(653e) Hierarchical Crystallization Processes in Double-Crystalline PEO-B-PCL Copolymers

Hierarchical assembly in block copolymers (BCPs) is a critical process and structural component for tailoring macroscopic properties in these diverse materials. Crystallization in BCPs has been studied under a variety of conditions. BCPs that have two crystalline blocks provide an opportunity to tailor the crystallization of one or both of the blocks for different applications. In poly(ethylene oxide)-b-poly(ε-caprolactone) (PEO-b-PCL), the transition temperatures for the two blocks are similar. This feature allows for a diverse and robust set of parameters, such as weight fraction, thermal history, casting solvent, aging or annealing conditions, etc., to tailor the crystalline structure. PCL contains ester bonds capable of hydrolytic cleavage, and hydrophilic PEO promotes water uptake better than hydrophobic PCL. Therefore, crystallinity of each domain influences water uptake or degradation in PEO-b-PCL films. We have shown that crystallization order and crystallinity are manipulated using different film preparation conditions. The next steps are to connect structure-property relationships in PEO-b-PCL films with degradation and drug release rates.