Electroless deposition of copper on polyimide films modified by surface graft copolymerization with nitrogen-containing vinyl monomers

Electro- and Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes

The synthesis of renewable fuels from abundant water or the greenhouse gas CO2 is a major step toward creating sustainable and scalable energy storage technologies. In the last few decades, much attention has focused on the development of nonprecious metal-based catalysts and, in more recent years, their integration in solid-state support materials and devices that operate in water. This review surveys the literature on 3d metal-based molecular catalysts and focuses on their immobilization on heterogeneous solid-state supports for electro-, photo-, and photoelectrocatalytic synthesis of fuels in aqueous media. The first sections highlight benchmark homogeneous systems using proton and CO2 reducing 3d transition metal catalysts as well as commonly employed methods for catalyst immobilization, including a discussion of supporting materials and anchoring groups. The subsequent sections elaborate on productive associations between molecular catalysts and a wide range of substrates based on carbon, quantum dots, metal oxide surfaces, and semiconductors. The molecule-material hybrid systems are organized as "dark" cathodes, colloidal photocatalysts, and photocathodes, and their figures of merit are discussed alongside system stability and catalyst integrity. The final section extends the scope of this review to prospects and challenges in targeting catalysis beyond "classical" H2 evolution and CO2 reduction to C1 products, by summarizing cases for higher-value products from N2 reduction, C x>1 products from CO2 utilization, and other reductive organic transformations.

Solar Hydrogen Production Using Molecular Catalysts Immobilized on Gallium Phosphide (111)A and (111)B Polymer-Modified Photocathodes

We report the immobilization of hydrogen-producing cobaloxime catalysts onto p-type gallium phosphide (111)A and (111)B substrates via coordination to a surface-grafted polyvinylimidazole brush. Successful grafting of the polymeric interface and subsequent assembly of cobalt-containing catalysts are confirmed using grazing angle attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Photoelectrochemical testing in aqueous conditions at neutral pH shows that cobaloxime modification of either crystal face yields a similar enhancement of photoperformance, achieving a greater than 4-fold increase in current density and associated rates of hydrogen production as compared to results obtained using unfunctionalized electrodes tested under otherwise identical conditions. Under simulated solar illumination (100 mW cm(-2)), the catalyst-modified photocathodes achieve a current density ≈ 1 mA cm(-2) when polarized at 0 V vs the reversible hydrogen electrode reference and show near-unity Faradaic efficiency for hydrogen production as determined by gas chromatography analysis of the headspace. This work illustrates the modularity and versatility of the catalyst-polymer-semiconductor approach for directly coupling light harvesting to fuel production and the ability to export this chemistry across distinct crystal face orientations.

Improving the Efficiency of Organic Solar Cells upon Addition of Polyvinylpyridine

We report on the efficiency improvement of organic solar cells (OPVs) based on the low energy gap polyfluorene derivative, APFO-3, and the soluble C₆₀ fullerene PCBM, upon addition of a residual amount of poly (4-vinylpyridine) (PVP). We find that the addition of 1% by weight of PVP with respect to the APFO-3 content leads to an increase of efficiency from 2.4% to 2.9%. Modifications in the phase separation details of the active layer were investigated as a possible origin of the efficiency increase. At high concentrations of PVP, the blend morphology is radically altered as observed by Atomic Force Microscopy. Although the use of low molecular weight additives is a routine method to improve OPVs efficiency, this report shows that inert polymers, in terms of optical and charge transport properties, may also improve the performance of polymer-based solar cells.

Surface modification of polymers for biocompatibility via exposure to extreme ultraviolet radiation

Polymeric biomaterials are being widely used for the treatment of various traumata, diseases and defects in human beings due to ease in their synthesis. As biomaterials have direct interaction with the extracellular environment in the biological world, biocompatibility is a topic of great significance. The introduction or enhancement of biocompatibility in certain polymers is still a challenge to overcome. Polymer biocompatibility can be controlled by surface modification. Various physical and chemical methods (e.g., chemical and plasma treatment, ion implantation, and ultraviolet irradiation etc.) are in use or being developed for the modification of polymer surfaces. However an important limitation in their employment is the alteration of bulk material. Different surface and bulk properties of biomaterials are often desirable for biomedical applications. Because extreme ultraviolet (EUV) radiation penetration is quite limited even in low density mediums, it could be possible to use it for surface modification without influencing the bulk material. This article reviews the degree of biocompatibility of different polymeric biomaterials being currently employed in various biomedical applications, the surface properties required to be modified for biocompatibility control, plasma and laser ablation based surface modification techniques, and research studies indicating possible use of EUV for enhancing biocompatibility.

Fabrication and Characterization of Cu-Plated Fine Pitch Patterns on Flexible Polyimide

The thin flexible Polyimides (PI) films have desirable properties for use in the electrical and electronics industry because their good thermal stability, high flexibility, low dielectric constants, excellent mechanical strength, low loss tangent, low relative permittivity and electrical insulating properties. In order to determine the process window of the surface metallization of PI, the fine traces with 50 micron pitch (25micron line /space) built on a flexible 50 micron thick PI film using wet fabrication process are reported in this paper. The thick copper (Cu) film was obtained from the Cu plating process using evaporated thin film of Cu as the adhesion layer. The fabricated fanout fine patterns are further investigated using scanning electron microscope (SEM), energy-dispersive spectrometry (EDS) and X-ray spectrometry technologies. The experiment is conducted to study the effect of the process parameters on the Cu film surface properties. The results obtained in this work can be applied to the fabrication of flexible microelectronic devices.

Structure-activity relationship for quaternary ammonium compounds hybridized with poly(methyl methacrylate)

Hybrid films from poly (methylmethacrylate) (PMMA) and dioctadecyldimethylammonium bromide (DODAB), cetyltrimethylammonium bromide (CTAB), or tetrapropylammonium bromide (TPAB) were characterized by determination of wettability, ellipsometry, atomic force microscopy, active compounds diffusion to water, X-ray photoelectron spectroscopy (XPS) with determination of atomic composition on the films surface, and biocidal activity against Pseudomonas aeruginosa or Staphylococcus aureus. QAC mobility in the films increased from DODAB to CTAB to TPAB. Diffusion and optimal hydrophobic-hydrophilic balance imparted the highest bioactivity to CTAB. DODAB sustained immobilization at the film surface killed bacteria upon contact. TPAB ability to diffuse was useless because of its unfavorable hydrophobic-hydrophilic balance for bioactivity.