Coil-Helix and Sheet-Helix Block Copolymers via Macroinitiation from Telechelic ROMP Polymers

Coil-helix and sheet-helix block copolymers are synthesized by combining the ring-opening metathesis polymerization (ROMP) of norbornene or paracyclophanediene with the anionic polymerization of phenyl isocyanide. Key to the design is the use of an l-ethynyl palladium (II) functionalized chaintransfer agent (CTA) that can be exploited in a stepwise manner for the termination of ROMP and the initiation of the anionic polymerization. Both the coil-and sheet-macroinitiators, and the ensuing covalent block copolymers, are analyzed using 1 H NMR spectroscopy and gel-permeation chromatography. In all cases, the Pd-end group is maintained and all polymers demonstrate a monomodal distribution with dispersities (-D) of 1.1-1.4. The resulting helix-coil and helix-sheet block copolymers formed by the macroinitiation route still demonstrate their intrinsic properties (fluorescence, preferential helixsense). (C) 2017 Wiley Periodicals, Inc.