The sidewalls of multiwalled carbon nanotubes (MWCNTs) were decorated with CdS nanoparticles using a mild two-step approach, with in situ polymerized thiophene (PTh) acting as an interlinker. Extensive characterization of the materials has been carried out using transmission electron microscopy, selected area electron diffraction, X-ray diffraction, thermal gravimetric analysis, ultraviolet-visible absorption spectroscopy and photoluminescence spectroscopy. Optical limiting (OL) studies have been performed using the open Z-scan technique at the laser wavelengths of 532 and 1064 nm. The MWCNT-PTh-CdS system shows an enhanced OL effect in comparison to the pristine MWCNTs, particularly at 1064nm. Possible underlying mechanisms are proposed based on the results of nonlinear scattering measurements.

We report the synthesis and characterization of multiwalled carbon nanotube (MWCNT)– organically modified silicate (ORMOSIL) nanohybrid gel glass, in which the incorporated MWCNTs are covalently bonded to the silica network. The structural properties of the 3-aminopropyltriethoxysilane functionalized MWCNTs and MWCNT–ORMOSIL nanohybrid gel glass are comprehensively characterized using spectroscopic and electron microscopy techniques. We find that the agglomeration of incorporated MWCNTs is effectively restrained and that the MWCNTs are dispersed homogeneously and individually in the gel glass matrix. Compared with the mother MWCNT suspension, the resultant nanohybrid gel glasses demonstrate sustained nonlinear optical properties at both 532 and 1064 nm laser wavelengths.

The fabrication of nanocomposites by covalent inclusion of inorganic nanoparticles in an organic polymer matrix is highly topical and may find applications in the electronics, optics and energy sectors. Incorporation of CdS nanoparticles into the polyacrylonitrile (PAN) matrices could be expected to display improved or enhanced optoelectronic and optical properties. Using a newly synthesized RAFT agent, i.e., CdS-DDAT nanoparticles (DDAT: S-1-Dodecyl-S0-(a, a0-dimethyl-a00-acetic acid) trithiocarbonate), CdS covalently functionalized polyacrylonitrile (CdS-PAN) nanocomposite material was prepared in the presence of small amount of AIBN under ultrasonic radiation. This material, which exhibits an induced positive nonlinear absorption of incident light, has been well-characterized by a variety of physical techniques such as GPC, UV/vis, FT-IR, TGA, XRD and Z-scan.

Multi-walled carbon nanotubes (MWNTs) doped silica gel glass matrix nano-composites were successfully prepared by sol-gel technique. Morphology of the composites was characterized by scanning electrical microscope and transmittance electrical microscope images. Pore structure of net MWNTs, silica gel glass matrix and resulted MWNTs doped composites were studied and compared. The results show that MWNTs are well dispersed in the gel glass matrix and sol-gel processing does not appear to affect the morphology of MWNTs. Pore structure of the silica matrix is changed by the introduction of MWNTs.

A series of dimethyl-modified silica xerogels with different dimethyl contents were prepared by one-step hydrolysis and co-condensation from tetraethyloxysilane (TEOS) and dimethyldiethoxysilane (DEOS) containing precursor. The structural and textural evolution was traced by FT-IR spectroscopy, nitrogen absorption, scanning electron microscopy (SEM), transmittance electrical microscope (TEM), UV-Vis spectroscopy and thermogravimetric analysis (TGA). The addition of dimethyl groups can greatly reduce the pore size distribution of the resulted sample, while the 30% DEOS–70% TEOS sample is the most textural compact and therefore the most optical transparent. FT-IR and TGA results show that the samples are less hydroxygen containing owing to the hydrophobicity of the dimethyl groups.

Three kinds of ORMOSIL were obtained by one-step hydrolysis and co-condensation of tetraethyloxysilane (TEOS), together with methyltriethoxysilane (MTES), vinyltriethoxysilane (VTES), and c-glycidoxypropyltrimethoxysilane (GPTMS), respectively. IR spectra demonstrate the successful modification of silica network by methyl, vinyl, and c-glycidoxypropyl groups. The samples are mainly composed of amorphous silica phase without any detectable phase separation. The introduction of unhydrolysable organic groups retards the sol-gel process of the organoalkoxysilane and act as fillers in the silica network, leading to the condensation of the resulted ORMOSIL. Refractive index, hardness, and modulus are therefore increased.

This letter reports the effect of CNT doping levels on the pore structure of carbon nanotube (CNT)/silica xerogel composites, which would greatly influence the composite's physical behaviors and their applications in the field of optics. The composites were prepared by sol-gel technique and carried out pore structure analysis. The results show that there are mainly two grades of pores, centering at 8 and 15nm respectively, that existed in the structure. The relative ratio of the two-grade pores, also BET surface area and pore volume of the composites, change with the different CNT doping levels. The reason may be that the addition of CNTs can act as inhomogeneous crystalline sources, seduce the silica xerogel network to grow around them and therefore change the gel formation process of silica granules.

A multi-walled carbon nanotube (MWNT)/silica xerogel composite was prepared by sol–gel technique and characterized by Raman spectroscopy and transmission electron microscopy. The nonlinear optical property of MWNTs in liquid suspension and solid state matrix were investigated separately by open aperture Z-scan method, using 532 and 1064nm nanosecond laser pulses. The results show that both MWNT composite and suspension are nonlinear efficient at 1064 and 532nm, while MWNT composite may be more suitable for practical use because of their better nonlinear effect and possibly nondestructive nonlinear absorption mechanism.

We report here the study of the optical limiting mechanism of phthalocyanine(H2Pc) and different kinds of metallo-phthalocyanine(MPc) in silica gel glass matrix. Prepared by sol-gel technique, the H2Pc or MPc doped silica gel glass composites were transparent and homogeneous with the required regular shape. The optical limiting behaviors of the composites were measured at 532 nm with 8 ns pulses. The results show that among three samples of H2Pc, NiPc or PbPc doped composites, PbPc has the most obviously optical limiting effect owing to the heavy atom effect. Besides, PbPc has better optical limiting properties in solid-state silica gel glass matrix than in liquid-state DMF solution. Fluorescent ZnTSPc or GaPcCl doped composites have little optical limiting effect. The reasons are discussed from the view of excited physical process and the implied mechanism is given.

We report here the study of different peripherally modified palladium phthalocyanine (PdPc) encapsulated in silica gel glass obtained by solgel technique. The resulted composites were transparent and homogeneous with required optical limiting properties. Trapping effect was checked by UV/Vis absorption spectra and pore structure of the composites. Optical limiting properties were measured at 532 nm with 8 ns pulses. The results show that all the PdPcs have better optical limiting effect in composite than in solution, among which, PdPc-C has the best optical limiting effect due to its largest peripheral substituent.