No abstract

We report on the synthesis and self-assembly of a new series of twin-tapered dihydrazide derivatives, oxalyl acid N′, N′-di(3,4,5-trialkoxybenzoyl)-hydrazide (FH-Tn). Results from 1 H NMR diluting experiments in chloroform and temperature-dependent 1 H NMR spectroscopy revealed that molecules exhibited a conformational change at concentrations lower than 255 µM, e.g., from intramolecularly H-bonded sixmembered rings to five-membered rings in the monomer state upon concentrating. Measurements of 1 H NMR diluting experiment, FTIR spectroscopy, and mass spectroscopy revealed that the FH-Tn selfassembled into supramolecular chains either in chloroform at concentrations greater than 255 µM or in bulk through intermolecular quadruple H-bonding. On the basis of the results of DSC, polarized optical microscopy, and wide-angle X-ray diffraction (WAXD), we assigned enantiotropic hexagonal and unknown columnar phases to FH-Tn (n ) 6, 7, 8, 10).

No abstract

The crystallization behavior of poly(vinylidene fluoride)/ montmorillonite (PVDF/MMT) nanocomposite was investigated by using differential scanning calorimeter (DSC), polarizing optical microscope (POM), and X-ray diffraction. The results showed that the crystallization behavior of PVDF was changed by adding MMT in PVDF matrix. The MMT layers in PVDF acted as effective nucleation agents. It is observed that the crystallization temperature of PVDF/MMT nanocomposite was higher than that of PVDF at various cooling rates. The value of half-time of crystallization showed that the crystallization rate of PVDF/MMT nanocomposite was faster than that of PVDF at a given cooling rate. The addition of MMT hindered the growth of spherulite. Nonisothermal crystallization data was analyzed using Avrami, Ozawa, and Jeziorny method. The Jeziorny method successfully described the nonisothermal crystallization behaviors of PVDF/MMT nanocomposite. The MMT loading was favorable to produce the piezoelectric b phase in the PVDF matrix. The a phase coexisted with the b phase in the PVDF/MMT nanocomposite. For this polymorphic structure, a possible explanation was proposed based on the variable temperature X-ray diffraction, DSC, and POM experiments.

No abstract