Abstract
This review article mainly summarized the research works on development of novel supramolecular polymers, poly [3] rotaxane and polyrotaxane gel. The chemistries of interlocked molecules such as rotaxane and catenane were discussed, prior to the research works, with emphasis on their structural feature and applicability. The synthetic methods of rotaxanes were categorized and each method was discussed in terms of the characteristics. A new synthetic method of rotaxanes, as a basis of the syntheses of poly [3] rotaxane and polyrotaxane gel, was developed by applying the thiol-disulfide exchange reaction to a mixture of a dumbbell disulfide and a crown ether wheel. In this method, [2] rotaxane and [3] rotaxane was obtained in ca. 90% yields. Since the thiol-disulfide exchange reaction was an equilibrium reaction, the formation of the rotaxanes could be controlled by temperature, concentration, and so on. The reaction was extended to use of homoditopic crown ether to obtainpoly [3] rotaxane of which molecular weight was 20000-60000, via polyslipping. The use of poly (crown ether) instead of monofunctional crown ether caused the formation of gelled product in a quantitative yield. The gelled material was swollen with polar organic solvents such as DMF and DMSO to give transparent elastic gel. By utilizing the equilibrium nature of this system, the gelled polymer as crosslinked polymer was subjected to the evaluation of recyclability. As a result, the gelled polymer became a homogeneous solution containing the starting materials when it was treated with a thiol in DMF at 70°C, suggesting its high recyclability.
