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Journal articles
Synthesis of new high molecular weight phosphorylated chitosans for improving corrosion protection
Abstract : Two grades of chitosan [chitosan 30000 g mol−1 (N-chitosan 30) and 250000 g mol−1 (N-chitosan 250)] were functionalized by the Kabachnik–Fields reaction. To obtain the highest phosphonic ester grafting rate (55% and 40% for the N-chitosan 30 and N-chitosan 250, respectively), the pH must be kept constant during the reaction (pH=5). Then, a partial hydrolysis of the ester functions was carried out in HCl medium to generate phosphonic acid functions up to 25% and 20% for the N-chitosan 30 and N-chitosan 250, respectively. It was shown that the grafting of phosphonic acids on chitosan significantly reduced the dynamic viscosity. Afterwards, electrochemical impedance measurements were performed in an aqueous solution (pH=5) in the presence of either N-chitosans or P-chitosans (3 wt.%). The two native N-chitosans were little adsorbed onto the carbon steel surface and the corrosion protection was low. In contrast, the impedance results in the presence of the 30000 g mol−1 phosphorylated chitosan (P-chitosan 30) evidenced the beneficial effect of grafted phosphonic acid on its adsorption on the steel surface. The lower efficiency of the 250000 g mol−1 (P-chitosan 250) was attributed to its high molecular weight which made difficult the interactions between the phosphonic groups and the metallic surface.
Cited literature [62 references]
https://hal.archives-ouvertes.fr/hal-02067816
Contributor : Claire Negrell <>
Submitted on : Wednesday, November 6, 2019 - 4:25:45 PM
Last modification on : Tuesday, February 9, 2021 - 11:24:46 AM
Long-term archiving on: : Saturday, February 8, 2020 - 2:58:36 AM
Contributor : Claire Negrell <>
Submitted on : Wednesday, November 6, 2019 - 4:25:45 PM
Last modification on : Tuesday, February 9, 2021 - 11:24:46 AM
Long-term archiving on: : Saturday, February 8, 2020 - 2:58:36 AM
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