title: High- versus low-quality graphene: a mechanistic investigation of electrografted diazonium-based films for growth of polymer brushes.
abstract: Electrografting using aryldiazonium salts provides a fast and efficient technique to functionalize commercially available 3-5 layered graphene (vapour-deposited) on nickel. In this study, Raman spectroscopy is used to quantify the grafting efficiency of cyclic voltammetry which is one of the most versatile, yet simple, electrochemical techniques available. To a large extent the number of defects/substituents introduced to the basal plane of high-quality graphene by this procedure can be controlled through the sweeping conditions employed. After extended electrografting the defect density reaches a saturation level ( ∼ 10(13) cm(-2)) which is independent of the quality of the graphene expressed through its initial content of defects. However, it is reached within fewer voltammetric cycles for low-quality graphene. Based on these results it is suggested that the grafting occurs (a) directly at defect sites for, in particular, low-quality graphene, (b) directly at the basal plane for, in particular, high-quality graphene, and/or (c) at already grafted molecules to give a mushroom-like film growth for all films. Moreover, it is shown that a tertiary alkyl bromide can be introduced at a given surface density to serve as radical initiator for surface-initiated atom transfer radical polymerization (SI-ATRP). Brushes of poly(methyl methacrylate) are grown from these substrates, and the relationship between polymer thickness and sweeping conditions is studied.
authors.forename: Mie
authors.initials: M
authors.lastname: Lillethorup
authors.forename: Mikkel
authors.initials: M
authors.lastname: Kongsfelt
authors.forename: Marcel
authors.initials: M
authors.lastname: Ceccato
authors.forename: Bjarke B  E
authors.initials: BB
authors.lastname: Jensen
authors.forename: Bjarke
authors.initials: B
authors.lastname: Jørgensen
authors.forename: Steen U
authors.initials: SU
authors.lastname: Pedersen
authors.forename: Kim
authors.initials: K
authors.lastname: Daasbjerg