Synthesis and Assembly Behavior of Heteronucleobase-Functionalized Poly(epsilon-caprolactone)

Abstract

The heteronucleobase (adenine and uracil)-functionalized poly(epsilon-caprolactone) (A-PCL-U) possessing supramolecular structure has been successfully synthesized through the combination of ring-opening polymerization and Michael addition reaction. Attachment of multiple hydrogen-bonding units to chain ends of PCL results in phase separation and substantial increase in the viscosity. The association constant (K(a)) between adenine and uracil groups of A-PCL-U calculated from NMR measurement is 18.9 M(-1). XRD and DSC analyses indicate that the crystalline structure of the A-PCL-U is changed to some extent due to phase segregation as compared to the PCL homopolymer. The AFM micrograph demonstrates that phase segregation is formed from the hard nucleobase chain ends and soft poly(epsilon-caprolactone) chains of the supramolecular complex.