Synthesis and thermally responsive characteristics of dendritic poly(ether-amide) grafting with PNIPAAm and PEG |
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Authors: | Zhu Yang |
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Affiliation: | Department of Polymer Science and Engineering, University of Science and Technology of China, Hefei, Anhui 230026, PR China |
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Abstract: | A series of thermally responsive dendritic core-shell polymers were prepared based upon dendritic poly(ether-amide) (DPEA), modified with carboxyl end-capped linear poly(N-isopropylacrylamide) (PNIPAAm-COOH) or both PNIPAAm-COOH and carboxyl end-capped methoxy polyethylene glycol (PEG-COOH) in different ratios via an esterification process to obtain DPEA-PNIPAAm or DPEA-PNIPAAm-PEG. Their molecular structures were verified by gel permeation chromatography, and 1H NMR and FTIR spectroscopy. The temperature-dependent characteristics study has revealed that DPEA-PNIPAAm exhibits a lower critical solution temperature (LCST) of about 34 °C, whereas DPEA-PNIPAAm-PEG polymers with the PNIPAAm/PEG ratio of about 1.0 and 0.4 possess about 36 °C and 39 °C, respectively, compared with 32 °C for homopolymer PNIPAAm. The critical aggregation temperature was investigated using fluorescence excitation spectrum of pyrene as a sequestered guest molecule based upon the sharp increase of the I338/I333 value. |
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Keywords: | Poly(N-isopropylacrylamide) Temperature-sensitive Dendritic poly(ether-amide) |
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