Mesh-size control and functionalization of reorganizable chemical gels by monomer insertion into their cross-linking points

Mesh-size control of network structures of chemical gels, i.e. mesh expansion by insertion of styrene derivatives and mesh shrinking by insertion of divinylbenzene in the gels, was carried out. Chemical gels with alkoxyamine at their cross-linking points were synthesized by radical copolymerization of methyl methacrylate and divinyl monomer with alkoxyamine units. The monomers were inserted by heating the gels with each monomer separately, and the network size was evaluated by small-angle X-ray scattering (SAXS) measurements. Since a living polymerization procedure was adopted for the reactions, network mesh sizes were controlled precisely by controlling the reaction time and selecting an appropriate monomer. In addition, gel properties such as swelling degree and phase separation could also be controlled by employing functional monomers such as hydrophilic and fluorinated monomers. These reorganizable chemical gels combine the advantages of high stability of chemical gels with ease of structural changeability of physical gels.