The solubilities of several organic compounds in dense carbon dioxide (both liquid and supercritical) have been determined. Our data supplements earlier work by Francis. Based on these two sets of data, the structural features that either limit or enhance the solubility of different groups of compounds are identified. By use of this approach, some general structure-carbon dioxide solubility relationships have been developed and are illustrated by examples in the case of hydrocarbons, alcohols, phenols, aldehydes, ethers, esters, amines, and nitro compounds. These relationships can be used in qualitative predictions about the solubilities of substances in carbon dioxide; such information would be useful in enhanced oil recovery operations, supercritical fluid chromatography, and supercritical fluid extraction.

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A new route to interfacial bonding between ceramic and matrix in biocomposites is identified. A tailored allyl phosphonic acid is used as a coupling agent bound to the surface of a bioceramic to form a 'grafted' calcium phosphate (CAP). The allyl phosphonic acid coupling agent is synthesised by reaction of allyl halide and trialkyl phosphite. Successful synthesis was confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopy (FTIR). The allyl phosphonic acid was incorporated onto calcium phosphate using a wet chemical coprecipitation synthesis route. The resulting 'grafted' CAP was characterised using FTIR coupled with photoacoustic sampling, and Fourier transform Raman spectroscopy (FTR). The spectroscopic data suggest an interaction between the allyl phosphonic acid and calcium phosphate resulting from observed reductions in intensity of the hydroxyl (3570 cm 21 ) and phosphate n 3 (1030 cm 21 ) peaks. The continued presence of C5C functionality on the surface of the grafted CAP was indicated by FTIR and FTR spectra (peaks at 1650 and 1635 cm 21 respectively) and confirmed by X-ray photoelectron spectroscopy (XPS). On the basis of these results, it is concluded that grafted CAP may be used to produce a chemically bonded composite with superior mechanical properties.