A novel full-conjugated 4-(2,2′:6′,2′′-terpyrid-4′-yl) benzenediazonium tetrafluoroborate (diazo-tpy) was synthesized and used for surface modification of materials, such as quartz wafers, ITO glass, silicon, and multiwalled carbon nanotubes (MWCNTs). Under UV irradiation, the diazonium group of diazo-tpy is decomposed and the residual terpyridine group is covalently anchored to the surface of substrates. The obtained tpy-modified MWCNTs (tpy-MWCNTs) have good solubility in common organic solvents. TGA and HRTEM analyses confirmed that terpyridine groups have been symmetrically grafted on MWCNTs. The thickness of the tpy-modified monolayer is about 2.3 nm, which is approximately 2 times the axial length of the 4-(2,2′:6′,2′′-terpyrid-4′-yl)phenyl group. The introduction of terpyridine groups on the surface of MWCNTs provides a coordination site to complex with metal ions. Multilayer films were fabricated from tpy-MWCNTs and ruthenium ions [Ru(III)] via the layer-by-layer self-assembled (LBL SA) technique on the tpy-modified quartz wafer, ITO glass, or silicon. The UV−vis results indicate that (1) Ru(III)-tpy-MWCNT SA multilayer films are successfully formed based on the coordination interaction between ruthenium ions and terpyridine groups, and (2) a progressive assembly occurred regularly with almost an equal amount of deposition in each cycle. The SEM image showed a highly covered Ru(III)-tpy-MWCNT film on the substrate. Moreover, the optoelectronic conversion was also studied by assembling Ru(III)-tpy-MWCNT multilayer films on ITO substrates. Under illumination, the LBL SA films on ITO showed an effective photoinduced charge transfer because of their conjugated structure and the ITO current density changed with the number of bilayers. As the number of bilayer increases, the photocurrent intensity increases and reaches its maximum (∼65 nA/cm2) at six bilayers. These results allow us to design novel materials for applications in optoelectronic devices by using LBL SA techniques.

4-(2-(4-pyridinyl)ethynyl)benzenic diazonium salt (PBD) was synthesized and used to modify the substrate by self-assembly (SA) technique. Following decomposition of the diazonium group in PBD under UV irradiation, the ionic bonds between the diazonium salt and substrate are converted to covalent bonds. The PBD monolayer film anchored on substrates is very stable. Furthermore, the layer-by-layer (LBL) self-assembled films of bis(4,4'-bipyridine)(phthalocyaninato)ruthenium(II) (RuPc(bipy)2, BPR) and triruthenium dodecacarbonyl (Ru3(CO)12, TRDC) were fabricated on the PBD-modified substrates and characterized using UV-vis absorption spectroscopy, atomic force microscopy (AFM), and electrochemistry. The UV-vis analysis results indicate that the LBL TRDC-BPR self-assembled multilayer films with axial ligands between ruthenium atoms and pyridine groups were successfully fabricated and the progressive assembly runs regularly with almost equal amounts of deposition in each cycle. The AFM images of the seven-bilayer TRDC-BPR film on silicon wafer showed round-shaped small domains with sizes of 30-40 nm. The values of the energy band gap (Eg), the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) of six-bilayer TRDC-BPR on indium-tin-oxide (ITO) glass slides were measured using the UV-vis absorption spectrum and a cyclic voltammogram with values of 1.8, -5.0, and -3.2 eV, respectively. Under illumination, the self-assembled film on ITO showed effective photoinduced charge transfer and changed the current density. As the number of bilayers was increased, the photocurrent increased and reached its maximum value (approximately 150 nA/cm2) at six bilayers. A further increase in the number of bilayers led to a decrease in current due to the increase in cell resistance. The results allow us to design new materials with higher performance for optoelectronic applications.

A novel addition-curable novolac resin with phthalonitrile groups (PN) was successfully synthesized by a simple nucleophilic substitution reaction between the novolac resin and 4-nitrophthalonitrile. The final product was characterized with gel permeation chromatography (GPC), Fourier transform infrared (FT-IR) spectrometry, and proton nuclear magnetic resonance ( 1 H-NMR) spectroscopy. Processing capability and cure behavior of PN resin was investigated by rheometer and differential scanning calorimetry (DSC), respectively. Rheometric studies showed PN resin possessed a broad processing window between 140 and 225 C with a low viscosity from 0.4 to 4 Pa.s. DSC results showed PN resin can be cured at about 220 C via thermal polymerization of phthalonitrile groups. An ultrahigh curing temperature (such as 375 C) that was typical for the other phthalonitrile functional prepolymers was not necessary for this resin and 250 C was used as a maximum post-cure temperature to achieve the desired properties. Thermogravimetric analysis (TGA) showed T 5% (temperature of 5% weight loss) of the final cured products in nitrogen was 448.7 C, and the char yield was 70.29% at 900 C. Furthermore, T 5% of cured PN resin in air was 455.2 C, and the char yield in air was 34.48% at 700 C,revealing that the cured resin possessed excellent thermo-oxidative stability. Dynamic mechanical analysis (DMA) showed the inflection point of tan d was 371.9 C. The excellent processability and thermal stabilities proved PN resin as a promising candidate for advanced composite matrices.

