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Acid hydrolysis of commercial chitosans
Author(s) -
Knill CJ,
Kennedy JF,
Mistry J,
Miraftab M,
Smart G,
Groocock MR,
Williams HJ
Publication year - 2005
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.1327
Subject(s) - hydrolysis , chemistry , rheometry , rheology , size exclusion chromatography , chitosan , chromatography , shear rate , acid hydrolysis , viscosity , polysaccharide , organic chemistry , chemical engineering , polymer , materials science , composite material , enzyme , engineering
Commercial chitosans were subjected to controlled acid hydrolysis and their degrees of deacetylation (DD), molecular size and rheological flow profiles determined (pre‐ and post‐hydrolysis) by 1 H‐NMR spectroscopy, high‐performance size‐exclusion chromatography and rheometry, respectively. Hydrolysis resulted in DD increases between 4 and 11%. Unhydrolysed chitosans had M w and M n values in the ranges 700–1200 and 130–210 kDa, respectively. Chitosan with the smallest initial molecular size averages had the smallest averages after hydrolysis; however, a chitosan with an intermediate initial molecular size proved to be most resistant to hydrolysis. Molecular size trends were paralleled by zero shear viscosity (η 0 ) measurements determined by application of the Williamson model to rheological flow profile data. Viscosity is obviously related to molecular size, but does not necessarily reflect relative ease of hydrolysis, since specific hydrolysis conditions affect structurally similar polysaccharides in different ways (in terms of rate of depolymerisation and de‐ N ‐acetylation, etc), which are not simply due to differences in molecular size profiles pre‐hydrolysis. Copyright © 2005 Society of Chemical Industry