Morphology and thermal behavior of self-assembling carbamates

Hydrogen bond mediated self-assembling carbamates with alkyl side chains of different lengths were investigated with respect to thermal behavior and morphology. The length of the side chain has an influence on the heat of fusion, crystallinity, and crystallite size. Morphologies of samples slowly cooled from the melt and those quenched were different. While plasticizers or clarifiers are usually used to modify the crystalline morphology of materials, we examined the possibility of effecting similar changes by blending any two types of carbamates. Although both the heat of fusion and crystallinity decrease initially with the addition of the second component, they recover beyond a certain composition. The spherulite size also decreases significantly, enhancing the transparency of the sample. Thermal analysis shows that the components of the blend exercise a mutual plasticizer effect, reducing the melting temperatures. The changes in morphology upon blending are not due to a decrease in the extent of hydrogen bonding but can be attributed to the disorder in the packing of the alkyl side chains.