title: Mild and modular surface modification of cellulose via hetero Diels-Alder (HDA) cycloaddition.
abstract: A combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and hetero Diels-Alder (HDA) cycloaddition was used to effect, under mild (T ≈ 20 °C), fast, and modular conditions, the grafting of poly(isobornyl acrylate) (M(n) = 9800 g mol(-1), PDI = 1.19) onto a solid cellulose substrate. The active hydroxyl groups expressed on the cellulose fibers were converted to tosylate leaving groups, which were subsequently substituted by a highly reactive cyclopentadienyl functionality (Cp). By employing the reactive Cp-functionality as a diene, thiocarbonyl thio-capped poly(isobornyl acrylate) synthesized via RAFT polymerization (mediated by benzyl pyridine-2-yldithioformiate (BPDF)) was attached to the surface under ambient conditions by an HDA cycloaddition (reaction time: 15 h). The surface-modified cellulose samples were analyzed in-depth by X-ray photoelectron spectroscopy, scanning electron microscopy, elemental analysis, Fourier transform infrared (FT-IR) spectroscopy as well as Fourier transform infrared microscopy employing a focal plane array detector for imaging purposes. The analytical results provide strong evidence that the reaction of suitable dienophiles with Cp-functional cellulose proceeds under mild reaction conditions (T ≈ 20 °C) in an efficient fashion. In particular, the visualization of individual modified cellulose fibers via high-resolution FT-IR microscopy corroborates the homogeneous distribution of the polymer film on the cellulose fibers.
authors.affiliation: Preparative Macromolecular Chemistry, Institut für Technische Chemie und Polymerchemie, Karlsruhe Institute of Technology, Engesserstr 18, 76128 Karlsruhe, Germany.
authors.forename: Anja S
authors.initials: AS
authors.lastname: Goldmann
authors.forename: Thomas
authors.initials: T
authors.lastname: Tischer
authors.forename: Leonie
authors.initials: L
authors.lastname: Barner
authors.forename: Michael
authors.initials: M
authors.lastname: Bruns
authors.forename: Christopher
authors.initials: C
authors.lastname: Barner-Kowollik
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D003500:Cyclization; D008855:Microscopy, Electron, Scanning; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis / Q000379:methods; D013499:Surface Properties; D014965:X-Rays
chemical_list: D002482:Cellulose