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Some harmful volatile organic compounds (VOCs), such as formaldehyde, are regulated atmospheric pollutants. Therefore, development of a material to remove these VOCs is required. We focused on hydroxyapatite, which had been biomimetically coated on a polyamide film, as an adsorbent and found that formaldehyde was successfully removed by this adsorbent. The amount of formaldehyde adsorbed increased with the area of the polyamide film occupied by hydroxyapatite. The amount of adsorbed formaldehyde and its rate of adsorption were larger for hydroxyapatite deposited on polyamide film than for the commercially available calcined hydroxyapatite powder. This high adsorption ability is achieved by the use of nanosized particles of hydroxyapatite with low crystallinity and containing a large number of active surface sites. Therefore, hydroxyapatite biomimetically coated on organic substrates can become a candidate material for removing harmful VOCs such as formaldehyde.

Modification of organic polymer with silanol groups in combination with calcium salts enables the polymer to show bioactivity, that is, the polymer forms apatite on its surface after exposure to body environment. However, how modification with silanol groups influences ability of apatite formation on the polymer substrate and adhesive strength between polymer and apatite is not yet known. In the present study, polyamide containing carboxyl groups was modified with different amounts of silanol groups, and its apatite-forming ability in 1.5SBF, which contained ion concentrations 1.5 times those of simulated body fluid (SBF), was examined. The rate of apatite formation increased with increasing content of silanol groups in the polyamide films. This may be attributed to enhancement of dipole interactions. A tendency for the adhesive strength of the apatite layer on the polyamide film to be decreased with increasing content of silanol groups was observed. This may be attributed to swelling in 1.5SBF and having a high degree of shrinkage after drying. These findings clearly show that modification of organic polymers with the functional groups induces apatite deposition, and also determines the adhesive strength of the apatite layer to the organic substrates.

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The influence of phosphoric acid on the activity of Sb(III) catalyst was studied in the catalytic polycondensation of bis(2-hydroxyethyl) terephthalate (BHET). Although the rate of polycondensation in the initial stage was depressed by the addition of phosphoric acid to the Sb(III) catalyst, subsequent polycondensation was accelerated to give a higher-molecular-weight poly(ethylene terephthalate) as compared with that obtained in the absence of phosphoric acid. The yield of by-products in the polycondensation was also affected by the addition of phosphoric acid; the formation of acetaldehyde decreased, and that of the diethylene glycol unit increased. It was made clear from studies of 31 P NMR that the phosphoric acid was converted into phosphate (0= P(OC2H4 0R)3) in the early stage of the polycondensation by reaction with BHET or ethylene glycol which was generated in the polycondensation ofBHET. It is assumed that the modification of the polycondensation reaction caused by the addition of phosphoric acid is due to the complexation of Sb(III) catalyst with the phosphate. The mechanism for the polycondensation of BHET catalyzed by Sb(III) compounds in the presence of phosphoric acid was proposed on the basis of these findings. KEY WORDS Bis(2-hydroxyethyl) Terephthalate I Poly(ethylene !erephthalate) I Polycondensation I Sb(III) Catalyst I Phosphoric Acid I 31p NMR I

ABSTRACT:The copolymerization of iso-or terephthaloyl chloride, m-phenylenediamine or diaminodiphenylsulfone, and 3,5-diaminobenzoic acid or 2,4-diaminobenzene sulfonic acid (or sulfonate) was studied. Copolymers with high reduced viscosity could be obtained by low temperature solution polymerization, but not by interfacial polymerization. The reduced viscosity of the copolyamides obtained was dependent upon the species of the aromatic diamine compounds and the acid acceptors used. Low temperature solution copolymerization with the comonomer 3,5-diaminobenzoic acid should be done without acid acceptors, because acid acceptors cause gelation. With 2,4-diaminobenzenesulfonic acid or 2,4-diaminobenzenesulfonate, pyridine or triethylamine as acid acceptors give polymers with higher reduced viscosity. The flat asymmetric membranes of the copolyamides prepared from terephthaloyl dichloride and mixed diamine components of 3,3Ј-diaminodiphenylsulfone and 3,5-diaminobenzoic acid showed not only good reverse osmosis performance, but also high chlorine resistance.

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