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Engineering, South Korea

He X.,Institute of Polymer Science
Journal of Polymer Science, Part A: Polymer Chemistry

Surface functionalization of carbon nanotubes (CNTs) with a thermo responsive polymer was achieved via combination of mussel inspired chemistry and surface initiated single electron transfer living radical polymerization (SET-LRP). In this procedure, CNTs were first coated with polydopamine (PDA) through self polymerization under a rather mild condition. And then PDA functionalized CNTs bearing with amino and hydroxyl groups were further reacted with bromo isobutyryl bromide. Finally, a thermo responsive polymer poly(N-isopropylacrylamide) (PNIPAM) was introduced on the CNTs via SET-LRP. The successful surface modification of CNT-PDA-PNIPAM was evidenced by a series of characterization techniques. The resulting CNT-PDA-PNIPAM showed significant enhancement of dispersibility in both aqueous and organic solvents. More importantly, these CNT-polymer nanocomposites showed obvious thermo responsive behavior due to the surface coating CNTs with PNIPAM. As compared with previous methods, this method is not required oxidation of CNTs to introduce funcitonal groups for immobilization of the polymerization initiators. More importantly, this method could also be utilized for fabricating many other polymer nanocomposites because of the strong and universal adhesive of PDA to various materials. It is therefore, the novel strategy via marrying mussel inspired chemistry with SET-LRP should be a simple, general and effective method for surface functionalization. © 2015 Wiley Periodicals, Inc. Source

Guo L.-H.,Institute of Polymer Science | Guo L.-H.,OFCM Institute | Gao H.-Y.,Institute of Polymer Science | Zhang L.,Institute of Polymer Science | And 4 more authors.

Three new iron(II) 2,6-bis(imino)pyridyl complexes bearing bulky and unsymmetrical substituted aniline groups, [2-(CH(CH3)(C 6H5))-4-R1-6-R2-C6H 2N - C(CH3)]2C5H 3NFeCl2 (1, R1 = H, R2 = methyl; 2, R1 = methyl, R2 = methyl; 3, R1 = H, R 2 = methoxy), were synthesized. The unsymmetrical bis(imino)pyridyl ligand L2 contains three isomers that can be detected by 1H NMR and 13C NMR spectroscopy. However, the corresponding complex 2 exhibits only one isomer in solution. X-ray diffraction of 2 confirms that the iron complex adopts a Cs configuration. These complexes activated by methylaluminoxane (MAO) have high catalytic activities for ethylene polymerization and produce linear polyethylenes with bimodal or broad molecular weight distribution. The steric and electronic effects of the ortho substituents on the aniline moiety distinctly affect the molecular weight of the obtained polyethylene. In comparison with 1 and 3, having a single ortho substituent on the aryl rings, and the typical complex 4, containing o-diisopropyl substitution, complex 2 has better thermal stability and produces much higher molecular weight polyethylene. Even at 70 °C, the 2/MAO system still keeps high activity and relatively stable kinetics. © 2010 American Chemical Society. Source

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