Hydrophobic Modification of Chitosan via Reactive Solvent-Free Extrusion

Abstract

Hydrophobic derivatives of polysaccharides possess an amphiphilic behavior and are widely used as rheological modifiers, selective sorbents, and stabilizers for compositions intended for various applications. In this work, we studied the mechanochemical reactions of chitosan alkylation when interacting with docosylglycidyl and hexadecylglycidyl ethers in the absence of solvents at shear deformation in a pilot twin-screw extruder. The chemical structure and physical properties of the obtained derivatives were characterized by elemental analysis, FT-IR spectroscopy, dynamic light scattering, scanning electron microscopy, and mechanical tests. According to calculations for products soluble in aqueous media, it was possible to introduce about 5–12 hydrophobic fragments per chitosan macromolecule with a degree of polymerization of 500–2000. The length of the carbon chain of the alkyl substituent significantly affects its reactivity under the chosen conditions of mechanochemical synthesis. It was shown that modification disturbs the packing ability of the macromolecules, resulting in an increase of plasticity and drop in the elastic modulus of the film made from the hydrophobically modified chitosan samples.

Chitin Nanocrystals Provide Antioxidant Activity to Polylactic Acid Films

“…In contrast, chitin nanocrystals are heat stable up to 250–300 °C [ 62 , 63 ] and, therefore, are better candidates for the production of active packages. When comparing chitosan with chitin nanoparticles, chitin has better miscibility than hydrophobic polylactic acid (chitosan is more hydrophilic) [ 64 , 65 ], which has been linked to improved mechanical and barrier properties [ 66 , 67 , 68 , 69 ].…”

Chitosan Nanoparticles for Gastroesophageal Reflux Disease Treatment

“…Hydrophobization is usually carried out by introducing alkyl substituents of various lengths into the structure of CS due to reactions of its amino groups with fatty acids or their anhydrides (acylated derivatives) or by interaction with aldehydes followed by the reduction of azomethine bonds to secondary amines (alkylated derivatives) [ 133 ]. These hydrophobically modified CSs can create self-assembled nanoparticles to encase hydrophobic drugs in their core [ 134 , 135 ].…”

Coating of silver nanoparticles on polyurethane film surface by green chemistry approach and investigation of antibacterial activity against S. epidermidis

“…The band at 1070 cm −1 is attributed to C-O stretching vibrations of the CHOH, and CH 2 OH groups in the ring. [64][65][66][67] Attachment of silver nanoparticles to the CH modified film surfaces caused the significant decrease in intensity of OH and NH 2 stretching band region, which indicates the chelation of silver with both amino and hydroxyl groups of chitosan. The shift of the characteristic C=O, N-H, and C-O bands of chitosan to 1664, 1598, and 1080 cm −1 , respectively, and the decrease in their intensity suggested that it is an effect of the existence of interactions between Ag and O, N atoms of OH and NH 2 groups.…”