Chemical shield effect of metal complexation on seeded growth of poly(ε-caprolactone) core-forming blends

Abstract

Seeded growth approach is an ambient temperature, living crystallization-driven self-assembly (CDSA) process of crystallizable block copolymers (BCPs) in selective solvents, which enables to the formation of micelle particles in a controllable and designable way. However, the seeded growth of crystallizable BCPs under spatial restriction exerted by external interactions is rarely explored. In present work, the seeded growth of polymer blend involving homopolymer and BCP is extensively studied with the unique complexation interaction between metal ions and poly(4-vinylpyridine) (P4VP) corona segments. Incorporation of certain amount of metal ions with 1D PCL-b-P4VP (PCL = poly(ε-caprolactone)) seeds would result in the inactivity of crystalline seeds. This chemical shield effect is largely related to the binding strength and molar ratio of metal ion to 4VP groups. The metal complexation between Cu2+ and PCL/PCL-b-P4VP blend unimer that is for seeded growth would also lead to the failure of successful epitaxial growth, which is caused by the cross-linking effect of P4VP segments in the presence of metal ions. Nevertheless, this cross-linking effect could be efficiently removed by adding a ligand that has a much stronger binding strength with Cu2+. Our finding provides a deep understanding of metal complexation on the seeded growth of crystallizable BCPs, and also provides useful information about the chemical shield effect exerted by corona conformation that will guide future studies of living CDSA.