Density functional theory calculations on the grafting copolymerization of 2-substituted aniline onto chitosan
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Density functional theory calculations on the grafting copolymerization of 2‑substituted aniline onto chitosan M. S. Ibrahim1 · H. R. Abd El‑Mageed2 · H. M. Abd El‑Salam2 Received: 15 June 2019 / Revised: 14 December 2019 / Accepted: 17 December 2019 © Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract Chitosan is a biodegradable natural polymer which is safe and non-toxic and used in different applications. Grafting of chitosan with aniline derivatives is an important route to improve its properties. Chitosan has different active groups that can be blocked in the grafting process, which could be confirmed by calculation studies. The author thinks that the confirmation of chitosan active group included in the grafting by calculations is not given before. So authors give evidence to the direction of grafting and mechanism. Poly(2-methylaniline) (P2-MA), poly(2-hydroxyaniline) (P2-HA) and their copolymers are used in the present study. Quantum mechanics calculations using density functional theory were applied to study the grafting process. The obtained data reveal that grafting occurs at NH2 groups, which is less energetic (2.04). This conclusion confirms the experimental studies. Computational calculations show that the interaction between chitosan and both P2-MA and P2-HA takes place at the NH2 group of chitosan with high stabilization energy (− 1346.7746). A complete next-to-leading order (NLO) values show that the graft could be a better candidate for NLO application (42.25 kcal mol−1) global properties (hardness). Also, the grafting process gives high reactive products due to a decrease in band gap energy. Keywords Grafting · Density functional theory · Aniline derivatives
Introduction The wide-range application of both polyaniline and chitosan has been limited because of their poor processability. The substitution of alkyl groups at phenylene carbon or nitrogen was studied to enhance the solubility of polyaniline in an organic * M. S. Ibrahim [email protected] 1
Holding Company for Water and Waste Water, Cornish El Nil, Beni‑Suef 62513, Egypt
2
Department of Chemistry, Faculty of Science, Polymer Research Laboratory, Beni-Suef University, Beni‑Suef 62514, Egypt
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Polymer Bulletin
solvent [1–16]. Grafting of both polyaniline and its derivatives onto the chitosan surface has shown enhancement in chitosan properties such as solubility, bioactivities [17–19], chelating properties [20, 21], bacteriostatic effect [22], adsorption properties [23], mucoadhesivity [24], biocompatibility [25] and biodegradability [26]. They have reported that aniline could be copolymerized with 2-methylaniline to give a copolymer film, of which conductivity could be controlled in a broad range. Copolymerization of aniline with N-butylaniline, 2-methylaniline and N-methylaniline has been reported [27–29]. Chitosan is a semicrystalline polymer that exhibits polymorphism with different DD and Mw [30]. Chitosan includes NH2 and OH groups in the main backbone that give acti
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