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Cusola O.,Laboratory of Pulp and Paper Science LGP2 | Cusola O.,Polytechnic University of Catalonia | Tabary N.,Laboratory of Pulp and Paper Science LGP2 | Tabary N.,Lille University of Science and Technology | And 2 more authors.
Journal of Applied Polymer Science | Year: 2013

Several cellulosic substrates have been surface-functionalized with cyclomaltoheptaose (β-cyclodextrin, β-CD) using citric acid as a crosslinker agent to obtain new surface-modified materials able to release antiseptic molecules over a prolonged period, in view of their use in medical domain. Three different commercial cellulosic substrates were used, namely: (i) an uncoated paper, (ii) a crepe paper, and (iii) a medical bandage. They were successfully grafted by a crosslinked polymer consisting on β-CD molecules as assessed by scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Several time-temperature kinetic cycles were performed to reach the optimum curing parameters. The grafted and nongrafted samples were loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent. The drug-delivery kinetics of the encapsulated digCHX was carried out by immersing the sample under investigation into an aqueous medium, and the quantity of the released digCHX was measured, as a function of time, by UV spectroscopy. The optimal grafting conditions were established on the basis of the highest weight gain. These samples did not give the best release performance. Nevertheless, several grafted substrates were able to uptake an appreciable amount of active molecules and release them over a prolonged time of about 20 days. Copyright © 2012 Wiley Periodicals, Inc.

Missoum K.,Laboratory of Pulp and Paper Science LGP2 | Bras J.,Laboratory of Pulp and Paper Science LGP2 | Belgacem M.N.,Laboratory of Pulp and Paper Science LGP2
Cellulose | Year: 2012

Chemical surface modification of nanofibrillated cellulose (NFC) was performed using a long aliphatic isocyanate chain. Different molar ratios of the coupling agents were tested, i. e., 1, 10, 30 equivalents with respect to hydroxyl groups of the NFC surface. FE-SEM analyses revealed that there were no changes in their morphology thus keeping nanofibril-like structure with about 30 nm of diameter. All these samples were characterized by different techniques (e. g., FTIR) to check the efficiency of the grafting. Hydrophobic NFC were achieved whatever the grafting agent ratio. The Degree of Substitution was determined by Elemental Analyses and the Degree of Substitution of the Surface was calculated thanks to X-ray Photoelectron Spectroscopy data. Combining these two techniques, the Internal Degree of Substitution was proposed for the first time. It indicates if the modification occurs also within NFC internal layers. Surface (contact angle), rheological (water suspension viscosity) and thermal properties (ThermoGravimetric Analysis) of grafted NFC do not follow the expected linear evolution of properties with the increase of molar ratio. X-Ray Diffraction analyses showed that the grafted aliphatic chains display crystalline waxy domains at some ratios. A model for aliphatic chain organization at the surface is proposed and clearly explained for the first time why a compromise in molar ratio is necessary to achieve best properties. © 2012 Springer Science+Business Media B.V.

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