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Open AccessArticle

Control of pH-Responsiveness in Graphene Oxide Grafted with Poly-DEAEMA via Tailored Functionalization

1
School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, Coyoacán, Mexico City 04510, Mexico
2
Escuela Nacional Preparatoria 8 Miguel E. Schulz, Lomas de Plateros s/n, Álvaro Obregón, Mexico City 01600, Mexico
*
Authors to whom correspondence should be addressed.
Nanomaterials 2020, 10(4), 614; https://doi.org/10.3390/nano10040614
Received: 15 February 2020 / Revised: 23 March 2020 / Accepted: 24 March 2020 / Published: 27 March 2020
(This article belongs to the Special Issue Surface Modifications of Carbon Nanomaterials)
Polymer-grafted nanomaterials based on carbon allotropes and their derivatives (graphene oxide (GO), etc.) are typically prepared by successive reaction stages that depend upon the initial functionalities in the nanostructure and the polymerization type needed for grafting. However, due to the multiple variables involved in the functionalization steps, it is commonly difficult to predict the properties in the final product and to correlate the material history with its final performance. In this work, we explored the steps needed to graft the carboxylic acid moieties in GO ([email protected]) with a pH-sensitive polymer, poly[2-(diethylamino)ethyl methacrylate] (poly[DEAEMA]), varying the reactant ratios at each stage prior to polymerization. We studied the combinatorial relationship between these variables and the behavior of the novel grafted material GO-g-poly[DEAEMA], in terms of swelling ratio vs. pH (%Q) in solid specimens and potentiometric response vs. Log[H+] in a solid-state sensor format. We first introduced N-hydroxysuccinimide (NHS)-ester moieties at the –COOH groups (GO-g-NHS) by a classical activation with N-ethyl-N′-(3-dimethylaminopropyl)carbodiimide (EDC). Then, we substituted the NHS-ester groups by polymerizable amide-linked acrylic moieties using 2-aminoethyl methacrylate (AEMA) at different ratios to finally introduce the polymer chains via radical polymerization in an excess of DEAEMA monomer. We found correlated trends in swelling pH range, interval of maximum and minimum swelling values, response in potentiometry and potentiometric linear range vs. Log[H+] and could establish their relationship with the combinatorial stoichiometries in synthetic stages. View Full-Text
Keywords: graphene oxide; DEAEMA; radical polymerization; pH-sensitive materials; swelling ratio; potentiometry graphene oxide; DEAEMA; radical polymerization; pH-sensitive materials; swelling ratio; potentiometry
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MDPI and ACS Style

Noriega-Navarro, R.; Castro-Medina, J.; Escárcega-Bobadilla, M.V.; Zelada-Guillén, G.A. Control of pH-Responsiveness in Graphene Oxide Grafted with Poly-DEAEMA via Tailored Functionalization. Nanomaterials 2020, 10, 614.

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