Bottlebrush polymers are macromolecules with densely grafted polymeric pendent groups attached to a polymeric backbone. Theses polymers are traditionally prepared using one of three synthetic strategies: grafting-from, grafting-to, and grafting-through. We present here an alternative method of bottlebrush synthesis called transfer-to. The transfer-to method is a hybrid of the grafting-from and grafting-to approaches in which the growing polymer side chains detach from the backbone, propagate freely in solution, and then reattach to the backbone in a chain transfer step. This synthetic approach eliminates looping and bottlebrush coupling that grafting-from can suffer from. To prepare bottlebrush polymers using this method, we have developed a chain transfer agent for reversible addition fragmentation chain transfer (RAFT) polymerization with an orthogonally polymerizable Z-group (CTA1). CTA1 was first polymerized using ring-opening metathesis polymerization (ROMP) with Grubbs’ catalyst to form poly(CTA1). This backbone polymer was then used in the transfer-to synthetic scheme to form large bottlebrush polymers (Mn &gt; 1 MDa). By changing the R group, several different classes of monomers can be effectively polymerized. Lastly, the side chains can be cleaved by aminolysis at the dithiocarbamate linkage to further characterize the molecular weight and molecular weight distribution of the side chains.

Synthesis of bottlebrush polymers using the transfer-to approach

253rd National Meeting (2017)

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