Thermotropic mesomorphism of (2-hydroxypropyl)cellulose systems-the role of hydrophilic and lipophilic segments

The (2-hydroxypropyl)cellulose (HPC) derivatives can be regarded as a syste m which is composed of poly(saccharide) main chain (hydrophilic segment) an d aliphatic side chain as a hydrophobic (lipophilic) segment of the macromo lecules. The influence of the hydrophobic effect on the thermotropic mesomo rphism of HPC derivatives was investigated. The correlation between d-spaci ng of HPC-derivatives estimated from X-ray measurements and hydrophobic eff ect of the side chain was found. The relative hydrophobicity variation of t he side chains of HPC-derivatives leads to an increase in the d-spacing bet ween poly(saccharide) main chains. On the other hand, the increasing d-spac ing in the HPC-derivatives shifts their transition temperatures to isotropi c state and glass transition temperatures towards lower temperature range. It was suggested that the property/structure correlation of the HPC-derivat ives is affected by the balance between hydrophilic and hydrophobic parts o f the HPC-derivative macromolecules.