Jang Jyongsik, Yoon Hyeonseok
Hyperstructured Organic Materials Research Center, School of Chemical and Biological Engineering, College of Engineering, Seoul National University, Shinlimdong 56-1, Seoul 151-742, Korea.
Langmuir. 2005 Nov 22;21(24):11484-9. doi: 10.1021/la051447u.
Polypyrrole (PPy) nanotubes were readily fabricated through chemical oxidation polymerization in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse (water-in-oil) emulsions. The reverse cylindrical micelle phase was characterized, and the key factors affecting the formation of PPy nanotubes were systematically inspected. AOT reverse cylindrical micelles were prepared via a cooperative interaction between an aqueous FeCl3 solution and AOT in an apolar solvent. In the H2O/FeCl3/AOT/apolar solvent system, the aqueous FeCl3 solution played a role in increasing the ionic strength and decreasing the second critical micelle concentration of AOT. As a result, AOT reverse cylindrical micelles could be spontaneously formed in an apolar solvent. In addition, iron cations were adsorbed to the anionic AOT headgroups that were capable of extracting metal cations from the aqueous core. Under these conditions, the addition of pyrrole monomer resulted in the chemical oxidation polymerization of the corresponding monomer at the surface of AOT reverse cylindrical micelles, followed by the formation of tubular PPy nanostructures. In a typical composition (74.0 wt % hexane, 22.4 wt % AOT, and 3.6 wt % aqueous FeCl3 solution at 15 degrees C), the average diameter of PPy nanotubes was approximately 94 nm and their length was more than 2 mum. The PPy nanotube dimensions were affected by synthetic variables such as the weight ratio of aqueous FeCl3 solution/AOT, type of apolar solvent, and reaction temperature. Moreover, the relationship between the diameter and the conductivity of the nanotubes was investigated.
聚吡咯(PPy)纳米管可通过在双(2-乙基己基)磺基琥珀酸钠(AOT)反相(油包水)乳液中进行化学氧化聚合轻松制备。对反相圆柱形胶束相进行了表征,并系统研究了影响PPy纳米管形成的关键因素。AOT反相圆柱形胶束是通过氯化铁水溶液与AOT在非极性溶剂中的协同相互作用制备的。在H₂O/FeCl₃/AOT/非极性溶剂体系中,氯化铁水溶液起到了提高离子强度和降低AOT的第二临界胶束浓度的作用。结果,AOT反相圆柱形胶束可在非极性溶剂中自发形成。此外,铁阳离子吸附在能够从水核中萃取金属阳离子的阴离子AOT头基上。在这些条件下,加入吡咯单体导致相应单体在AOT反相圆柱形胶束表面发生化学氧化聚合,随后形成管状PPy纳米结构。在典型组成(15℃下74.0 wt%己烷、22.4 wt%AOT和3.6 wt%氯化铁水溶液)中,PPy纳米管的平均直径约为94 nm,长度超过2μm。PPy纳米管的尺寸受合成变量影响,如氯化铁水溶液/AOT的重量比、非极性溶剂类型和反应温度。此外,还研究了纳米管直径与电导率之间的关系。