ROMP Copolymers for Orthogonal Click Functionalizations

The ring-opening metathesis polymerization using ruthenium carbene initiators developed by Grubbs et al. is one of the most functional group tolerant living polymerization methods known. One of the most used postpolymerization functionalization methods used today is the copper-catalyzed 1,3-dipolar cycloaddition between alkynes and organic azides. Organic azides are, however, not tolerated by ruthenium carbene initiators, and nonprotected alkynes have been shown to slow down the propagation reaction or react with the propagating species leading to broad molecular weight distributions. Here we report the copolymer synthesis of three orthogonally functionalizable monomers: one carrying an activated pentafluorophenyl ester, one a maleimide unit, and a third one a trialkylsilyl-protected alkyne. From these monomers, statistical terpolymers as well as diblock copolymers were synthesized with different molecular weights and monomer compositions or block ratios, respectively. Excellent control over molecular weight and molecular weight distribution could be achieved using Grubbs' first-generation ruthenium carbene initiator. Herein we present the synthesis and orthogonal triple postpolymerization functionalization of these copolymers.