Developing New Methods for the Mono-end Functionalization of Living Ring Opening Metathesis Polymers

Abstract

In this article we present a review of our recent results in one area of research we are involved in. All research efforts in our group focus on functional polymers and new ways of gaining higher levels of control with regard to the placement of functional groups within these polymers. Here, the living ring opening metathesis polymerization (ROMP) will be reviewed for which end-functionalization methods had been rare until very recently. Polymers carrying particular functional groups only at the chain-ends are, however, very interesting for a variety of industrial and academic applications. Polymeric surfactants and polymer–protein conjugates are two examples for the former and polymer-?-sheet-peptide conjugates one example for the latter. The functionalization of macroscopic or nanoscopic surfaces often relies on mono-end functional polymers. Complex macromolecular architectures are often constructed from macromolecules carrying exactly one functional group at their chain- end. The ring opening metathesis polymerization is particularly interesting in this context as it is one of the most functional group tolerant polymerization methods known. Additionally, high molecular weight polymers are readily accessible with this technique, a feature that living radical polymerizations often struggle to achieve. Finding new ways of functionalizing the polymer chain-end of ROMP polymers has therefore been a task long overdue. Here, we present our contribution to this area of research.

Polymers Tailored for Controlled (Bio)degradation Through End-Group and In-Chain Functionalization

“…In order to synthesize functional homopolymer with degradable backbone using ROMP, strained cyclic or bicyclic monomers that can undergo polymerization are required, such as for example unsaturated lactones or cyclic carbonates. So the monomer must contain core (linear polymer backbone) functionality giving rise to polymer structure that can undergo degradation (an acid or enzyme labile functionality such as ester or amide moieties) and with desired monomer or polymer functionality needed to enable polymer diversification [79]. ROMP of unsaturated ε-caprolactone (6,7-dihydro-2(3H)oxepinone, DHO2) initiated by Schrock's Mo-based catalyst, allows to obtain unsaturated degradable polyesters [63Error!…”

Branched Polymers via ROMP of Termimers

“…[1][2][3][4] The ruthenium carbene complexes developed by Grubbs et al show a high tolerance toward polar functional groups. [ 5 ] The preparation of functional polymers can therefore easily be achieved polymerizing functional monomers.…”

“…Over the past two decades many new methods have been developed to introduce functionality during ruthenium catalyzed living ring‐opening metathesis polymerization (ROMP) . The ruthenium carbene complexes developed by Grubbs et al show a high tolerance toward polar functional groups .…”