On Surface-Initiated Atom Transfer Radical Polymerization Using Diazonium Chemistry To Introduce the Initiator Layer

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• 作者：Joseph Iruthayaraj ; Sergey Chernyy ; Mie Lillethorup ; Marcel Ceccato ; Troels R酶n ; Mogens Hinge ; Peter Kingshott ; Flemming Besenbacher ; Steen Uttrup Pedersen ; Kim Daasbjerg
• 刊名：Langmuir
• 出版年：2011
• 出版时间：February 1, 2011
• 年：2011
• 卷：27
• 期：3
• 页码：1070-1078
• 全文大小：948K
• 年卷期：v.27,no.3(February 1, 2011)
• ISSN：1520-5827

文摘

This work features the controllability of surface-initiated atom transfer radical polymerization (SI-ATRP) of methyl methacrylate, initiated by a multilayered 2-bromoisobutyryl moiety formed via diazonium chemistry. The thickness as a function of polymerization time has been studied by varying different parameters such as the bromine content of the initiator layer, polarity of reaction medium, ligand type (L), and the ratio of activator (Cu^I) to deactivator (Cu^II) in order to ascertain the controllability of the SI-ATRP process. The variation of thickness versus surface concentration of bromine shows a gradual transition from mushroom to brush-type conformation of the surface anchored chains in both polar and nonpolar reaction medium. Interestingly, it is revealed that very thick polymer brushes, on the order of 1 渭m, can be obtained at high bromine content of the initiator layer in toluene. The initial polymerization rate and the overall final thickness are higher in the case of nonpolar solvent (toluene) compared to polar medium (acetonitrile or N,N-dimethylformamide). The ligand affects the initial rate of polymerization, which correlates with the redox potentials of the pertinent Cu^II/Cu^I complexes (L = Me₆TREN, PMDETA, and BIPY). It is also observed that the ability of polymer brushes to reinitiate depends on the initial thickness and the solvent used for generating it.