Preparation and liquid-crystalline properties of toluene-4-sulphonyl urethane of hydroxypropylcellulose |
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| Authors: | M. H. Godinho J. P. Borges J. C. Bordado M. T. Cidade A. F. Martins |
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| Affiliation: | 1. Universidade Nova de Lisboa, Faculdade de Ciěncias e Tecnologia , Monte da Caparica, 2825 , Monte da Caparica , Portugal;2. Centre de Física da Matéria Condensada , Av. Prof. Gama Pinto, 2, 1699 , Lisboa Codex , Portugal |
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| Abstract: | Abstract A novel liquid-crystalline polymer, the toluene-4-sulphonyl urethane of hydroxypropylcellulose (TSUHPC), was prepared through chemical modification of hydroxypropylcellulose (HPC) of Mw = 60000 g mol?1. The resulting polymer was characterized by infrared spectroscopy, differential scanning calorimetry (DSC) and polarizing microscopy. It was found that thermotropic liquid crystal phases are formed between about 60°C and 110°C. Concentrated solutions of TSUHPC in acetone and N,N-dimethylacetamide exhibit cholesteric behaviour, at room temperature. When approaching the lyotropic mesophase to solid transition, either by cooling or by solvent evaporation, very interesting arborescent structures of a seemingly fractal nature may be observed, depending on the kinetics of the transition. A banded texture can be observed when the polymer is sheared near the transition to the isotropic phase. |
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