Surface morphology of poly(caprolactone)-b-poly(dimethylsiloxane)-b-poly(caprolactone) copolymers: effects on protein...

Certain triblock copolymer surfaces have beneficial blood contacting properties that remain unexplained from a mechanistic perspective. In this study, poly(caprolactone-block-dimethylsiloxane-block-caprolactone) (PCL-b-PDMS-b-PCL) surfaces are characterized by dynamic contact angle analysis, angle-resolved X-ray photoelectron spectroscopy (XPS), and phase detection imaging atomic force microscopy (AFM). Surface morphology of films cast from 10 wt % MEK solutions are found to be semicrystalline possessing spherulites on the micron scale and alternating semicrystalline PCL-rich and amorphous PDMS-rich lamellae on the nanometer scale. Surface enrichment of the lower surface free energy block, PDMS, is observed using angle-resolved XPS but the surface composition still consists of both copolymer blocks. Films cast from 1 wt % solutions showed similar morphologies but incomplete surface coverage. Different textural features of adsorbed fibrinogen layers on coated and uncoated polypropylene are observed. The hypothesis that patterned block copolymer surfaces can affect protein adsorption and thus influence compatibility is partially supported by the findings of this study.