Reversible addition fragmentation transfer (RAFT) polymerization of a ?5-cyclopentadienyl-cobalt-?4-cyclobutadiene (CpCoCb) containing monomer under a variety of experimental conditions was examined (e.g. different solvents, temperatures, RAFT agents, concentrations, and [RAFT agent]/[initiator] ratios). In all cases the results revealed that although the monomer was being consumed over the course of the reaction (determined by 1H NMR spectroscopy), there was no increase in the polymer's molecular weight (determined by GPC analysis). As the polymers chain grow to an oligomeric stage (DPn~ 10), they take on tight coil morphology hindering the approach of the sterically demanding CpCoCb containing monomer, resulting in premature termination/chain transfer reactions instead of increase in the polymers' chain length. To address this problem a smaller monomer, methyl acrylate (MA), was copolymerized along with the bulky monomer to act as a spacer providing the necessary space for the approach of another Co-containing monomer. This copolymerization results in a random copolymer with drastic improvement in the polydispersity and the molecular weight of the end material. Furthermore, the random copolymer was used as a macro-RAFT agent to prepare block copolymers, with excellent control over the polymers' molecular weight allowing for an examination of their solid-state self-assembly .

Homo- and diblock copolymers derived from a mixed sandwich cobaltocene: Overcoming a tight coil to give a real �Co� polymer

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.