Complex formation between poly(oxytrimethylene) and cyclodextrins

Poly(oxytrimethylene) (POT) has been found to form inclusion complexes with cyclodextrins to give crystalline compounds in high yields. The yields of the complexes of POT with α‐cyclodextrin increased with increase in the molecular weight of POT, reached a maximum at a molecular weight of about 1000, and then decreased with the molecular weight. The stoichiometries are 1:1.5‐2 (CD:monomer unit) when the molecular weight of POT is less than 2000. β‐Cyclodextrin gave complexes with POT in a 1:2‐2.5 ratio when the average molecular weights were less than 2000. When the molecular weight of the polymer was higher than 3000, the ratio of the monomer unit to cyclodextrin increased with increase in the molecular weight. The binding modes are discussed.