(45b) Properties of Cyclic, Linear, and Topological Blend Films of Poly(e-caprolactone)

While the crystallization of linear and branched polymers has received much attention in the literature due to the importance of polymers like linear poly(ethylene glycol) to the biological sciences and branched polyethylenes to the commodity polymers market, the effect of ring architecture on polymer crystallization is less well understood, in part due to the challenges associated with synthesizing well-defined cyclic polymers. However, recent advances have enabled the synthesis of cyclic polymers with exact linear analogues using an azide-alkyne “click” reaction for ring closure and prompted additional research into the properties of cyclic polymers. In our work, we focus on how the linear versus cyclic polymer architecture affects thin film properties such as film stability against dewetting, crystallization kinetics, and crystalline morphology. In addition to examining pure linear and cyclic materials, we also explore systematically these properties in topological blends. As a model system, we have chosen poly(ε-caprolactone) (PCL), a semi-crystalline, aliphatic polyester that has applications in biomedical engineering including anti-adhesion biomaterial films, drug delivery media, and others. In comparing pure linear to pure cyclic materials, we find that molecular weight, film thickness, and processing temperatures are important to the comparison, making results on cyclic versus linear polymers difficult to generalize. Like some of the physical properties reported for bulk topological blends (e.g., viscosity), we find that the thin film physical properties of blends are usually non-additive.