Self-Nucleation Behavior in PEO-b-PCL Copolymers*

Controlling crystallization in biomedically-relevant block copolymers such as PEO-b-PCL has potential to tailor degradation and drug release properties. Recent studies have shown that the crystallization processes in PEO-b-PCL copolymers are impacted by thermal and casting procedures. Specifically, the crystallization order can be switched due to solvent-polymer interactions during drying. The stability of this unique crystal sequence was analyzed here using self-nucleation studies. Symmetric and asymmetric PEO-b-PCL samples were cast from solvent that induces PEO as the initial crystallizing block. The copolymer's self-nucleation behavior as-cast or from the melt depends on the crystallization order. This technique provides the possibility to tune the crystallinity of each block using post-casting thermal treatment.