Abstract
Photo-induced copper-mediated radical polymerization is used to synthesize monodisperse sequence defined acrylate oligomers via consecutive single unit monomer insertion reactions and intermediate purification of the compounds by column chromatography or preparative recycling size exclusion chromatography. Monomer conversions are followed during reaction by means of infrared spectroscopy. When reaction conditions are chosen carefully and any residues from chlorinated solvents are avoided, 100% pure Br end capped sequence defined oligomers are obtained, demonstrating the convenience and power of photo-induced copper mediated radical insertion for establishing sequence control. Within this work, a library of sequence defined oligomers containing polar and apolar ester groups have been obtained, and for the first time, perfectly monodisperse acrylate pentamers became accessible from radical insertion reactions.
Highlights
Ever since the development of controlled/living and earlier ionic polymerization techniques[1,2] highly complex polymeric materials have become available
We have used photoCMP as a useful technique to synthesize a library of monodisperse sequence de ned acrylate oligomers via sequential single monomer unit insertion reactions
Oligomers with a sequence of up to 5 monomer units were obtained this way, which marks the current record in sequence de ned (SD) oligomers made via any CRP technology
Summary
Ever since the development of controlled/living and earlier ionic polymerization techniques[1,2] highly complex polymeric materials have become available. The concept was difficult to use for creation of larger oligomers due to the successively more similar radical reactivity of growing macro-RAFT oligomer chains.[31] Using a similar approach, our group demonstrated the synthesis of SUMI oligomers in which up to 4 different acrylate monomers were built in a trithiocarbonate RAFT agent.[32] The statistical nature of the radical insertions was thereby accepted, but a er each insertion reaction the resulting product mixture was puri ed to isolate the desired SUMI product from its by-products (species in which either no monomer or more than one monomer was built in).
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