Synthesis and properties of polyurethane ionomers based on carboxylated polycaprolactone

Polycaprolactone containing carboxyl groups (CPCL, (M) over bar(n) = 1200) was prepared from caprolactone (CL) and dimethylol propionic acid (DMPA). B ased on the CPCL,4,4,'-diphenylmethane diisocyanate (MDI) and 1,4-butanedio l (BD), a novel series of polyurethane ionomers could be synthesized with i ons in the soft segment. The tensile modulus and ultimate elongation of the ionomer cast films increased, and the glass transition temperature of the CPCL-rich phase moved to a higher temperature after ionization. Moreover, t his kind of ionomers showed small amounts of hard seg ment crystallinity by DSC. WAXD shows an ionic peak at 2 theta = 8.6 degrees for the ionomer wit h carboxylate in the hard segment, which is not present in the ionomer with carboxylate in the soft segment. (C) 2000 John Wiley & Sons, Inc.