Phenylboronate-diol crosslinked polymer/SWCNT hybrid gels with reversible sol-gel transition

This work demonstrates the successful incorporation of functionalized single-walled carbon nanotubes (f-SWCNTs) into the phenylboronate-diol crosslinked polymer gel to create a hybrid system with reversible sol-gel transition. The phenylboronic acid-containing and diol-containing polymers were first separately prepared by the reversible addition-fragmentation chain transfer polymerization. Covalent functionalization of single-walled carbon nanotubes (SWCNTs) with an azide-derivatized, diol-containing polymer was then accomplished by a nitrene addition reaction. Subsequently, the hybrid gels were prepared by crosslinking the mixture of f-SWCNTs and diol-containing polymer with the phenylboronic acid-containing polymer. The hybrid gel has been characterized by scanning electron microscopy (SEM) and rheological analysis. The SEM measurement demonstrated a homogeneous dispersion of f-SWCNTs within the gel matrices. Rheological experiments also demonstrated that the hybrid gel exhibited storage moduli significantly higher than those of the native gel obtained from the phenylboronic acid-containing and diol-containing polymers. The hybrid gel can be switched into their starting polymer (f-SWCNTs) solutions by adjusting the pH of the system. Moreover, the hybrid gel revealed a self-healing property that occurred autonomously without any outside intervention. By employing this dynamic character, it is possible to regenerate the used gel, and thus, it has the potential to perform in a range of dynamic or bioresponsive applications Copyright (c) 2013 John Wiley & Sons, Ltd.