基于CH-π相互作用的多壁碳纳米管表面POSS粒子非共价修饰研究

Noncovalent Surface Functionalization of Multi-walled Carbon Nanotubes with Polyhedral Oligomeric Silsesquioxane Nanoparticles Based on CH-π Interactions

首先以α-二亚胺钯(Pd-diimine)在0.1 MPa/35℃下催化乙烯和多面体低聚倍半硅氧烷(POSS)共聚,基于链"行走"机理以一步法工艺获得含有多重POSS的超支化聚乙烯共聚物(HBPE@POSS),随后分别以THF和氯仿为溶剂,在超声下利用所得HBPE@POSS对多壁碳纳米管(MWCNTs)进行表面改性.分别运用核磁共振波谱(1H-NMR)、凝胶渗透色谱(GPC)、广角X射线衍射(WAXD)和热重分析(TGA)技术对所得HBPE@POSS的结构与组成进行了表征,进一步通过紫外-可见吸收光谱(UV-Vis)、透射电子显微镜(TEM)、WAXD、傅立叶红外光谱(FTIR)和TGA技术对MWCNTs的分散浓度、形貌、聚集状态及与聚合物间的非共价作用进行了考察.结果表明,已将POSS引入超支化聚乙烯(HBPE)结构中,比例达39.0 wt%;借助超声,所得HBPE@POSS可实现MWCNTs在THF/氯仿中单根稳定分散,最高浓度达987 mg/L(THF)和511 mg/L(氯仿);利用非共价CH-π作用,可将一定比例的POSS粒子稳固地引入MWCNTs表面.基于该思路,可望在CNTs表面引入更多种类的功能无机纳米粒子,为其表面非共价无机功能化修饰提供新的方法.

One-pot chain walking copolymerization of ethylene and polyhedral oligomeric silsesquioxane （POSS） monomer was first performed at 0. 1 MPa/35℃ with a Pd-diimine catalyst to synthesize hyperbranched polyethylene covalently tethered with multiple POSS nanoparticles （HBPE @ POSS）. The resulting HBPE@ POSS was then used to funetionalize multi-walled carbon nanotubes （MWCNTs） under the assistance of ultrasonieation in tetrahydrofuran （THF） and chloroform, respectively. The structure and POSS portion of the HBPE @ POSS were characterized via proton nuclear magnetic resonance （^1H-NMR）, gel permeation chromatography （GPC）, thermogravimetric analysis （TGA） and wide-angled X-ray diffraction （WAXD） techniques, respectively. Further, the dispersibility, morphology and aggregate state of HBPE@ POSS functionalized MWCNTs, and noncovant interactions investigated through UV-Vis absorbance spectroscopy Fourier-transformed infrared （FTIR） spectroscopy and between MWCNTs and HBPE @ POSS as well, are , transmittance electron microscopy （ TEM ） , WAXD, TGA techniques,respectively. It is testified that POSS can be covalently introduced into hyperbranched polyethylene with a portion of 39.0 wt% in the HBPE@ POSS. The HBPE@ POSS is found to effectively debundle/solubilize MWCNTs both in THF and chloroform, giving stable MWCNTs solutions with concentrations up to 987 mg/L in THF and 511 mg/L in chloroform. Also,it is found that POSS of certain portion can be irreversibly adsorbed onto MWCNTs by means of the noncovalent CH-π interactions between MWCNTs and HBPE @ POSS. It is expected that more inorganic nanoparticles （INPs） can be introduced onto CNTs through this method,thus leading to a novel strategy for surface functionalization of CNTs with INPs.