Role of hydrogen bonds in controlling the morphology of self-assembling carbamate systems.

With a view to understand the role of hydrogen bonding in controlling the morphology of self-assembling carbamate systems, N-octadecylcarbamate dodecyl ester was blended individually with a low molecular weight polyethylene and two commercial clarifiers, namely Kemamide S and Kemamide E 180. The effect of blending on the morphology of this long chain carbamate was investigated using optical microscopy, differential scanning calorimetry, and X-ray diffraction. The crystal structure of the carbamate was not affected by the addition of polyethylene or Kemamide S. The heterogeneous nucleation of the carbamate by the polyethylene or Kemamide S resulted in the reduction of the spherulite size of the carbamate, but it did not improve the transparency of the sample due to phase separation. On the other hand, significant improvement of transparency was achieved when the carbamate was blended with Kemamide E 180. Blending reduced the crystallite and spherulite size, heat of fusion, and crystallinity. An exchange of hydrogen bonds between the carbamate and Kemamide E is indicated in the IR spectra, and this affects the packing of the alkyl chains of the carbamates. This heterogeneous blending shows similar effects on the morphology as was achieved by blending two homologous carbamates in our previous study (J. Phys. Chem. B 2003, 107, 8416).