Carboxymethyl Chitosan and Its Hydrophobically Modified Derivative as pH-Switchable Emulsifiers

Abstract

The emulsification properties of carboxymethyl chitosan (CMChi) and hydrophobically modified carboxymethyl chitosan (h-CMChi) were studied as a function of pH and dodecane/water ratio. The pH was varied between 6—10, and the oil/water ratio between 0.1—2.0. In CMChi solution, the emulsion stability increased as the pH was lowered from 10 to 7, and the phase inversion was shifted from oil/water ratio 1.0 to 1.8, respectively. The system behaved differently in pH 6 due to the aggregation of CMChi and the formation of nanoparticles (∼200—300 nm). No phase inversion was observed and the maximum amount of emulsified oil was reached at oil/water ratio 1.2. The h-CMChi showed similar behavior as a function of pH but, due to hydrophobic modification, the phase inversion was shifted to higher values in pH 7—10. In pH 6, the behavior was similar, but the maximum amount of emulsified oil was higher compared to CMChi. The amount of adsorbed particles correlated with the emulsified amount of oil. Reversible emulsification of dodecane was demonstrated by pH adjustment using CMChi and h-CMChi solutions. The formed emulsions were gel-like, suggesting particle–particle interaction.

Pickering/Non‐Pickering Emulsions of Nanostructured Sulfonated Lignin Derivatives

“…However, the results are not completely comparable technically, mainly because R h determines the hydrodynamic size of N‐SEKL in solution, whereas TEM shows the size of particles in a dried state. The drying of polymeric precipitates is expected to affect the size and shape of the particles . It should be noted that nanoparticles were not observed for dried samples at pH 7 and 11 upon implementing TEM visualization and a uniform film of SEKL was formed in the dried state (Figure S6).…”

“…The drying of polymeric precipitates is expected to affect the size and shape of the particles. [34] It should be noted that nanoparticles were not observed for dried samples at pH 7a nd 11 upon implementing TEM visualization and au niform film of SEKL was formed in the dried state ( Figure S6).…”

“…Comparatively, one of the simplest approaches to enhance emulsion properties is the use of solid particles for the formulation of Pickering emulsions through protonation/deprotonation of the functional groups of the emulsifiers, which is known to alter the wettability of the emulsifiers . Such measures were previously reported by Kalliola et al., who used the precipitation of carboxymethylated chitosan to prepare stable Pickering emulsions.…”

Preparation of Silk Fibroin/Carboxymethyl Chitosan Hydrogel under Low Voltage as a Wound Dressing

“…The theoretical viscosity of the prepared SF/CMCS mixture can be calculated as 19.96 mpa•s, which is smaller than the experimental data, indicating that some interaction has occurred between SF and CMCS. Because the carboxyl groups (pKa = 4.5) [36] of CMCS and SF (pI = 4.5) [37] are predominantly negatively charged at the pH of the mixture (pH = 8.76), the formation of an electrostatic interaction between SF and CMCS is less favorable. We believe this difference in the calculated theoretical and experimental viscosities of the SF/CMCS mixture was mainly due to the formation of hydrogen bonds between SF and CMCS, as the rheological behavior of an aqueous polymer mainly depends on the relative strength of the hydrogen bonding within the solution, and more strong hydrogen bonds would greatly increase the viscosity [38,39].…”

Synthesis and characterization of β-cyclodextrin/carboxymethyl chitosan/hydroxyapatite fused with date seed extract nanocomposite scaffolds for regenerative bone tissue engineering

“…2C]. In case of CH, the average particle size varied in the range of 30-35 nm and the particles were observed to be comparatively crowded resulting in the formation of aggregated structure 45,32 . The consistent dispersion of particles in case of the proposed nanocomposite scaffolds may be due to the interactions of DSE with the CMC, NHA and β-CD.…”