•A simple aqueous-based route was developed to immobilize ATRP initiators, Br, onto the surface of SEBS.•SEBS surface was manipulated with surface-initiated ATRP method for the first time.•Effective initiation sites were determined to be CBr bonds directly connected to benzene rings of SEBS.•The surfaces of modified SEBS with well-defined polymer brushes exhibited high hemocompatibility.Surface-initiated atom transfer radical polymerization (SI-ATRP) is a versatile tool for surface functionalization in a well-controlled manner. However, surface modification of styrenic thermoplastic elastomers (STPEs) faces a great challenge because immobilization of typical ATRP initiators onto STPEs needs to be carried out in organic solvent, which dissolves and destroys the STPEs film. In this work, a simple aqueous-based route is developed to immobilize ATRP initiators, Br, onto the surface of styrene-b-(ethylene-co-butylene)-b-styrene elastomer (SEBS), chosen as a model copolymer of STPEs. In such a way, functional polymer brushes of ethylene glycol methyl ether methacrylate (OEGMA) are successfully prepared from the surface of SEBS. Kinetic investigations show an approximately linear relationship between grafting density and reaction time, indicating the growth of chains is coincident with a “controlled” process. CBr bonds directly connected to benzene rings on the SEBS-Br surfaces are demonstrated to be effective initiation sites for SI-ATRP. The even coverage of the surface by well-defined P(OEGMA) brushes enable SEBS films to exhibit excellent resistance to protein adsorption and platelet adhesion as well as low hemolysis ratio. This work not only manipulates the SEBS surface to substantially improve its biocompatibility, but paves a way to facilitate SI-ATRP on the surface of styrene-based block copolymers (SBCs).Graphical abstract

Adhesive force exists between polymer nano/microfibers. An elaborate experiment was performed to investigate the adhesion between polymer nano/microfibers using a nanoforce tensile tester. Electrospun polycaprolactone (PCL) fibers with diameters ranging from 0.4–2.2 μm were studied. The response of surface property of electrospun fiber to the environmental conditions was tracked by FTIR and atomic force microscopy (AFM) measurements. The effect of temperature on molecular orientation was examined by wide angle X-ray diffraction (WAXD). The adhesive force was found to increase with temperature and pull-off speed but insensitive to the change of relative humidity, and the abrupt increase of adhesion energy with temperature accompanied by a reduced molecular orientation in the amorphous part of fiber was observed. Results show that adhesion is mainly driven by van der Waals interactions between interdiffusion chain segments across the interface.