Alper O. Yasar

The generation of desired functional groups on poly(4-vinyl pyridine) particles by post-modification technique for antimicrobial and environmental applications.

Poly(4-vinyl pyridine) (p(4-VP)) particles were synthesized by a simple micro-emulsion polymerization technique using sodium dodecyl sulfate (SDS) as surfactant. The prepared p(4-VP) particles were then treated various modifying agents with different functional groups. The modifying agents used in the modification of p(4-VP) particles are N-alkyl quaternizing agents such as 2-bromo ethanol (-OH), 4-bromo butyronitrile (-CN), and 2-bromoethylamine hydrobromide (-NH2). The functional groups on the modified p(4-VP) particles were confirmed by FT-IR spectrometry and zeta potential measurements. The size of p(4-VP) and modified p(4-VP) particles is between 300 and 700 nm, and the zeta potentials of modified p(4-VP) particles were varied between 2 and 45 mV. Moreover, a second post-modification was carried out on 4-bromo butyronitrile modified p(4-VP) particles by amidoximation. The modified p(4-VP) particles were also tested for their antimicrobial effects against various bacteria such as Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. It was found that p(4-VP) do not posses antimicrobial properties, whereas the modified forms especially p(4-VP)(+) and p(4-VP)(+)-NH3(+) showed highly bactericidal characteristics. Due to the positive charge by means of new functional groups generated on p(4-VP)-based particles by modification, the absorption of oppositely charged reagents such as fluorescein sodium salt (FSS) was increased drastically. For example, the absorption capacity of unmodified p(4-VP) was increased to 93.3, 93.5, and 93.6 form 37.6 mg for p(4-VP)(+), p(4-VP)(+)-NH2, p(4-VP)(+)-NH3(+), respectively. Moreover, upon modification, except Cu(II), Co(II) and Ni(II) absorption capacities were increased from about 15.9, and 22.1 mg to 21.1 and 39,1 mg per gram particles.

Chapter 9 - 0D, 1D, 2D, and 3D Soft and Hard Templates for Catalysis

Abstract Catalytic reactions are generally catalyzed by metal nanoparticles, metal oxides, or their bi- or trimetallic forms with various formulations, morphology, composition, and shapes. The metal nanoparticle catalytic performances are directly related to the surface features of particles such as crystal structure, atomic stacking and order, surface area, roughness and atomic and/or spatial organizations, and the catalyst environments. Its very well-known that the high surface energy of the metal nanoparticles, which is one of the most important challenges to be considered to overcome, leads to aggregation, deactivation, and oxidation problems. Therefore, many templates such as nanoemulsions prepared from surfactant and polymers and nanogels as zero-dimensional (0D) soft templates; cylindrical or tubular natural or synthetic structures derived from again surfactants, polymers, or peptides or self-assembled structures as one-dimensional (1D) templates; graphene oxide, mica, clay, and silicates as two-dimensional (2D) hard templates; and microgel, bulk hydrogel, and cryogels as three-dimensional (3D) soft templates that are used as stabilizing media will be discussed. Regardless of the sizes of templates, various parameters such as morphology, e.g., core-shell, capsules, guiding direction, porosity, and compartmentation features of the templates, have paramount significance on composition, crystallinity, and shape of the resultant nanoparticle to be used as catalyst. Metal nanoparticles, metal oxides, and metal nanoparticles doped with various elements have been extensively investigated due to their unique physical and chemical properties, and even their bi- or trimetallic forms have been under examination due to synergistic potential application of each of the components. The main concern regarding the nanoparticle synthesis is to overcome their agglomeration, due to their high surface area, high energy, and high surface reactivity resulting in strong tendency to aggregate, leading to deactivation and oxidation. There are a variety of methods available in the synthesis of metal nanoparticles to prevent some of these shortcomings with some catalytic performance sacrifices or with some economical infeasibilities. Nevertheless, the key issue with these methods is the control of the particle size and shapes and the morphology and crystallinity. Therefore, a wide range of templates such as nanoemulsions using surfactant and polymers and nanogels as 0D soft templates; cylindrical or tubular natural or synthetic structures derived from again surfactants, polymers, or peptides or self-assembled structures as 1D templates; graphene, mica, clay, and silicates as 2D hard templates; and microgel, bulk hydrogel, and cryogels as 3D soft templates as stabilizing environments and particle compartments will be discussed. In general, polar molecules or polyelectrolytes stabilizers can be used in both controlling the size and preventing the metal nanoparticles from precipitation processes. Water-soluble polymers, including polyelectrolytes, are the commonly employed stabilizing and/or chelating agents in the preparation of metal ultrafine particles.

