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Guest host systems composed of various types of esters of (2‐hydroxypropyl) cellulose and the chromophore coumarin 334 were characterized with respect to the absorption and emission properties as a function of the concentration of the chromophore and the nature of the esters. The results were compared with the ones obtained for solutions of the chromophore with low molar mass solvents. The cellulose derivatives are characterized by good film forming capabilities, a high solubility for the chromophores, by significant solvatochromic effects both in absorption and emission and by the formation of excimers at elevated concentration of the chromophores. These features make such cellulose derivatives interesting candidates as matrix materials for host‐guest systems in areas such as organic light emitting devices or sensors. Their tendency to display a cholesteric superstructure is of particular interest.

Butyric esters of (2‐hydroxypropyl) cellulose (BuPC) with different degree of substitution (DS) were synthesized via control of the esterification time of butyryl chloride and (2‐hydroxypropyl) cellulose. These BuPCs are thermotropic and displayed different colors at ambient temperature due to the formation of a cholesteric structure and the occurrence of a corresponding cholesteric reflection. The pitch height was found to increase significantly with a decrease of the degree of substitution. Both the glass transition temperature and the melting temperature are not affected by variation of the DS. The BuPC samples displayed a banded texture or focal‐conic texture, respectively. The X‐ray diffraction studies revealed the presence of a layer structure. The d‐spacing between two adjacent layers in the cholesteric structure displayed no significant dependence on the DS in the range from 2 to 3.

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Butyric esters (BuPC) of hydroxypropylcellulose (HPC) with different degrees of substitution (DS) were obtained by the reaction of (2‐hydroxypropyl)cellulose with butyryl chloride. Blends of these BuPCs were obtained from ternary solutions by removal of the common solvent. The blends displayed thermotropic cholesteric mesophases and showed iridescent colors at ambient temperatures depending on the blend composition. The spectroscopic analysis of the blends showed systematic variations of the reflection colors with variations of the ratio of the blend components between the reflection colors of the pure blend components covering the range from 453–938 nm corresponding to pitch heights from 308–640 nm.