Functionalization of MWNTs with 4-Fluorobenzenesulfonyl Chloride in Polyphosphoric Acid

Abstract

To achieve maximum enhanced physical properties via nanoscale reinforcing additives, there are two major issues related to the aspect ratio through dispersion and interfacial adhesion between additives and matrix. Thus, there have been various efforts to provide homogeneous dispersion of one-dimensional carbon nano materials into multi-component matrix via physical, chemical, or combined approaches. However, some of these approaches are seriously damaging carbon nanotubes (CNTs) such as sidewall opening and breaking. Thus, there have yet been no reports on maximum enhanced properties produced by nanocomposites containing CNT. In this regards, we are attempting various efforts to overcome such issues. One of our continuous devotes on the development of chemical modification method, which should be effective but mild and thus non-destructive via electrophilic substitution reaction, is in polyphosphoric acid (PPA). 4-fluorobenzenesulfonyl chloride could be covalently bonded onto the surface of MWNTs. Direct and uniform functionalization of MWNT could be achieved faster and more effective than carboxylic acid. This may be due to sulfonium ion is more reactive than carbonium ion. The reaction progress was conveniently monitored with FT-IR spectroscopy following the growth of the sulfonyl band. In addition to that, Soxhlet extraction experiment, SEM, TGA, and EA were used to verify covalent attachment onto the surface of MWNTs.