Temperature-Dependent FTIR (TD-FTIR) Analysis of PEO-b-PCL Self-Nucleation

Controlling crystallization in biomedically-relevant block copolymers such as PEO-b-PCL has potential to tailor degradation and drug release properties. Our previous work has demonstrated that the crystallization sequence in symmetrical PEO-b-PCL copolymers can be switched using selective solvent casting. The crystals' metastabilities are dependent on their nucleation and growth processes. These processes are altered when the crystallization sequence is inverted. We used self-nucleation studies to evaluate these changes in metastability. Because the polymer weight fraction of each block is nearly identical, DSC studies cannot easily identify the block undergoing melting and crystallization events during thermal processing. TD-FTIR provides a unique opportunity to look at how the individual blocks of PEO and PCL are exhibiting thermal transitions during the self-nucleation processes.