Molecular weight reduction can be done by several methods,

1) treat the chitosan with 50%(w/w) NaOH for 3-4 hrs at 90-110 temperature will lead to controlled reduction in molecular weight.

2) Dissolve the chitosan in acetic acid and heat the solution and again precipitate with dilute alkali

3) Sonication of chitosan solution

4) Pressure treatment etc.

K.A. Martin Xavier, any references?

Please ref

https://doi.org/10.1016/j.polymdegradstab.2012.12.028

https://doi.org/10.1016/j.carbpol.2017.03.006

Thanks so much