Effect of molecular weight and urea on the conformation of chitosan molecules in dilute solutions

Effects of ionic strength on the size and compactness of chitosan nanoparticles

“…2), supports this hypothesis. This is also in accordance with a previous report on the effect of ionic strength on the conformation of chitosan in solution [36], where it was found that the intrinsic viscosity of chitosan decreased with increasing ionic strength of the solution. The authors explained this by the contraction of the chitosan molecules due to increased charge screening in high ionic strength solutions.…”

Chitosan, sisal cellulose, and biocomposite chitosan/sisal cellulose films prepared from thiourea/NaOH aqueous solution

“…Some studies reported that urea seems to affect only polymer-polymer interactions (Cho, Heuzey, Begin, & Carreau, 2006). Tsaih and Chen (1997) showed that the intrinsic viscosity of chitosan increased in solution when 4 M urea was added and that this increase was more pronounced for higher molecular weight chitosan because urea breaks the intra-molecular hydrogen bonds, leads to chitosan in an extended form, and therefore have a higher intrinsic viscosity (Tsaih & Chen, 1997). Chitosan-based films are generally obtained after solubilization of chitosan in acid aqueous solutions.…”

Co-assembly in chitosan–surfactant mixtures: thermodynamics, structures, interfacial properties and applications

“…Concerning chitosan, molecular simulations have shown that the hydrogen bonding between HO(3) group and the O(5) of the next glucosamine unit strongly reduces the flexibility of chitosan [49]. Accordingly, the addition of urea as breaker of the water structure to chitosan solutions affects its conformation in aqueous solution [50,51]. Moreover, chitosan, like cellulose, presents hydrophobic pockets, which play an important role for the interactions with amphiphilic compounds, as discussed later in this review.…”