title: Synthesis of cyclopentadienyl capped polyethylene and subsequent block copolymer formation via hetero Diels-Alder (HDA) chemistry.
abstract: In the current contribution it is demonstrated - for the first time - that poly(ethylene) (M(n) = 1,400 as well as 2,800 g  ·  mol(-1) , PDI = 1.2) can be readily equipped with highly reactive cyclopentadienyl (Cp) end groups. The Cp terminal poly(ethylene) can subsequently be reacted in an efficient hetero Diels-Alder (HDA) reaction with macromolecules (poly(isobornyl acrylate) (M(n) = 4,600 g  ·  mol(-1) , PDI = 1.10) and poly(styrene) (M(n) = 6,300 g  ·  mol(-1) , PDI = 1.13) featuring strongly electron withdrawing thiocarbonyl thio end groups, prepared via reversible addition fragmentation chain transfer (RAFT) polymerization employing benzylpyridin-2-yldithioformate (BPDF) as transfer agent. The resulting block copolymers have been analyzed via high-temperature size exclusion chromatography (SEC) as well as nuclear magnetic resonance (NMR) spectroscopy. The current system allows for the removal of the excess of the non-poly(ethylene) containing segment via filtration of the poly(ethylene)-containing block copolymer. However, the reaction temperatures need to be judiciously selected. Characterization of the generated block copolymers at elevated temperatures can lead - depending on the block copolymer type - to the occurrence of retro Diels-Alder processes. The present study thus demonstrates that RAFT-HDA ligation can be effectively employed for the generation of block copolymers containing poly(ethylene) segments.
authors.affiliation: Laboratoire de Chimie Catalyse Polymères et Procédés, Université de Lyon, CPE Lyon, CNRS UMR, Villeurbanne, France.
authors.forename: Edgar
authors.initials: E
authors.lastname: Espinosa
authors.forename: Mathias
authors.initials: M
authors.lastname: Glassner
authors.forename: Christophe
authors.initials: C
authors.lastname: Boisson
authors.forename: Christopher
authors.initials: C
authors.lastname: Barner-Kowollik
authors.forename: Franck
authors.initials: F
authors.lastname: D'Agosto
mesh_terms: D055598:Chemical Phenomena; D015394:Molecular Structure; D020959:Polyethylene / Q000737:chemistry*; D058105:Polymerization; D011108:Polymers / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D011108:Polymers; D020959:Polyethylene