Data/hora: 23/09/2024 16:15:33

Biblioteca(s): 	Embrapa Algodão.	
Data corrente: 	14/01/2020	
Data da última atualização: 	20/01/2020	
Autoria: 	VASCONCELOS, N. F.; FEITOSA, J. P. A.; ANDRADE, F. K.; MIRANDA, M. A. R.; SASAKI, J. M.; MORAIS, J. P. S.; SILVA, L. M. A. e; CANUTO, K. M.; ROSA, M. de F.	
Afiliação: 	Niédja Fittipaldi Vasconcelos, Universidade Federal do Ceará - UFC/Departamento de Química; Judith Pessoa Andrade Feitosa, Universidade Federal do Ceará - UFC/Departamento de Química; Fábia Karine Andrade, Universidade Federal do Ceará - UFC/Departamento de Engenharia Química; Marcus Aurélio Ribeiro Miranda, Universidade Federal do Ceará - UFC/Departamento de Física; José Marcos Sasaki, Universidade Federal do Ceará - UFC/Departamento de Física; JOAO PAULO SARAIVA MORAIS, CNPA; LORENA MARA ALEXANDRE E SILVA, CNPAT; KIRLEY MARQUES CANUTO, CNPAT; MORSYLEIDE DE FREITAS ROSA, CNPAT.	
Título: 	Chemically modified cellulose nanocrystals as polyanion for preparation of polyelectrolyte complex.	
Ano de publicação: 	2019	
Fonte/Imprenta: 	Cellulose, v. 26, n. 3, p. 1725-1746, February 2019.	
Idioma: 	Inglês	
Conteúdo: 	Bacterial cellulose nanocrystals (BCNCs) have hydrophilic surfaces due to hydroxyl groups but are water-insoluble. The carboxymethylation improves the solubility of cellulose in polar media through the insertion of carboxymethyl groups. This study aims to evaluate the use of two different alcoholic solvents in the carboxymethylation reaction of BCNCs: ethanol and isopropanol. BCNCs were obtained under two hydrolysis conditions: sulfuric acid (BCNC-S) and combination of sulfuric and hydrochloric acids (BCNC-S/Cl). Two techniques (NMR and titration) were used to determine the degree of substitution (DS) values. Carboxymethylation of BCNC-S/Cl led to high DS compared to BCNC-S and the use of isopropanol promoted an even greater DS. The thermal properties were not affected after the chemical modification. However, functionalization provided an increase in the negative charge density at the surface of nanostructures and a change in the crystal structure (cellulose type Ia for amorphous), making this material a potential polyanion for the synthesis of polyelectrolyte complexes (PECs). The micrographs showed that the nanocrystals became soluble after carboxymethylation. Carboxymethylated bacterial cellulose nanocrystals hydrolyzed through the mixture of inorganic acids and modified using isopropanol (CBCNC-S/Cl-IPA) was a suitable polyanion to produce PECs with chitosan. The PECs produced had particle size ranging from 276 to 588 nm and zeta potential ranging from - 24.3 to + 39.0 mV.	
Palavras-Chave: 	Carboxymethylation; Polyelectrolytic complexes.	
Thesaurus Nal: 	Chitosan; Hydrolysis; Nanocrystals.	
Categoria do assunto: 	--	
URL: 	http://ainfo.cnptia.embrapa.br/digital/bitstream/item/208702/1/Chemically-modified-cellulose.pdf	
Registro original: 	Embrapa Algodão (CNPA)	
Exemplares: 	CNPA - (28706-1) - UPC - AP - DD -  -  -  - DIS