Dynamic-Covalent Nanostructures Prepared by Diels-Alder Reactions of Styrene-Maleic Anhydride-Derived Copolymers Obtained by One-Step Cascade Block Copolymerization
Polymers and High Performance Materials
Macromolecular star formation by Diels-Alder chemistry resulted in dynamic nanomaterials capable of reversibly demonstrating the properties of both linear and highly branched macromolecules. Well-defined block copolymers of maleic anhydride (MAn) and styrene [poly(styrene-alt-MAn)-b-polystyrene (P(S-alt-MAn)-b-PS)] were prepared via a one-pot cascade approach by reversible addition-fragmentation chain transfer (RAFT) polymerization. Subsequent ring opening of the anhydride groups in the P(S-alt-MAn) segments by amidation with furfurylamine led to the formation of block copolymers with pendant furan functionality. Diels-Alder reactions of the furan-functional block copolymer with a bismaleimide crosslinker resulted in core-crosslinked stars by an arm-first approach. Star-like structures were also prepared by first allowing the furan-functional block copolymers to pre-assemble into polymeric micelles in a solvent selective for the polystyrene block. Subsequent addition of a bismaleimide and heating to allow the Diels-Alder reaction resulted in core-crosslinked micelles with similar structures to the polymeric stars prepared by the arm-first approach. Regardless of the synthetic approach employed, the thermoreversibility of the Diels-Alder linkages within the cores rendered the stars/crosslinked micelles dynamic-covalent, as demonstrated by their ability to reversibly dissociate back to the individual arms on heating.
Bapat, A. P.,
Ray, J. G.,
Savin, D. A.,
Hoff, E. A.,
Patton, D. L.,
Sumerlin, B. S.
(2012). Dynamic-Covalent Nanostructures Prepared by Diels-Alder Reactions of Styrene-Maleic Anhydride-Derived Copolymers Obtained by One-Step Cascade Block Copolymerization. Polymer Chemistry, 3(11), 3112-3120.
Available at: http://aquila.usm.edu/fac_pubs/7593