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Effects of carbon nanotubes (CNT) on the dynamic mechanical property, thermal property, and crystal structure of poly(L-lactic acid) (PLLA) were investigated. Dynamic mechanical analysis (DMA) found that CNT via grafting modification with PLLA (CNT-g-PLLA) could result in effective reinforcing effects. Tan d of DMA found that CNT-g-PLLA was compatible with the PLLA matrix, giving a single T g of the composite with a higher CNT-g-PLLA loading giving a higher T g of the composite. Wide angle X-ray diffraction (WAXD) data demonstrated that CNT could assist the disorder-to-order (a 0 -to-a) transition in PLLA crystals but did not lead to a more compact chain packing of the crystal lattice in PLLA composites than in pure PLLA. The equilibrium melting temperature (T 0 m ) obtained from Hoffman-Weeks plots were found to increase with increasing CNT-g-PLLA content. Small angle X-ray scattering data revealed that thicknesses of crystal layer and amorphous layer of PLLA both decreased with increasing CNT contents. V C 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: [145][146][147][148][149][150][151][152] 2010

Multiwalled carbon nanotubes (MWNT) were functionalized with segmented polyurethanes (PU) by the ''grafting to'' approach. Raman and X-ray photoelectron spectroscopy (XPS) spectra show that the sidewalls of MWNTs have been functionalized with acid treatment, and the amount of COOH increases with increasing acid treatment time. FTIR and X-ray diffraction (XRD) spectra confirm that PU is covalently attached to the sidewalls of MWNTs by esterification reaction. Similar to the parent PU, the functionalized carbon nanotube samples are soluble in highly polar solvents, such as dimethyl sulfoxide (DMSO) and N,N-dimethylformamide (DMF). The functionalized acid amount and the grafted PU amount were determined by thermogravimetric analyses (TGA).Comparative studies, based on SEM images between the PU-functionalized and chemically defunctionalized MWNT samples, also reveal the covalent coating character. Dynamic mechanical analysis (DMA) of nanocomposite films prepared from PU and PU-functionalized MWNTs show enhanced mechanical properties and increased soft segment T g . Tensile properties indicate that PU-functionalized MWNTs are effective reinforcing fillers for the polyurethane matrix.

Organic dyes have been synthesized which containing multiple electron donors (carbazole) and electron acceptors (rhodaniline-3-acetic acid) on triphenylamine (TPA). Photophysical, electrochemical, and theoretical computational methods have categorized these compounds. Nanocrystalline TiO2-based dye-sensitized solar cells (DSSCs) are fabricated using these dye molecules as light-harvesting sensitizers. The overall efficiency of sensitized cells is high (4.64%) as compared to a cis-di(thiocyanato)-bis(2,2′-bipyridyl)-4,4′-dicarboxylate ruthenium(II) (N3 dye)-sensitized device (7.83%) fabricated and measured under the same conditions. Both electron donor (carbazole) and acceptor (rhodaniline-3-acetic acid) play a key role in the increased efficiency. One carbazole and two rhodaniline-3-acetic acid-based dye appears to help convey the charge transfer from the excited dye molecules to the conduction band of TiO2, leading to a higher efficiency of the assembled devices using such a dye. Electrochemical impedance measurements support this dye’s effect on enhancing charge transfer of TiO2 (e−). Computation on this CTPAR2 compound also indicates a larger charge transfer efficiency in the electronically excited state.