Dithiol-yne Polymerization: Comb Polymers with Poly(ethylene glycol) Side chains

Recently dithiol-yne click chemistry and its role in the formation of cross-linked polymer networks and postpolymerization functionalizations has been studied; however, no research has considered this technique to form comb polymers with regular side chains. Here we report the first example of a grafted-through step-growth comb polymer via the utilization of dithiol-yne “click chemistry”. First, we exhibited the efficacy of this reaction to produce modest-molecular-weight combs (M_n = 16 kDa). Second, we displayed the ability to precisely control the length of the side chains of these combs along with the space between the side chains by using various molecular weights of propargylated PEG chains and a variety of alkanedithiol backbone spacers. The primary species of these reactions were macrocyclic comb polymers, with a smaller amount of dithiol-terminated comb polymers.