Mechanochemistry of Polymer Brushes

Abstract

Densely grafted polymer brushes prepared by surface-initiated polymerization (SIP) represent a versatile platform to engineer surface and interface properties. At high grafting densities, surface tethered polymer chains are forced into an extended chain conformation, which can impart these films with appealing materials properties such as low friction or efficient non-biofouling properties. The extended chain conformation of densely grafted polymer chains can also influence their chemical reactivity, in particular in close proximity to the polymer brush–substrate interface. This chapter provides an overview of recent efforts aiming at investigating detachment or degrafting of densely grafted hydrophilic polymer brushes from substrates upon exposure to aqueous media. The collective results from these reports suggest that swelling-induced stretching of such surface-attached polymers activates mechanochemical bonds near the brush–substrate interface and facilitates chain cleavage. Understanding the mechanochemistry of polymer brushes may provide novel opportunities to design robust, durable polymer brush films or, alternatively, systems that are designed to degraft on-demand.

Swelling-Activated, Soft Mechanochemistry in Polymer Materials

“…The formation of wrinkled structures was observed by scanning electron microscopy (SEM) analysis (Figure C). Since then, many reports of swelling-induced degrafting of hydrophilic polymer brushes have been published and can be found in recent reviews. −, Degrafting of hydrophilic brushes not only occurs upon incubation in liquid water but has also been observed upon exposure to humid air . The rate of degrafting was increased with more hydrophilic polymers and higher relative humidity.…”