溶剂对聚(对亚苯基亚乙炔基-alt-间亚苯基亚乙炔基)螺旋缠绕单壁碳纳米管的影响

Effects of Solvent on Helical Wrapping of Single-walled Carbon Nanotubes by Poly(p-phenyleneethynylene-alt-m-phenyleneethynylene)

水溶性聚(对亚苯基亚乙炔基-alt-间亚苯基亚乙炔基)(meta-PPEs)可与单壁碳纳米管(SWCNTs)组装成螺旋缠绕复合结构,从而改善SWCNTs的溶解性并实现选择性分离.为深入理解这种明确形态超分子结构的形成机理,本文利用阳离子型水溶性meta-PPE-N^(+)Et_(2)Me与SWCNTs在不同比例二甲基亚砜/水(DMSO/H_(2)O)的混合溶剂中制备复合材料,深入探索聚合物结构、溶剂成分对复合结构形态和稳定性的影响.通过紫外-可见-近红外吸收光谱、荧光发射光谱、透射电镜、拉曼光谱和红外光谱等研究表明,当DMSO比例为70%时,该聚合物呈现从无规线团到螺旋构象的突变;此时自组装形成螺旋构象的驱动力较大,因此聚合物在自身开始形成螺旋疏水空腔的过程中对SWCNTs产生螺旋缠绕,疏水效应和π-π作用进一步增强,形成稳定的复合材料;然而在其他比例混合溶剂中并没有形成明显的螺旋缠绕超分子结构.该研究结果将为SWCNTs的可控修饰和应用提升提供一定的理论指导.

Water-soluble poly(p-phenyleneethynylene-alt-m-phenyleneethynylene)s(meta-PPEs)can wrap singlewalled carbon nanotubes(SWCNTs)helically to improve the solubility of SWCNTs and realize highly selective dispersion.In order to deeply understand the formation mechanism of such well-defined supermolecular structure,we prepared the composites of SWCNTs and the cationic water-soluble meta-PPE-N^(+)Et_(2)Me in DMSO/H_(2)O mixed solvents with different ratios.The effects of polymer structure and composition of mixed solvents on the morphology and stability of the composite structure were deeply explored.Studies on the ultraviolet-visiblenear infrared absorption spectroscopy,fluorescence spectroscopy,transmission electron microscopy,Raman spectroscopy and infrared spectroscopy showed that,when the ratio of DMSO was 70%,the polymer exhibited a sudden change from random coil to helical conformation.At this time,the driving force to self-assemble into helical conformation was relatively large,so the polymer wrapped SWCNTs helically in the process of forming a helical hydrophobic cavity itself,and the hydrophobic effect and π-π interaction were further enhanced to form a stable composite.However,no obvious helical wrapping supermolecular structure was formed in the mixed solvents with other ratios.These results will provide some theoretical guidance for the controllable modification and application improvement of SWCNTs.