Synthesis of poly(diethylaminoethyl methacrylate- co -2,2,6,6-tetramethyl-4-piperidyl methacrylate)s and their segmental
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ORIGINAL CONTRIBUTION
Synthesis of poly(diethylaminoethyl methacrylate-co-2,2,6,6-tetramethyl-4-piperidyl methacrylate)s and their segmental motion study Kaleem-ur-Rahman Naveed 1 & Li Wang 1
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& Haojie Yu & Lisong Teng & Md Alim Uddin & Shah Fahad & Ahsan Nazir
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Received: 22 November 2019 / Revised: 24 July 2020 / Accepted: 3 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA) is a pH-sensitive polymer, while a few recent studies have shown it to possess temperature responsiveness as well. In this article, poly(2-(diethylamino)ethyl methacrylate-co-2,2,6,6-tetramethyl-4piperidyl methacrylate)s, DEA-TMPMs, were synthesized. The TMPM moieties in DEA-TMPMs were subsequently oxidized with hydrogen peroxide to obtain poly(2-(diethylamino)ethyl methacrylate-co-2,2,6,6-tetramethylpiperidine-1-oxyl methacrylate), DEA-TMPs, having nitroxide radicals on the polymer chains. DEA-TMPMs were characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography, differential scanning calorimetry and thermogravimetry techniques, whereas DEA-TMPs were analyzed by Fourier transform infrared spectroscopy, cyclic voltammetry, and electron paramagnetic resonance (EPR) spectroscopy. The results showed that at low pH, the rotational mobility of nitroxide radicals was reduced as EPR spectra mostly consisted of slow-motion component. This slow-motion component in the EPR spectra remained unchanged below neutral pH. These results indicated a sort of interaction among nitroxide radicals and protonated amine groups of DEAEMA monomers. Keywords Electron paramagnetic resonance . Spin–spin interactions . Nitroxide radicals . Diethylaminoethyl methacrylate . Segmental motion
Introduction Poly(2-(diethylamino)ethyl methacrylate), PDEAEMA, has shown to be a pH-sensitive polymer, whereas a few recent reports have revealed it to be a temperature-sensitive polymer as well [1–3]. It is a special smart polymer, which is able to undergo chemical and conformational changes by applying external temperature or pH stimuli [4–8]. It has been shown that PDEAEMA in water changes from a compact conformation to a more extended one due to the increase in electrostatic * Li Wang [email protected] * Haojie Yu [email protected] 1
State Key Laboratory of Chemical Engineering, College of Chemical & Biological Engineering, Zhejiang University, Hangzhou 310027, People’s Republic of China
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Oncological Surgery and Cancer Center, the First Affiliated Hospital, Zhejiang University, Hangzhou 310003, People’s Republic of China
interactions among charged groups on polymer chains. This kind of conformational change is directly related to the functionality of the polycation [9]. It means that the type of interactions of PDEAEMA is variable depending on the conformation of the PDEAEMA chains. If the polymer has an extended conformation, then interactions of polymer with the ionic or non-ionic species (e.g., dyes) would be favorably electrostatic. However, if
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