4-(2-(4-pyridinyl)Ethynyl)benzenic diazonium salt (PBD) was used to modify multiwalled carbon nanotubes (MWCNTs) by the self-assembly technique. After the decomposition of the diazonium group in PBD under UV irradiation, the PBD monolayer film covalently anchored on multiwalled carbon nanotubes is very stable. The obtained pyridine-modified MWCNTs (Py(Ar)-MWCNTs) have good solubility in common organic solvents. Furthermore, the layer-by-layer (LBL) self-assembled fully conjugated films of Py(Ar)-MWCNTs and (phthalocyaninato)ruthenium(II) (RuPc) were fabricated on the PBD-modified substrates, and characterized using UV-vis absorption spectroscopy, scanning electron microscopy (SEM), and electrochemistry. The UV-vis analysis results indicate that the LBL RuPc/Py(Ar)-MWCNTs self-assembled multilayer films with axial ligands between the ruthenium atom and pyridine group were successfully fabricated, and the progressive assembly runs regularly with almost equal amounts of deposition in each cycle. A top view SEM image shows a random and homogeneous distribution of Py(Ar)-MWCNTs over the PBD-modified silicon substrate, which indicates well independence between all Py(Ar)-MWCNTs. Moreover, the opto-electronic conversion was also studied by assembling RuPc/Py(Ar)-MWCNTs multilayer films on PBD-modified ITO substrate. Under illumination, the LBL self-assembled films on ITO showed an effective photoinduced charge transfer because of their conjugated structure and the ITO current density changed with the number of bilayer. As the number of bilayers was increased, the photocurrent increases and reaches its maximum value (∼300 nA/cm(2)) at nine bilayers. These results allow us to design novel materials for applications in optoelectronic devices by using LBL self-assembly techniques.

A novel bifunctional comonomer 2-methylenesuccinamic acid (MLA) was synthesized to prepare poly(acrylonitrile-co-2-methylenesuccinamic acid) [P(AN-co-MLA)] copolymers, which can improve the stabilization of polyacrylonitrile significantly as a carbon fiber precursor. The structure and stabilization of P(AN-co-MLA) copolymers with different monomer feed ratios of AN/MLA were characterized by elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Reactivity ratio studies shows that MLA possesses higher reactivity than AN, resulting in higher MLA content in P(AN-co-MLA) copolymers than in the feed. The molecular weight and conversion of copolymer decrease gradually with the increase of MLA content in the feed. Comparing with PAN homopolymer, P(AN-co-MLA) copolymer has two or even three exothermic peaks, and the initial temperature of P(AN-co-MLA) copolymer is ca. 70 C lower than that of PAN, which broadens the exothermic peak. The DH/DT reduces from 34.01 J g À1 C À1 to less than 17.67 J g À1 C À1, confirming that the incorporation of MLA can avoid centralized heat release effectively.In addition, the extent of stabilization increases as the MLA content in P(AN-co-MLA) copolymer increases under the same heat treatment conditions. The activation energy (E a ) calculation shows cyclization E a of P(AN-co-MLA) reduces from ca. 168 kJ mol À1 to ca. 110 kJ mol À1, it is concluded that synthesized comonomer MLA can significantly improve stabilization of PAN, which is conducive to the preparation of high performance carbon fiber.

Nickel(II) Oxalate Dihydrate / Thermal Decomposition / Temperature Programmed-XRD / TGA-FTIRThe non-isothermal decomposition of NiC 2 O 4 · 2H 2 O was investigated under a dynamic inert atmosphere using a temperature-programmed X-ray diffractometer (TP-XRD) and a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrometer (TGA-FTIR). Both solid and gaseous products were analyzed in situ. The XRD pattern of the dehydration product did not match data for NiC 2 O 4 reported in the JCPDS file. The thermal decomposition of the dehydration product (NiC 2 O 4 ) took place in two sub-steps, both of which involved CO 2 evolution. Metallic nickel was the final product.

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