The preparation of imidazolium based composite polymeric ionic liquid microgels containing Co metal nanoparticles and their use as catalyst in hydrolysis of NaBH4

M efforts have been focused on the development of high-energy-density power source to support the increasing demand of portable devices. Polymer Electrolyte Membrane Fuel Cells (PEMFC) is efficient and clean electrochemical power devices that have the potential for the applications in the energy conversion and storage. The PEMFC can be operated at a low temperature at about 80 C and can be applied to the mobile electric source such as Laptop, Motor vehicles, etc. After the invention of fuel cell by Sir Grove in 1839, Pt-based catalysts were used as the most common electrode materials for the OxygenReduction Reaction (ORR). However, its deficiency and high price drive to develop new non–precious metal catalysts which are potentially less expensive and more abundant. In the year 1964, Jasinski observed catalytic activity of cobalt phthalocyanine to the ORR. Many methods have been tried to create practical Non Precious Metal Catalysts (NPMCs). Many studies have shown that the reaction of the nitrogen atoms and non-precious transition metals into nano carbon materials can improve the electro-catalytic performance. Commonly, nitrogen-doped carbon materials can be fabricated by two methods: Directly doping during the synthesis of carbon materials and by post-treatment of the as-prepared carbon materials with nitrogen precursor. Especially, nitrogen and transition metal containing carbon composites fabricated via pyrolysis of precursors containing metal salts, nitrogen, and macrocyclic compounds have been demonstrated to be active in catalyzing ORR. Transition metals such as Co and Fe to improve the performance will require a robust method for increasing the reactivity of the metal ion through ligation. In this study, we sprayed graphene on Carbon Paper (CP) by spray method. A Cobalt (Co)-based electro catalyst was fabricated by sputter deposition on GO layered CP and then subjected to a heat treatment in an ammonia (NH3) environment. The fabricated Co/N/Go/CP was investigated as an electro-catalyst for ORR in PEMFC by Cyclic Voltammeter (CV) and Electrochemical Impedance Spectroscopy (EIS).W dressing can be developed from traditional passive materials that focused on moisture management and active ingredients delivery in the local wound environment. In this work, new biomaterial wound dressings was developed based on gelatin containing herbal substances (essential oil), a substance from the plant Eupatorium adenophorum Spreng (Crofton weed) that used as traditional wound healers. The E. adenophorum essential oil was first identified the chemical composition by using GC-MS analysis. The principal components of the oil were p-cymene (16.23%), bornyl acetate (11.84%), amorpha-4, 7(11)-diene (10.51%). The hydrogel wound dressing containing essential oil was then characterized for their antibacterial activity against Gram-positive and Gram-negative in order to elucidate their potential for use as antibacterial wound dressings by using agar disk diffusion methods. The result showed that E. adenophorum essential oil and the essential oilloaded gelatin hydrogel inhibited the growth of the test pathogens, Staphylococcus aureus and Staphylococcus epidermidis and increased with increasing the initial amount of essential oil in the hydrogels which confirmed their application as antibacterial wound dressings. The physical properties such as gel fraction, swelling and weight loss behavior, water vapor transmission rate (WVTR), release characteristics and tensile strength were investigated to evaluate the usefulness of hydrogel to wound dressing. Furthermore, the potential use of these wound dressings was further assessed in terms of the indirect cytotoxicity, in vitro attachment and proliferation of dermal human fibroblasts cultured in the hydrogel wound dressings.