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Nanocomposites of poly(lactide) (PLA) and the PLA plasticized with diglycerine tetraacetate (PL-710) and ethylene glycol oligomer containing organo-modified montmorillonites (ODA-M and PGS-M) by the protonated ammonium cations of octadecylamine and poly(ethylene glycol) stearylamine were prepared by melt intercalation method. In the X-ray diffraction analysis, the PLA/ODA-M and plasticized PLA/ODA-M composites showed a clear enlargement of the difference of interlayer spacing between the composite and clay itself, indicating the formation of intercalated nanocomposite. However, a little enlargement of the interlayer spacing was observed for the PLA/PGS-M and plasticized PLA/PGS-M composites. From morphological studies using transmission electron microscopy, a finer dispersion of clay was observed for PLA/ODA-M composite than PLA/PGS-M composite and all the composites using the plasticized PLA. The PLA and PLA/PL-710 composites containing ODA-M showed a higher tensile strength and modulus than the corresponding composites with PGS-M. The PLA/PL-710 (10 wt %) composite containing ODA-M showed considerably higher elongation at break than the pristine plasticized PLA, and had a comparable tensile modulus to pure PLA. The glass transition temperature (T g ) of the composites decreased with increasing plasticizer. The addition of the clays did not cause a significant increase of T g .

A new crown ether spin-labeled by the phenoxyl radical moiety was prepared. Intramolecular odd-π electron delocalization was investigated by means of ENDOR spectroscopy. On the basis of ENDOR spectrometric titration, the equilibrium constant for Na+-labeled crown-ether-complex formation was evaluated to be pKNa+=3.5 in 2-propanol at −30 °C.

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