Propanoate esters, cellulosics

Macroscopic and microscopic conformational changes of cellulose esters in CDC13 solution have been examined as a function of temperature and concentration.120 The temperature dependence of the T, values for the carbonyl and ring carbons of CTA in CDC13 shows a remarkable change in segmental motion at 53°C. This apparent transition, which is observed neither in solutions of CTA in (CD3)2SO nor in solutions of cellulose propanoate and cellulose butanoate in... 

Acetoxypropyl cellulose (APC) [74, 75] 2-Hydroxypropyl cellulose (HPC) [76] Trifluoroacetate ester of HPC [77] Propanoate ester of HPC [78] Benzoate ester of HPC [79] thin films... 

Synonyms CAP Cellulose, acetate propanoate Cellulose acetate propionate ester Cellulose acetopropionate Cellulose propionate CP Ciassification Thermoplastic... 

On the other hand, literature data show [16] that different cellulose derivatives which form liquid crystalline solutions in organic solvents may also form cholesteric thermotropic phases in the absence of a solvent—with spontaneous molecular orientation and cholesteric reflection, such as 2-acetoxypropyl cellulose, 2-hydroxypropyl cellulose, the trifluoroacetate ester of hydroxypropyl cellulose, the propanoate ester of hydroxypropyl cellulose, the benzoate ester of hydroxypropyl cellulose, 2-ethoxypropyl cellulose, acetoacetoxypropyl cellulose, trifluoroacetoxypropyl cellulose, the phenylac-etate and 3-phenylpropionate of hydroxypropyl cellulose, phenylacetoxy, 4-methoxy-phenylacetoxy, p-tolylacetoxy cellulose, trimethylsilyl cellulose, trialkyl cellulose, cellulose trialkanoate, the trialkyl ester of (tri-o-carboxymethyl) cellulose, 6-o-a-(l-methylnaphthalene)-2,3-o-pentyl cellulose, etc. Moreover, the suspensions of cellulose crystallites spontaneously form the chiral nematic phase. The formation of mesophase suspension of cellulose crystalHtes varies from one type of cellulose to another, being influenced, in the formation of the chiral nematic phase, by the mineral acid selected... 

Gray s group also prepared the propanoate of (2-hydroxypropyl)cellulose (PPC or C3PC) from the esterification reaction of HPC (Mw = 100,000 g/mol) and propionyl chloride or propionic anhydride in acetone (Tseng et al. 1982). The appearance and behavior of the polymer is similar to APC, however this ester displayed iridescent colors at room temperature. In the same year (Bhadani and Gray 1982), the synthesis of the benzoic acid ester of HPC (BzPC) from the reaction of the aromatic benzoyl chloride with HPC in pyridine was described. The polymer showed a thermotropic liquid crystalline phase below 160 °C. Benzoic acid ester of HPC was fractionated from acetone solution by precipitation with methanol-water and polymers with different molecular weights were obtained (Bhadani et al. 1983). 

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