title: Extensively deacetylated high molecular weight chitosan from the multistep ultrasound-assisted deacetylation of beta-chitin.
abstract: High intensity ultrasound irradiation was used to convert beta-chitin (BCHt) into chitosan (CHs). Typically, beta-chitin was suspended in 40% (w/w) aqueous sodium hydroxide at a ratio 1/10 (gmL(-1)) and then submitted to ultrasound-assisted deacetylation (USAD) during 50min at 60°C and a fixed irradiation surface intensity (52.6Wcm(-2)). Hydrogen nuclear magnetic resonance spectroscopy and capillary viscometry were used to determine the average degree of acetylation (DA‾) and viscosity average degree of polymerization (DPv‾), respectively, of the parent beta-chitin (DA‾=80.7%; DPv‾=6865) and USAD chitosans. A first USAD reaction resulted in chitosan CHs1 (DA‾=36.7%; DPv‾=5838). Chitosans CHs2 (DA‾=15.0%; DPv‾=5128) and CHs3 (DA‾=4.3%; DPv‾=4889) resulted after repeating the USAD procedure to CHs1 consecutively once and twice, respectively. Size-exclusion chromatography analyzes allowed the determination of the weight average molecular weight (Mw‾) and dispersity (Ð) of CHs1 (Mw‾=1,260,000gmol(-1); Ð=1.4), CHs2 (Mw‾=1,137,000gmol(-1); Ð=1.4) and CHs3 (Mw‾=912,000gmol(-1); Ð=1.3). Such results revealed that, thanks to the action of high intensity ultrasound irradiation, the USAD process allowed the preparation of unusually high molecular weight, randomly deacetylated chitosan, an important breakthrough to the development of new high grade chitosan-based materials displaying superior mechanical properties.
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo (IQSC/USP), Avenida Trabalhador são-carlense, 400 São Carlos, Brazil; Ingénierie des Matériaux Polymères (IMP), CNRS UMR 5223, Université Claude Bernard Lyon 1, Univ Lyon, Villeurbanne F-69622, France.
authors.forename: Anderson
authors.initials: A
authors.lastname: Fiamingo
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo (IQSC/USP), Avenida Trabalhador são-carlense, 400 São Carlos, Brazil; Ingénierie des Matériaux Polymères (IMP), CNRS UMR 5223, Université Claude Bernard Lyon 1, Univ Lyon, Villeurbanne F-69622, France.
authors.forename: Jorge Augusto de Moura
authors.initials: JAM
authors.lastname: Delezuk
authors.affiliation: Ingénierie des Matériaux Polymères (IMP), CNRS UMR 5223, Université Claude Bernard Lyon 1, Univ Lyon, Villeurbanne F-69622, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Trombotto
authors.affiliation: Ingénierie des Matériaux Polymères (IMP), CNRS UMR 5223, Université Claude Bernard Lyon 1, Univ Lyon, Villeurbanne F-69622, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: David
authors.affiliation: Instituto de Química de São Carlos, Universidade de São Paulo (IQSC/USP), Avenida Trabalhador são-carlense, 400 São Carlos, Brazil. Electronic address: scampana@iqsc.usp.br.
authors.forename: Sergio Paulo
authors.initials: SP
authors.lastname: Campana-Filho
mesh_terms: D000107:Acetylation; D002686:Chitin; D048271:Chitosan; D008970:Molecular Weight; D012972:Sodium Hydroxide; D014783:Viscosity
chemical_list: D002686:Chitin; D012972:Sodium Hydroxide; D048271:Chitosan
keywords: Beta-chitin; Chitosan; Deacetylation; High molecular weight; Ultrasound