Synthesis and Properties of Polyurethane Crosslinked by Polyrotaxane Consisting of Monoaminocyclodextrin

Abstract

A polyurethane (PU) crosslinked by a polyrotaxane (PRX), which consists of monoamino-α-cyclodextrin(amCyD) and poly(ethylene glycol)4000 (PEG4000), was designed to decrease the formation of multiple crosslinks from one CyD. The capping reaction of the pseudo-PRX containing amCyD was achieved by a click reaction. The filling ratio of amCyD in the PRX was ca. 74%. The PU crosslinked by the PRX(PU-PRXam(74)) was prepared by a prepolymer method. The thermal and physical properties of PU-PRXam(74) were compared with those of the PUs crosslinked by PRXs consisting of half-methylated CyD(PU-PRXMe(43) and PU-PRXMe(63)). The degree of swelling of PU-PRX-am(74) was ca. 1.3 times larger than those of PU-PRXMes, suggesting the decrease in the multiple crosslinks from one CyD. The DSC and dynamic viscoelastic measurements revealed that PU-PRXam(74) shows a unique relaxation after its glass transition. In the tensile test results, PU-PRXam(74) showed the best elongation among the PU-PRXs whereas the tensile strength was lower than the others. This result is also evidence of the decrease in the multiple crosslinks from one CyD.