Degrafting of Poly(poly(ethylene glycol) methacrylate) Brushes from Planar and Spherical Silicon Substrates

Abstract

Densely grafted, hydrophilic polymer brushes produced via surface-initiated controlled radical polymerization have been shown to undergo degrafting upon exposure to aqueous media. This degrafting process has been proposed to involve swelling-induced, mechanochemically facilitated hydrolysis of bonds located at the brush–substrate interface. While a number of reports have described degrafting of hydrophilic polymer brushes, only little is known about the key structural parameters of these thin films that dictate this process. Using a series of PPEGMA and PPEGMEMA brushes produced by surface-initiated atom transfer radical polymerization (SI-ATRP), this report investigates the influence of three parameters: (i) the chemical structure of the ATRP initiator, (ii) the molecular weight of the surface-grafted polymer chains, and (iii) surface curvature. Studies performed with PPEGMA and PPEGMEMA brushes grown from substrates modified with different ATRP initiators indicated that hydrolysis of both siloxane as we...