FIG. 3.

Effects of surface modification on UX-PCL topography. (A) Schematic of water contact angle (WCA) measurement (red and yellow arrows: two perpendicular directions the WCA measurement followed; double-headed arrows: ridge direction). (B) WCA of HP- and UX-PCL before hydrolysis. UX-PCL revealed an anisotropic surface hydrophilicity, with a larger WCA in the perpendicular direction than that along the parallel direction. ***Represents the significant difference compared with the WCA in parallel direction (n=3; ***p<0.001). (C) WCA of HP- and UX-PCL after hydrolysis for different time. Alkaline hydrolysis increased the surface hydrophilicity of PCL films, and enlarged the anisotropy of surface hydrophilicity of UX-PCL with raised WCA difference between the parallel and perpendicular directions (n=3). (D) Morphology of UX-PCL after hydrolysis for different time. FESEM images showed the shapes of micro-ridge/grooves of UX-PCL being well maintained over the investigating period (scale bar=10 μm). Color images available online at www.liebertpub.com/tec