Characterization and chain stiffness of (acetoxypropyl)cellulose

Abstract

A thermotropic cholesteric polymer, (acetoxypropyl)cellulose (APC), is prepared from (hydroxypropyl)cellulose and acetic anhydride. The unit ether and unit ester contents per anhydroglucose unit, determined by chromic acid oxidation and saponification, are 3.1 ± 0.3 and 1.9 • 0.1, respectively. Fractions ranging in molar mass from 2.2 X 104 to 6.5 X 105 daltons, and of the same chemical composition as the unfractionated polymer, are obtained by fractional precipitation with re-heptane. The limiting viscosity numbers of APC and fractions are measured in dimethyl phthalate at 25, 105, and 150 °C. The exponent in the Mark-Houwink-Sakurada relationship decreases from 0.88 ± 0.05 at 25 °C to 0.57 ± 0.05 at 150 °C, reflecting the gradually increasing flexibility of the molecular chain. The chain conformation parameters (equivalent Kuhn segment length, diameter, and mass per unit length) are calculated from the viscosity data by means

Playing the blues, the greens and the reds with cellulose-based structural colours

“…In addition to these factors it was also reported in the literature the inversion of chirality of the cholesteric phase for cellulose derivatives, which occurs not only for thermotropic 24 but also for lyotropic systems 23 . The tri-o-(𝛽-methoxyethoxy)ethyl cellulose, with a degree of polymerization (DP $$$$ ) of 11, was the first reported thermotropic cellulose derivative, which presented chirality inversion with temperature 24 .…”

“…Actually, the structural colours present in cellulosics are due to cholesteric phases that are obtained from lyotropic and/or thermotropic systems that were much studied in the eighties [12][13][14][15][16][17][18] . After the preliminary studies many other works were performed in order to obtain different coloured thermotropic cellulose derivatives, at room temperature, and to better understand the formation of right-and left-handedness in cellulose-based helicoidal liquid crystalline phases [19][20][21][22][23][24][25][26] . The photonic characteristics of the thermotropic, as well as lyotropic cellulosic systems, were found to depend on temperature, pressure, concentration, type of solvent and cellulose derivative.…”

“…The photonic characteristics of the thermotropic, as well as lyotropic cellulosic systems, were found to depend on temperature, pressure, concentration, type of solvent and cellulose derivative. The substituent, the average number of cellulose hydroxyl groups substituted per anhydro glucose unit, degree of substitution (DS $$$$ ), and the average molecular weight of the cellulose derivative were found to be crucial factors that influence not only the value of the cholesteric pitch but also the handedness of the helical structure 23,24 . One of the first thermotropic cellulose derivatives to be synthesized was acetoxypropylcellulose (APC), which exhibits liquid crystalline behaviour at room temperature.…”

Tunable topographical cellulose matrices for electro-optical liquid crystal cells

“…The pitch of the cholesteric helix can also be locked by using different procedures among them by photoinitiated crosslinking of pendant acrylate groups [10]. One of the most studied thermotropic cellulose esters is acetoxypropylcellulose (APC), it is cholesteric from below room temperature up to 180°C [6] and can originate lyotropic phases in some common solvents [11,12]. Rheo-optical and rheological studies [13] were also performed in APC in order to better understand the relationship between the textures observed in optical microscopy and the light scattering patterns.…”

Surface tailoring and design-driven prototyping of fabrics with 3D-printing: An all-cellulose approach

“…Cellulose acetate, which is commercially available and widely used, and acetoxypropyl cellulose (APC), which was synthetized from hydroxypropyl cellulose (HPC) by acetylation. APC has been previously studied mainly due to its ability to form cholesteric liquid crystalline solutions [22,23]. CA and APC materials are chemically similar as both are acetylated, but due to the more branched structure of APC, a difference in material and adhesion properties was expected.…”