US Patent 7943718 Hydrophobic modified polyrotaxane and crosslinked polyrotaxane

To provide a hydrophobic modified polyrotaxane soluble in an organic solvent, and a crosslinked polyrotaxane using this. A hydrophobic modified polyrotaxane has a cyclic molecule, a linear molecule including the cyclic molecule with piercing through the cyclic molecule, and blocking groups which are placed at both end terminals of the linear molecule to prevent the cyclic molecule from leaving from the linear molecule. The cyclic molecule is cyclodextrin, and each of all or a part of the hydroxyl groups in the cyclodextrin is modified with a hydrophobic modification group.