Efficient Switching of RAFT to Hydroxy Capped Polymers as Versatile Scaffolds for Block Copolymer Synthesis

• Applicant: Professor Dr. Christopher Barner-Kowollik
• Subject Area: Preparatory and Physical Chemistry of Polymers
• Term: from 2010 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 165300460

• Final Report Year: 2013

Final Report Abstract

As a summary of the project, it can be stated that the thiocarbonyl thio to OH switch of RAFT based polymers functions well for most polymer and RAFT agent classes. The resulting sulfur-free narrow dispersity block copolymers can be efficiently employed in ROP chain extension reactions to prepare linear and star block copolymers as well as polyaddition polymers based on RAFT segments, which can be readily imaged with two dimensional chromatographic techniques. The introduction of cyclopentadienyl functionality into polymers is best conducted via a –Br to Cp switch based on nickelocene, rather than by transforming OH terminal polymers via a tosylation and subsequent nucleophilic substitution by Cp-. The block copolymer formation based on Cp terminal units with activated dithioester capped macromolecules proceeds fast and efficient, while the preparation of star polymers via such a route is beset with end group fidelity limitations.

Publications

• "Facile Conversion of RAFT Polymers into Hydroxyl Functional Polymers: A Detailed Investigation of Variable Monomer and RAFT Agent Combinations". Polym. Chem. 2010, 1, 634-644
  Dietrich, M.; Glassner, M.; Gruendling, T.; Schmid, C.; Falkenhagen, J.; Barner- Kowollik, C.
  
• "An Efficient Avenue to Poly(styrene)-block-(-Caprolactone) Polymers via Switching from RAFT to Hydroxyl Functionality: Synthesis and Characterization" J. Polym. Sci. – Polym. Chem. 2011, 49, 1-10
  Schmid, C.; Falkenhagen, J.; Barner-Kowollik, C.
  
• "Visualizing the Efficiency of Rapid Modular Block Copolymer Construction". Polym. Chem. 2011, 2, 126-136
  Inglis, A. J.; Barner-Kowollik, C.
  
• "Efficient Switching of RAFT to Hydroxyl Capped Polymers as a Versatile Scaffold for Block Copolymer Synthesis". Dissertation, 2012
  Christina Schmid
  
• "In-Depth LCCC-(GELC)-SEC Characterization of ABA Block Copolymers Generated by a Mechanistic Switch from RAFT to ROP". Macromolecules 2012, 45, 87-99
  Schmid, C.; Weidner, S.; Falkenhagen, J.; Barner-Kowollik, C.
  
• "Multi-Block Polyurethanes via RAFT End-group Switching and their Characterization by Advanced Hyphenated Techniques". Macromolecules 2012, 45, 6353−6362
  Schmid, C.; Falkenhagen, J.; Beskers, T. F.; Nguyen, L.-T. T.; Wilhelm, M.; Du Prez, F. E.; Barner-Kowollik, C.