Temperature and Salt Responsive Amphoteric Nanogels Based on N-Isopropylacrylamide, 2-Acrylamido-2-methyl-1-propanesulfonic Acid Sodium Salt and (3-Acrylamidopropyl) Trimethylammonium Chloride
Ayazbayeva A.Y. Shakhvorostov A.V. Gussenov I.S. Seilkhanov T.M. Aseyev V.O. Kudaibergenov S.E.
July 2022MDPI
Nanomaterials
2022#12Issue 14
Polyampholyte nanogels based on N-isopropylacrylamide (NIPAM), (3-acrylamidopropyl) trimethylammonium chloride (APTAC) and 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) were synthesized via conventional redox-initiated free radical copolymerization. The resultant nanogels of various compositions, specifically [NIPAM]:[APTAC]:[AMPS] = 90:5:5; 90:7.5:2.5; 90:2.5:7.5 mol.%, herein abbreviated as NIPAM90-APTAC5-AMPS5, NIPAM90-APTAC7.5-AMPS2.5 and NIPAM90-APTAC2.5-AMPS7.5, were characterized by a combination of 1H NMR and FTIR spectroscopy, TGA, UV–Vis, DLS and zeta potential measurements. The temperature and salt-responsive properties of amphoteric nanogels were studied in aqueous and saline solutions in a temperature range from 25 to 60 °C and at ionic strengths (μ) of 10−3 to 1M NaCl. Volume phase transition temperatures (VPTT) of the charge-balanced nanogel were found to reach a maximum upon the addition of salt, whereas the same parameter for the charge-imbalanced nanogels exhibited a sharp decrease at higher saline concentrations. A wide bimodal distribution of average hydrodynamic sizes of nanogel particles had a tendency to transform to a narrow monomodal peak at elevated temperatures and higher ionic strengths. According to the DLS results, increasing ionic strength results in the clumping of nanogel particles.
hydrophobic/hydrophilic balance , phase transition temperature , polyampholyte nanogels , salt response , thermal response
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Laboratory of Functional Polymers, Institute of Polymer Materials and Technology, Almaty, 050019, Kazakhstan
Department of Chemical and Biochemical Engineering, Satbayev University, Almaty, 050013, Kazakhstan
Laboratory of NMR-Spectroscopy, Sh. Ualikhanov University, Kokshetau, 020000, Kazakhstan
Department of Chemistry, University of Helsinki, Helsinki, 00014, Finland
Laboratory of Functional Polymers
Department of Chemical and Biochemical Engineering
Laboratory of NMR-Spectroscopy
Department of Chemistry
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