Mesomorphic organisation of (2-hydroxypropyl)cellulose under the influence of silica networks

Mesomorphic behaviour of (2-hydroxypropyl)cellulose (HPC) within organic-inorganic hybrid materials was investigated. Hybrid materials HPC/silica were prepared by means of the sol-gel process, with hydrolysis and condensation of (tetraethoxy)silane taking place in the mesomorphic environment of HPC. Solid films of HPC/silica were investigated using the Raman spectroscopy, differential scanning calorimetry, thermo-optical analysis, and small angle X-ray scattering. Additionally, swelling by water was tested. The analysis of the results leads to the following conclusions: (i) silica has a strong stabilisation effect on the mesomorphic organisation of HPC: the glass transition temperature and isotropisation temperature of HPC are shifted to higher values; (ii) X-ray measurements reveal a nano-scale organisation of the HPC/silica hybrids with d-spacing equal to 65A; a long-range organisation within HPC/silica hybrids seems to be related to a surface induced ordering; (iii) curing of HPC/silica hybrids affects the swelling behaviour. s.