title: Effect of the degree of substitution in the transition temperatures and hydrophobicity of hydroxypropyl cellulose esters.
abstract: We have synthesized and characterized five members of a homologous series of side chain polymers of hydroxypropyl cellulose esters obtained by homogeneous esterification with 6-[4'-(ethoxycarbonyl)biphenyl-4-yloxy]hexanoic acid. Two acylation procedures were studied. One procedure involved the acid chloride derivative and the other one was the activation of that acid with N,N'-carbonyldiimidazol. The second method yielded esters with higher degree of substitution, DS¯. The esters, with DS¯ ranging from 26 to about 66%, were characterized by FTIR, NMR, solution viscometry, TGA, DSC, polarized optical microscopy, and X-ray diffraction, in order to study the effect of the degree of substitution on the hydrophobicity, on the transition temperatures and on their potential liquid crystal properties. It has been found that the hydrophobicity and the transition temperatures of the HPC derivatives are very much dependent on the degree of acylation. The esters with high DS¯ values showed liquid crystal properties.
authors: Fac. de Ciencias Químicas, BUAP. Blvd. de la 14 Sur y Av. San Claudio, Cd. Universitaria (Antiguo edificio de la Fac. de C. Quím.), Col San Manuel, Puebla Pue., C.P. 72570. Mexico.
authors: Delia
authors: D
authors: López-Velázquez
authors: Fac. de Ciencias Químicas, BUAP. Blvd. de la 14 Sur y Av. San Claudio, Cd. Universitaria (Antiguo edificio de la Fac. de C. Quím.), Col San Manuel, Puebla Pue., C.P. 72570. Mexico.
authors: Armando R
authors: AR
authors: Hernández-Sosa
authors: Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC), Juan de la Cierva 3, 28006 Madrid, Spain. Electronic address: ernestop@ictp.csic.es.
authors: Ernesto
authors: E
authors: Pérez
mesh_terms: D000215:Acylation; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D050866:Liquid Crystals / Q000737:chemistry; D044366:Transition Temperature
chemical_list: D002482:Cellulose; C008079:hydroxypropylcellulose
keywords: Benzyl 6-bromohexanoate (PubChem CID: 562258); Homogeneous acylation; Hydrophobicity; Hydroxypropyl cellulose esters; Liquid crystals.; N,N′-Carbonyldiimidazole (PubChem CID: 68263); Tetramethylammonium fluoride trihydrate (PubChem CID: 2735143)