A triblock PEG-based polymer (CP1113) with a clear ABA structure was synthesized from 1,13-tridecanedioic acid (DA13) and mono-methoxy-poly(ethylene glycol) (MePEG) via condensation reaction. An inclusion complex (IC1113) with b-cyclodextrin (CD) was prepared by co-precipitation and the IC formation was confirmed by transmittance determination with a UV-Vis spectrometer. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetry analysis (TGA) were adopted to characterize IC1113 and the experimental data showed that a channel-type polypseudorotaxane was formed. For further investigating the inclusion behaviors, 1 H-NMR spectroscopy was used to determine the molar ratio between CP1113 and b-CD and 2D ROSEY spectra were recorded to elucidate the IC formation mechanism. The results revealed that b-CD threaded onto the polymer main chain at a molar ratio of 7.8 : 1 and the molar ratio of EG segments to b-CD in IC1113 was ca. 8.28 : 1. It was concluded that b-CD accommodated both the methylene and the PEG segments and herein hydrophobic and hydrogenbonds interactions played the most important roles with a hydrophobic stabilizing and hydrogen-bond inducing effect, which "amplified" the hydrophobic interaction between b-CD and the methylene segment along the hydrophilic PEG segments.
With a similar composition but different monomer sequence distributions in the copolymer backbones, two poly(N-isopropylacrylamide)-g-poly(ethylene oxide) (PNIPAM-g-PEO) copolymers were synthesized at different temperatures of 29 and 45 °C, in the presence of which Ag nanoparticles (NPs) were successfully prepared by in situ reduction at 25 and 41 °C, respectively. The experimental results show that both the copolymers can effectively stabilize Ag NPs, and the copolymer PNIPAM-g-PEO/45 has a better stabilizing and dispersing effect when the preparation temperature of Ag NPs is 25 °C.
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