title: Response surface methodology applied to the study of the microwave-assisted synthesis of quaternized chitosan.
abstract: A quaternized derivative of chitosan, namely N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride (QCh), was synthesized by reacting glycidyltrimethylammonium chloride (GTMAC) and chitosan (Ch) in acid medium under microwave irradiation. Full-factorial 2(3) central composite design and response surface methodology (RSM) were applied to evaluate the effects of molar ratio GTMAC/Ch, reaction time and temperature on the reaction yield, average degree of quaternization (DQ) and intrinsic viscosity ([η]) of QCh. The molar ratio GTMAC/Ch was the most important factor affecting the response variables and RSM results showed that highly substituted QCh (DQ = 71.1%) was produced at high yield (164%) when the reaction was carried out for 30min. at 85°C by using molar ratio GTMAC/Ch 6/1. Results showed that microwave-assisted synthesis is much faster (≤30min.) as compared to conventional reaction procedures (>4h) carried out in similar conditions except for the use of microwave irradiation.
authors.affiliation: Instituto de Química de São Carlos/Universidade de São Paulo, Av. Trabalhador são-carlense, 400-13566-590, São Carlos/SP, Brazil. Electronic address: danilomartins_1@hotmail.com.
authors.forename: Danilo Martins
authors.initials: DM
authors.lastname: dos Santos
authors.affiliation: Instituto de Química de São Carlos/Universidade de São Paulo, Av. Trabalhador são-carlense, 400-13566-590, São Carlos/SP, Brazil. Electronic address: andrea_bukzem@hotmail.com.
authors.forename: Andrea de Lacerda
authors.initials: Ade L
authors.lastname: Bukzem
authors.affiliation: Instituto de Química de São Carlos/Universidade de São Paulo, Av. Trabalhador são-carlense, 400-13566-590, São Carlos/SP, Brazil. Electronic address: scampana@iqsc.usp.br.
authors.forename: Sérgio Paulo
authors.initials: SP
authors.lastname: Campana-Filho
mesh_terms: D048271:Chitosan / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D004852:Epoxy Compounds / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008872:Microwaves; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D014783:Viscosity; D014961:X-Ray Diffraction
chemical_list: D004852:Epoxy Compounds; D000644:Quaternary Ammonium Compounds; C495830:chitosan-N-2-hydroxypropyl trimethyl ammonium chloride; C045006:glycidyl trimethylammonium; D048271:Chitosan
keywords: Chitosan derivatives; Microwave irradiation; Quaternization; Response surface methodology