Applying Thermosettable Zwitterionic Copolymers as General Fouling-Resistant and Thermal-Tolerant Biomaterial Interfaces

We introduced a thermosettable zwitterionic copolymer to design a high temperature tolerance biomaterial as a general antifouling polymer interface. The original synthetic fouling-resistant copolymer, poly­(vinylpyrrolidone)-<i>co</i>-poly­(sulfobetaine methacrylate) (poly­(VP-<i>co</i>-SBMA)), is both thermal-tolerant and fouling-resistant, and the antifouling stability of copolymer coated interfaces can be effectively controlled by regulating the VP/SBMA composition ratio. We studied poly­(VP-<i>co</i>-SBMA) copolymer gels and networks with a focus on their general resistance to protein, cell, and bacterial bioadhesion, as influenced by the thermosetting process. Interestingly, we found that the shape of the poly­(VP-<i>co</i>-SBMA) copolymer material can be set at a high annealing temperature of 200 °C while maintaining good antifouling properties. However, while the zwitterionic PSBMA polymer gels were bioinert as expected, control of the fouling resistance of the PSBMA polymer networks was lost in the high temperature annealing process. A poly­(VP-<i>co</i>-SBMA) copolymer network composed of PSBMA segments at 32 mol % showed reduced fibrinogen adsorption, tissue cell adhesion, and bacterial attachment, but a relatively higher PSBMA content of 61 mol % was required to optimize resistance to platelet adhesion and erythrocyte attachment to confer hemocompatibility to human blood. We suggest that poly­(VP-<i>co</i>-SBMA) copolymers capable of retaining stable fouling resistance after high temperature shaping have a potential application as thermosettable materials in a bioinert interface for medical devices, such as the thermosettable coating on a stainless steel blood-compatible metal stent investigated in this study

Surfactant-Enriched ZnO Surface via Sol–Gel Process for the Efficient Inverted Polymer Solar Cell

In this study, we demonstrate that the top surface is enriched by surfactants, tetraoctylammonium bromide, and cetylpyridinium bromide (CPB), in the sol–gel ZnO, being evidenced by the Br depth profile of electron spectroscopy for chemical analysis data. X-ray photoelectron spectroscopy results showed the formation of Zn–Br bonding due to the oxygen defects occupied by Br at the surfactant-enriched ZnO surface. The surfactant-enriched ZnO surface possessed a smoother surface and more hydrophobicity than the pristine ZnO from the experimental results of atomic force microscopy and contact angle, respectively. On the basis of ultraviolet photoelectron spectroscopy data, the work function slightly reduced due to the dipole built-up by the electrostatic force between Br^– and N⁺ to enhance the electron extraction ability. The improved properties benefited the power conversion efficiency (PCE) of bulk-heterojunction polymer solar cells (PSCs) by spin-coating the active layer on the surfactant-enriched ZnO surface. The inverted PSCs with the surfactant-enriched ZnO surface showed the highest PCE of 9.55% for the CPB case, in comparison with the pristine ZnO surface (8.08% PCE). This study discloses that turning the ZnO surface is easily achieved by the addition of surfactants with different molecular structures in the sol–gel ZnO for high performance polymer solar cells

Core Dominated Surface Activity of Core–Shell Nanocatalysts on Methanol Electrooxidation

The activity of core–shell nanoparticles (NCs) in electrooxidation of methanol (MOR) was found to be dependent on the crystalline structure of the core and the lattice strain at the core–shell interface. Ru-core and Pt-shell NCs delivered 6.1-fold peak MOR current density at −135 mV than Pt NCs, while the Co-core and Pt-shell NCs showed a 1.4-fold peak MOR current density at 280 mV. The current density is improved by the compressive lattice strain of the surface that is caused by the lattice mismatch between the Pt shell and the Ru core. For Co-core NCs, the enhancement results from the ligand effect at surface Pt sites. In addition, the Ru-core NCs maintained a steady current density of 0.11 mA cm^–2 at 500 mV in a half-cell system for 2 h, which is 100-fold higher than that of Pt NCs and Co-core NCs. These results provide mechanistic information for the development of fuel cell catalysts along with reduced Pt utilization and programmable electrochemical performance