title: Chitosan cross-linking with a water-soluble, blocked diisocyanate. 1. Solid state.
abstract: The present investigation focuses on the synthesis and application of a cross-linking agent that is compatible with the solubility characteristics of chitosan. A water-soluble, blocked-diisocyanate was prepared as a bisulfite adduct to 1,6-hexamethylene diisocyanate, which proved to be stable for several weeks in aqueous, acidic chitosan solutions at room temperature. Thermal cross-linking of chitosan as cast, dried films was investigated by varying the NCO/NH(2) ratio from 0.0 to 1.2. Spectroscopic (IR), thermal (TGA), swelling, and structural (WAXD) studies indicated that chitosan was cross-linked in a concentration-dependent manner under mild thermal conditions: 60 degrees C for 24 h. Cross-linking inefficiency was concluded to be due to lack of mobility of the reacting species in the solid state. In a preliminary study, the enzymatic degradation with Chitinase (E. C. 3.2.1.14) from Streptomyces griseus was found to be the greatest for non-crosslinked chitosan, followed by chitin, and then by cross-linked samples.
authors.affiliation: Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, D.C. 20375, USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Welsh
authors.forename: Caroline L
authors.initials: CL
authors.lastname: Schauer
authors.forename: Syed B
authors.initials: SB
authors.lastname: Qadri
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Price
mesh_terms: D001673:Biodegradation, Environmental; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry*; D002688:Chitinases / Q000378:metabolism; D048271:Chitosan; D003432:Cross-Linking Reagents / Q000737:chemistry*; D003485:Cyanates / Q000737:chemistry; D017953:Isocyanates / Q000737:chemistry*; D012995:Solubility; D013696:Temperature
chemical_list: D003432:Cross-Linking Reagents; D003485:Cyanates; D017953:Isocyanates; C015262:1,6-hexamethylene diisocyanate; D002686:Chitin; D048271:Chitosan; D002688:Chitinases