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Abstract
Chitosan is typically produced by the deacetylation of biopolymer chitin. Its molecular weight (Mw) is a function of the chitin source and the deacetylation conditions. It remains a challenge to both control the Mw of chitosan and obtain good polydispersity, essential for optimal function of chitosan in different applications. This study explores the use of mechanochemistry and aging as effective methods towards the controlled reduction of the Mw of commercial high Mw chitosan (HMwChs) with phosphoric acid where Mw was measured by gel permeation chromatography (GPC). In comparison to conventional solution-based methods, this new mechanochemical process features improved process mass intensity in comparison to conventional techniques and affords low Mw chitosan (LMwChs) samples in a range of 200 to 19.5 kDa, with a polydispersity of 1.8.
Supplementary materials
Title
Supplementary Information
Description
1. Methods
Determination of chitosan Mw S3
Data statistic method S4
2. Supplementary Tables and Figures
Table S1. Mass balance for conditions where the lowest Mw and PDI were achieved S4
Table S2. Comparison of H3PO4 source on Mw reduction of HMwChs S4
Figure S1. Representative 13C NMR spectrum S6
Figure S2. Representative 31P NMR spectrum S7
Figure S3. GPC column calibration plot S7
Table S3. GPC column calibration data points S8
Figure S4. Representative GPC trace S8
Figure S5. TGA of Sigma-Aldrich high molecular chitosan S9
Discussion S1. effect of longer milling time on hydrolysis and temperature S9
Figure S6. Effect of milling time on temperature of the milled medium S10
Figure S7. Effect of milling time and 2 equivalents of 85% H3PO4 on particle size distribution of HMwChs milled in PTFE jar, obtained by granulometry S11
3. Supplementary References
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