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In this article, a new treatment method based on molecular self-assembly on carbon fiber (CF) surface was proposed for obtaining a controlled interface between CF and epoxy matrix in composite system. To form the controlled interfacial region, the surfaces of CF were first metallized by electroless Ag plating, then were reacted with a series of thiols (alkanethiols, aromatic thiol, and heterocyclic thiol) to form self-assembly (SA) films, which further reacted with epoxy resin to generate a strong adhesion interface. The structure and composition of untreated and treated CF surface were investigated by surface-enhanced Raman scattering spectroscopy (SERS) and X-ray photoelectron spectroscopy (XPS), respectively. SERS study showed that thiols chemisorbed on Ag-plated CF in the form of thiolate species via the strong SAg coordinative bond. Moreover, adsorbate orientation of thiols SA films on Ag-plated CF surfaces was revealed on the basis of SERS selection rules. The XPS study further confirmed the well organized alignment and the chemisorption of thiols. To understand the interfacial adhesion mechanism, the interfacial shear strength of CF/epoxy microcomposites was evaluated by the microbond technique. The results showed that among the parameters such as chain lengths, molecular orientation, and types of functional groups, the chemical nature of functional groups is most important for the improvement of interfacial properties in CF/epoxy composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A model compound was obtained by reaction of benzoic acid and 4,6-diamino-1,3-dihydroxybenzene dihydrochloride (DADHB · 2HCl) in the presence of functionalized multiwall carbon nanotubes (FMWNTs). FMWNTs were formed on raw multiwall carbon nanotubes (MWNTs) by chemical modification. The model compound was rinsed by chloroform and MWNTs were separated by centrifuge. The sediment yielded was denoted as graft multiwall carbon nanotubes (GMWNTs). Then X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier-transform infrared (FTIR) were used to investigate the existence of covalent bond between DADHB and FMWNTs. The results of XPS showed that nitrogen atoms amounted to about 3.3% except for oxygen and carbon on the surface of GMWNTs. Meantime, the reaction of COOH of the FMWNTs and themonomer DADHB occurred, and benzoxazole was formed predominantly by Raman spectroscopy analysis. FTIR spectroscopy confirmed the covalent grafting of monomer to FMWNTs in the processing procedure. As a result, the mechanism of the reaction of the poly(p-phenylenebenzoxazole) (PBO) oligomer and FMWNT composites was deduced according to the reaction of the model compound. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Raw multiwall carbon nanotubes (MWNTs) were first treated with strongly oxidated acid to form MWNTs–COOH and driven to a high dispersion quality in the dispersing medium via ultrasonic method. Then the MWNTs/poly (p-phenylene benzobisoxazole)(MWNTs–COOH/PBO) nanocomposites were prepared by an in situ polymerization technique. In this process, the morphological structure of MWNTs and MWNTs–COOH were investigated by XPS, FTIR, and TEM. The experimental results showed that the carboxyl group was introduced into the surface of nanotubes and the length of nanotubes was shortened. The images of SEM and AFM illustrated that the MWNTs–COOH was homogeneously dispersed in PBO matrix, and the DTA analysis indicated that the molecular weight of MWNTs–COOH/PBO was almost equal to that of PBO. Furthermore, the thermogravimetry results proved that the thermal property of MWNTs–COOH/PBO was more stable than that of PBO. Also, the knot strength and the tensile strength of MWNTs–COOH/PBO were 30% higher than that of PBO. In addition, the reaction route of the MWNTs–COOH and PBO oligomer was given according to the ATR–FTIR spectra of PBO polymer and MWNTs–COOH/PBO. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2500–2508, 2006