Insightful understanding of the role of clay topology on the stability of biomimetic hybrid chitosan-clay thin films and CO2-dried porous aerogel microspheres.
Three natural clay-based microstructures, namely layered montmorillonite (MMT), nanotubular halloysite (HNT) and micro-fibrillar sepiolite (SP) were used for the synthesis of hybrid chitosan-clay thin films and porous aerogel microspheres. At a first glance, a decrease in the viscosity of the three gel-forming solutions was noticed as a result of breaking the mutual polymeric chains interaction by the clay microstructure. Upon casting, chitosan-clay films displayed enhanced hydrophilicity in the order CS<CS-MMT<CS-HNT<CS-SP. Irrespective to the clay microstructure, an improvement in the mechanical properties of the chitosan-clay films has been substantiated with CS-SP reaching the highest value at 5% clay loading. While clay addition provides a way to resist the shrinkage occurring for native chitosan, the enhanced hydrophilicity associated to the water content affects the efficacy of the CO2 super-critical drying as the most hydrophilic CS-SP microspheres face the highest shrinkage, resulting in a lowest specific surface area compared to CS-HNT and CS-MMT. Chitosan-clay exhibits enhanced thermal properties with the degradation delayed in the order CS<CS-MMT<CS-HNT<CS-SP. Under acidic environment, a longevity has been substantiated for chitosan-clay compared to native chitosan, evidencing the beneficial protective effect of the clay particulates for the biopolymer. However, under hydrothermal treatment, the presence of clay was found to be detrimental to the material stability as a significant shrinkage occurs in hybrid CS-clay microspheres, which is attributed again to their increased hydrophilicity compared to the native polymeric microspheres. In this framework, a peculiar behavior was observed for CS-MMT, with the microspheres standing both against contraction during CO2 gel drying and under hydrothermal conditions. The knowledge gained from this rational design will constitute a guideline toward the preparation of ultra-stable, practically-optimized food-packaging films and commercially scalable porous bio-based adsorbents.
Euromed Research Center, Engineering Division, Euro-Mediterranean University of Fes (UEMF), Fès-Shore, Route de Sidi Hrazem, 30070 Fès, Morocco; Instituto de Tecnología Química (CSIC-UPV) and Departamento de Química, (UPV), Av. de los Naranjos s/n, 46022 Valencia, Spain; Laboratory of Organometallic and Macromolecular Chemistry-Composites Materials, Faculty of Sciences and Technologies, Cadi Ayyad University, Avenue Abdelkrim Elkhattabi, B.P. 549, 40000 Marrakech, Morocco.
Sana
S
Frindy
Instituto de Tecnología Química (CSIC-UPV) and Departamento de Química, (UPV), Av. de los Naranjos s/n, 46022 Valencia, Spain.
Ana
A
Primo
Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Institute of Nanomaterials and Nanotechnology (NANOTECH), Laboratory of Polymer Processing, Rabat, Morocco.
Abou El Kacem
Ael K
Qaiss
Moroccan Foundation for Advanced Science, Innovation and Research (MAScIR), Institute of Nanomaterials and Nanotechnology (NANOTECH), Laboratory of Polymer Processing, Rabat, Morocco.
Rachid
R
Bouhfid
Laboratory of Organometallic and Macromolecular Chemistry-Composites Materials, Faculty of Sciences and Technologies, Cadi Ayyad University, Avenue Abdelkrim Elkhattabi, B.P. 549, 40000 Marrakech, Morocco.
Mohamed
M
Lahcini
Instituto de Tecnología Química (CSIC-UPV) and Departamento de Química, (UPV), Av. de los Naranjos s/n, 46022 Valencia, Spain.
Hermenegildo
H
Garcia
Euromed Research Center, Engineering Division, Euro-Mediterranean University of Fes (UEMF), Fès-Shore, Route de Sidi Hrazem, 30070 Fès, Morocco.
Mosto
M
Bousmina
Euromed Research Center, Engineering Division, Euro-Mediterranean University of Fes (UEMF), Fès-Shore, Route de Sidi Hrazem, 30070 Fès, Morocco. Electronic address: a.elkadib@ueuromed.org.
Abdelkrim
A
El Kadib
D000538:Aluminum Silicates / Q000737:chemistry*; D032701:Biomimetics; D002245:Carbon Dioxide / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D000077215:Clay; D018857:Food Packaging; D005782:Gels; D008863:Microspheres; D016062:Porosity; D014867:Water
D000538:Aluminum Silicates; D005782:Gels; D014867:Water; D002245:Carbon Dioxide; D048271:Chitosan; D000077215:Clay
Chitosan; Halloysite; Montmorillonite; Porous microspheres; Sepiolite; Stability; Super-critical drying; Thin films