Aspartic acid in a new role: Synthesis and application of a pH-responsive cyclopolymer containing residues of the amino acid |
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| Affiliation: | 1. Holzforschung Austria, Franz-Grill-Strasse 7, 1030 Vienna, Austria;2. Institute of Wood Science and Technology, University of Natural Resources and Life Sciences, Konrad-Lorenz-Straße 24, 3430 Tulln an der Donau, Austria;1. Department of Chemistry, The IIS University, Jaipur 302020, India;2. Department of Chemistry, University of Hyderabad, Hyderabad 500046, India;3. Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Postfach 3329, D-38023 Braunschweig, Germany;1. Key Laboratory for Special Functional Materials of Ministry of Education, Collaborative Innovation Center of Nano Functional Materials and Applications, Henan University, Kaifeng 475004, China;1. School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Qld 4811, Australia;2. Ondokuz Mayıs University, Education Faculty, Department of Science Education, Kurupelit, Samsun, Turkey;1. Eindhoven University of Technology, Process Systems Engineering Group, PO Box 513, Eindhoven 5600 MB, The Netherlands;2. Institute for Sustainable Process Technology, Groen van Prinstererlaan 37, Amersfoort 3818 JN, The Netherlands;3. University of Twente, Sustainable Process Technology Group, Green Energy Initiative, Faculty of Science and Technology, PO Box 217, Enschede 7500 AE, The Netherlands;4. Delft University of Technology, Faculty of Applied Sciences, Department of Chemical Engineering, Julianalaan 136, Delft 2628 BL, The Netherlands |
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| Abstract: | The reaction between diallylamine and dimethyl maleate afforded the Michael addition product dimethyl N,N-diallylaspartate (CH2 CH–CH2)2NCH(CO2Me)CH2CO2Me] I, which upon treatment with dry HCl and ester hydrolysis with aqueous HCl gave its hydrochloride salt (CH2CH–CH2)2NH+CH(CO2Me)CH2CO2Me Cl−] II and N,N-diallylaspartic acid hydrochloride (CH2CH–CH2)2NH+CH(CO2H)CH2CO2H Cl−] III, respectively. The new monomers II and III underwent cyclopolymerization to give, respectively, cationic polyelectrolytes (CPEs) poly(II) and poly(III). Under the influence of pH, triprotic acid (+) poly(III) was equilibrated to water-insoluble diprotic polyzwitterionic acid (±) IV, water-soluble monoprotic poly(zwitterion–anion) (± −) V, and its conjugate base polydianion (=) VI. The protonation constants of the carboxyl group and trivalent nitrogen in VI have been determined. A 20-ppm concentration of IV is effective in inhibiting the precipitation of CaSO4 from its supersaturated solution with an ≈ 100% scale inhibition efficiency for a duration of 50 h at 40 °C. The aqueous two-phase systems (ATPSs) of VI and polyoxyethylene have been studied. The transformation of water-soluble VI to insoluble IV makes it a recycling ATPS as it can be recycled by precipitation at a lower pH. |
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