension. This and other topological parameters of brush gels can be engineered to produce mechanical behavior like that of linear polymer gels and fibrous gels. Adjustments in branch topology of the polymer, such as grafting density and side-chain length, allow for tuning the stiffness while holding the shape of the force–stretch curve fixed. The rate-dependence of the force–stretch curve is more pronounced under compression due to osmotic effects. Rotational shear tests reveal the impact of chemical potential gradients driven by normal stress variations and it is shown that pre-compression can enhance network stiffness. Furthermore, brush gels exhibit increased resistance to drying-induced volume changes, attributed to their network architecture, which enables rapid equilibration. These findings underscore the potential of brush gels in applications requiring mechanical adaptability and stability under drying conditions.