Teiichi Tanigaki

Synthesis and thermal properties of polyesters from cyclotriphosphazene

Abstract Polyesters containing cyclotriphosphazene units have been prepared by phase transfer catalyzed two-phase polycondensation and direct polycondensation. The polycondensation of the acid chloride of ( trans -2,4-dicarboxyphenoxy-2,4,6,6-tetraphenoxy)cyclotriphosphazene ( trans -CPP) and bisphenol A (BA) in the presence of benzyltriethylammonium chloride (BTEAC) as phase transfer reagent gave a polyester with a molecular weight of 22,000, whereas only oligomer was obtained by the polycondensation of the cis -isomer with BA. The result indicates that the trans -isomer is favorable to effective growth of the polyester. The direct polycondensation using SOCl 2 /pyridine and TsCl/DMF, however, resulted in the formation of low molecular weight polyesters even though trans -CPP was used. In the copolycondensation of BA with acid chlorides of trans -CPP and terephthalic acid, copolymers with molecular weights of 24,000-13,000 were obtained. The homopolyester prepared from trans -CPP and BA exhibited a significantly low glass transition temperature of 65 °C, and the copolymers had glass transition temperatures in the range 220-91 °C, depending on the contents of trans -CPP units. Thermogravimetric analysis showed that the homopolyester was stable up to 390 °C in a nitrogen atmosphere, and the char yield of copolyester with 5.5 mol.% of trans -CPP unit was 36% at 600 °C, which was seven times higher than that of the polyester without cyclotriphosphazene units. The presence of cis -CPP units in the polyesters lowered the initial decomposition temperatures, but not char yields.

Polymerization of styrenes with pendant aminophosphazenes and fluorescence behaviors of their Eu3+ complexes

Abstract Radical polymerizations of novel styrenes with pendant penta(3-dimethylaminopropylamino)-(SPDAP) and penta(2-dimethyl aminoethoxy)cyclotriphosphazene (SEAP) in various solvents and the fluorescence behavior of complexes of Eu3+ with these cascade materials were studied. The conversion of SEAP increased on going from THF to ethanol, whereas the conversion of SPDAP in ethanol showed the lowest value. The application of the Kamlet-Taft equation to the conversion suggested that the polymerization of SPDAP and SEAP is primarily affected by the hydrogen bond interaction. 13C NMR spectra of SEAP showed that the peak of the β-carbon in the vinyl group shifted downfield as the conversion increased. This suggests that the interaction between the monomer and solvents brings about a change of polymerizability of SEAP. A similar downfield shift was observed for SPDAP in ethanol, suggesting that SPDAP also has a high polymerizability. The inherent viscosities of poly(SEAP) and poly(SPDAP) in ethanol were found to be considerably higher than those in THF. This result and the kinetic treatment of polymerization suggest that the side arms on the phosphazene ring in ethanol are expanded due to the hydrogen bond interactions with the solvent, and that the propagation is sterically hindered, especially for the polymerization of SPDAP with relatively long side arms. This might be responsible for the low conversion observed for the polymerization of SPDAP in ethanol. When Eu31 ions were added to SPDAP, a significant increase in fluorescence intensity of Eu3+ was observed. The plot of fluorescence intensity vs the concentration of SPDAP suggests the formation of a 2:1 SPDAP-Eu3+ complex. For the polymer-Eu3+ complex, a similar increment of the intensity was observed. From the chemical shifts of side arms in the monomer-Eu3+ complex, the structure of the complex is discussed.

Effects of coronands on ionic conductivities of complexes of poly[2-(4-vinylphenoxy)-2,4,4,6,6-penta(methoxyethoxyethoxyethoxy)cyclotriphosphazene] with LiClO4

The effects of coronands such as crown ether and azacrown on the conductivity of complexes of LiClO 4 with poly[2-(4-vinylphenoxy)-penta(methoxyethoxyethoxyethoxy)cyclotriphosphazene] [poly(STEP)] were investigated. The extent of T g elevation of poly(STEP)-LiClO 4 with 18-crown-6 was comparable to that of the poly(STEP)-LiClO 4 system. A similar behavior was observed for the system containing 12-crown-4. However, the increase in T g values is considerably suppressed when tetraazacyclotetradecane with methoxyethoxy group as a side arm (MTAC) is used. All of the additives are effective to improve the conductivity, and the maximum conductivities of 10 -4 S/cm at 30°C and 10 -3 S/cm at 90°C have been achieved for the complex of the poly(STEP)-LiClO 4 -MTAC system with Li + /O = 0.06, which are 3.5-7 times higher than those of poly(STEP)-LiClO 4 complexes. From the behaviors of T g elevation and the conductivity, the role of the coronands for the conduction of the multi-armed poly(STEP)-LiClO 4 system is discussed.

Ionic conductivities in polystyrene carrying a pendant oligo (oxyethylene)cyclotriphosphazene-alkali thiocyanate complexes

Abstract Ionic conductivities of complexes of poly(2-(4-vinyl-phenoxy)penta{[(methoxyethoxy)ethoxy]ethoxy}cyclotriphosphazene]) ((poly(STEP)) with alkali thiocyanates (K + , Na + and Cs + ) have been measured. The same glass transition temperature ( T g ) rise was observed for K + and Na + salt complexes, which was higher than that of Cs + salt complexes. The poly(STEP) complexes with these salts exhibit good ionic conductivities, especially for poly(STEP)-Cs + salt complexes, approaching 10 −4 S/cm at 30°C and 10 −3 S/cm at 90°C. The fast ion transport could be explained by the formation of a conducting phase consisting of a number of oxyethylene side chains attached to a cyclotriphosphazene. From the correlation between polymer characteristics and conductivities, the conduction appears to occur at a rate governed by the segmental mobility of side chains, cation-oxygen atom binding energy, and the structural factor for complex formation.