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Item type:Publication, A simple approach to produce tailor-made chitosans with specific degrees of acetylation and molecular weights(MDPI AG, 2021-08-01)Chitin is a structural polysaccharide that is found in crustaceans, insects, fungi and some yeasts. Chitin deacetylation produces chitosan, a well-studied biopolymer with reported chemical and biological properties for diverse potential applications for drug delivery, metal ion absorption, scaffolds and tissue engineering. Most known properties of chitosan have been determined from samples obtained from a variety of sources and in different conditions, this is, from chitosans with a wide range of degrees of N-acetylation (DA) and molecular weight (MW). However, as for any copolymer, the physicochemical and mechanical characteristics of chitosan highly depend on their monomer composition (DA) and chain size (MW). This work presents a simple methodology to produce chitosans with specific and predictive DA and MW. Reaction with acetic anhydride proved to be an efficient method to control the acetylation of chitosan, DAs between 10.6% and 50.6% were reproducibly obtained. In addition to this, MWs of chitosan chains were reduced in a controlled manner in two ways, by ultrasound and by acidic hydrolysis at different temperatures, samples with MWs between 130 kDa and 1300 kDa were obtained. DAs were determined by 1H-NMR and MWs by gel permeation chromatography. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Evaluation of Chitosan and Potato Starch as Stabilizers to Improve the Mechanical and Water Durability Properties of Printable Earth-Based Matrices Reinforced with Sisal Fibers(Trans Tech Publications Ltd, 2023-01-01)Due to economic, sustainable, and aesthetic benefits, academia and the construction industry are exploring the use of earth in modern construction is being widely studied. Unfortunately, earth as a construction material has low mechanical, poor water durability resistance, and the potential to swell and crack. Therefore, this paper evaluates chitosan and potato starch, natural biodegradable polymers, as stabilizers to improve mechanical strength and water durability resistance of printable earth-based matrix reinforced with sisal fibers. Although the test results indicated that the chitosan had a better performance as an earth stabilizer than potato starch, adding both stabilizers resulted in earthen composites with higher compressive strength and lower water permeability. These results demonstrate the feasibility of using natural stabilizers to improve the performance of earth-based materials for 3D printing without affecting their printability capacities. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Additive Construction Using Enhanced Earthen-Based Composites: Improvement of the Mechanical Strength and Water Durability Using Chitosan and Agave Fibers(RELX Group (Netherlands), 2023-01-01) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Chitosan Eco-Friendly Approach to Oil Spill Cleanup: A Combined 2D TD-NMR Relaxation and Computational Modeling Study(Springer Science+Business Media, 2026-01-01)This work investigates the molecular interaction between chitosan, an effective and eco-friendly biopolymer, and crude oil components within petroleum emulsions. This mechanistic investigation combines 2D TD-NMR relaxation and computational modeling to understand chitosan’s role as an adsorbent and demulsifier for applications in environmental remediation. We applied a medium molecular mass chitosan to a series of six petroleum emulsions, spanning a representative range of medium and heavy crude oils (viscosities from 32.52 to 182.07 mm2.s-1 at 20 °C). The 2D D-T2 correlation maps were generated using the PFG-CPMG (Pulsed Field Gradient-Carr-Purcell-Meiboom-Gill) sequence to resolve the changes in oil and water mobility following chitosan addition. The key result is the observation of a characteristic shift in the diffusion coefficient (D) and transverse relaxation time (T2) of the oil component upon chitosan introduction. This shift provides direct evidence of the molecular interaction and the disruption of the emulsion stabilizing film. Furthermore, molecular modeling confirms strong water binding, complementing the TD-NMR findings. Overall, the study successfully demonstrates the utility of TD-NMR and molecular dynamics for mechanistic assessment, providing crucial, direct insight into the demulsification role of chitosan within petroleum emulsions.