No abstract

Agarose, ι-, κ-, and λ-carrageenans, and xanthan gum in aqueous solutions interacted with single-walled carbon nanotubes (SWCNTs) as proven by their wetting in solution and by the microRaman spectroscopy, rheological studies, and differential scanning calorimetry. The investigations provided evidence that the effect of complexation of polysaccharides was independent of the possibility of the formation of helical complexes. Complexation involved, to a certain extent, interactions between hydrophobic surface of nanotubes and hydrophobic sides of the saccharide units of polysaccharides. However, clathration of nanotubes in the polysaccharide matrices was also essential. Formation of the clathrate cages involved intra-and intermolecular hydrogen bonds within polysaccharides.ODDZIA£YWANIA POLISACHARYDÓW ANIONOWYCH Z NANORURKAMI WÊGLOWYMI Streszczenie -Agaroza, ι-, κi λkarageny oraz guma ksantanowa (wzór I) w roztworze wodnym oddzia³uj¹ z jednooeciennymi nanorurkami wêglowymi, co potwierdzono analizuj¹c widma Ramana oraz wyniki badañ reologicznych i skaningowej kalorymetrii ró¿nicowej (tabela 1 i 2). Badania dostar-czy³y dowodów na to, ¿e efekt kompleksowania polisacharydów nie zale¿y od mo¿liwooeci otaczania nanorurek helisami polisacharydowymi. Kompleksowanie polega w pewnej mierze na oddzia³ywaniach miêdzy hydrofobow¹ stron¹ merów polisacharydów (rys. 2), a hydrofobow¹ powierzchni¹ nanorurek. Jednak¿e istotne jest te¿ klatratowanie nanorurek w matrycy polisacharydowej. Klatki tworz¹ siê dziêki zarówno wewn¹trz-jak i miêdzycz¹steczkowym oddzia³ywaniom polisacharydów za pooerednictwem wi¹zañ wodorowych. S³owa kluczowe: agaroza, guma ksantanowa, karageny, jednooecienne nanorurki wêglowe, kompleksy polisacharydów z nanorurkami wêglowymi.

Closed-end single-walled carbon nanotubes were wetted in aqueous solutions of monosaccharides, forming weak surface complexes, as proven by the estimation of the content of monosaccharides in complexes isolated from aqueous solutions. The complexation was confirmed by micro-Raman spectroscopy. The Gaussian 03 (Molecular Mechanics UFF method) computations of total energy of the single-walled carbon nanotube-monosaccharides inclusion and surface complexes showed that inclusion complexes should be more stable than corresponding surface complexes. Computed total energies for particular complexes pointed to a lack of preferences for the formation of complexes with either alpha- or beta-tautomers and either pyranoses or furanoses. The forms preferred in the formation of the surface complexes usually differ from these favored in the formation of the inclusion complexes.

In the present paper, the combustion synthesis processes of the system of Fe based composites, mainly containing Fe-Ti-C, under an electric field was studied by using a Gleeble 1500D thermal simulation instrument. The results showed that there was a great change in temperature inside the sample under rather low temperature, compared with that in the self-propagating high temperature synthesis (SHS) processes. This indicated that a reaction may occur, which led to a great deal of heat release. Analyses by X-ray diffraction proved that the microstructures of the sample after combustion consist of TiC, a-Fe and a little Fe 2 Ti. Therefore, it was demonstrated that Fe/TiC system can be synthesised in an electric field, even under low temperature.

Among new energy systems, fuel cells are electrochemical devices transforming chemical energy directly into electrical energy. In our previous works, MWCNTs (the multi walled carbon nanotubes) supported palladium anodic electrocatalysts for DFAFCs (direct formic acid fuel cells) have been studied. MWCNTs can be modified by appropriate oxides, for example, cerium oxide, zirconium oxide and N-doped titanium dioxide, to enhance the electrocatalytic performance of the catalysts. But the oxides and the defects of the acid oxidized MWCNTs, denoted as AO-MWCNTs, can cause the electron capture and reduce both the catalyst conductivity and the catalysts activity. In order to improve the conductive properties of the support, in the present work a conductive polymer was introduced to modify the surface of carbon nanotubes. PANI (polyaniline) has a long-chain structure and conjugated structure and exhibits good conductivity, high stability, and is non-toxic. After PANI modification, AO-MWCNTs can provide efficient electronic conduction network. In this study, PANI modified AO-MWCNTs were prepared via polymerization process. AO-MWCNTs were homogeneously coated with PANI to obtain composite with weight ratio 50:50 PANI to MWCNTs. The thickness of the PANI layer was 4-9 nm. It was shown that the photosynthesis process is a better method to reduce Pd on PANI/AO-MWCNTs than by using NaBH 4 . By adjusting pH value to 9, during preparation of Pd/PANI/AO-MWCNTs composites by X-ray irradiation process, smaller Pd particles were obtained and PANI deprotonation was avoided which explains better activity of this composite in formic acid electro oxidation.