Binary and ternary blends of polystyrene-block-poly(p-hydroxystyrene) (MW ) 1 × 10 4 -1 × 10 4 ) with various homopolymers were studied. In binary blends, in which the homopolymers poly(ethylene oxide) (PEO), poly(p-vinylpyridine) (PVPy), and poly(n-butyl acrylate) (PnBA) had attractive interactions via hydrogen-bonding with the poly(p-hydroxystyrene) block but were immiscible with the polystyrene block, microphase separation played a dominant role in morphology development. The attractive interaction parameter appeared to be the major factor that influenced the phase separation mechanism. The results obtained with three different molecular weights of PEO suggested that the molecular weight effect was not important when the attractive interaction parameter was sufficiently strong. In PVPy/copolymer blends, microphase separation was also prevalent, but phase separation in PnBA/copolymer blends seemed to follow the macro-micro mechanism. In blends of the diblock copolymer with poly(vinyl methyl ether), which was miscible with both blocks, the latter acted as a polymeric solvent for the copolymer and gave a single-phase mixture when present in sufficient amount. The addition of the block copolymer reduced the domain size in PS/poly(ethyloxazoline) blends. In PS/poly(methyl methacrylate) and PS/poly(n-butyl methacrylate) blends, the morphology changed to a cocontinuous pattern upon incorporation of the copolymer.
Pathogenic bacteria adhesion and formation of biofilm on the implant are the most common reasons for healthcare-associated device failure. Cationic amphiphilic polymer brushes containing covalently linked quaternary ammonium salts (QASs) are considered to be the most promising bactericidal materials, but these surfaces still suffer from incomplete bactericidal ability and serious microorganism accumulation. With this in mind, a novel kind of hierarchical surface integrating both geminized cationic amphiphilic antibacterial upper layer and zwitterionic antifouling sublayer has been developed in this study. Measurements of X-ray photoelectron spectroscopy, spectroscopic ellipsometry, atomic force microscopy, water contact angle, and surface ζpotential were performed to investigate the surface functionalization process. The thicknesses and grafting densities of the pAGC 8 upper blocks have been optimized to avert the mutual interference among different components. The optimal hierarchical surface exhibits an ultrahigh antibacterial activity and a potent self-cleaning functionality against both Staphylococcus aureus and Escherichia coli bacteria, as well as a certain protein repellence ability. Such a novel hierarchical architecture provides innovative guidance for the construction of super-antibacterial and self-cleaning brushes in many biomedical applications.
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