Intermolecular complexation between PEG/PBT block copolymer and polyelectrolytes polyacrylic acid and maleic acid copolymer

The intermolecular complexation (IPC) between PEG!PBT copolymer and polyelectrolytes such as polyacrylic acid (PAA) and ethylene-co-maleic acid (EMa) copolymer was studied by means of DSC. TGA and IR. The study results indicated that the PEG segment which had a molecular weight of 1000 D still had the ability to form IPC with PAA or EMa at lower pH due to the presence of a PET segment. The presence of the PET segment stabilized the IPC through hydrophobic or dipole interaction between PET and PAA or EMa. At slightly basic pH, interaction between PEG and PAA or EMa was also observed, but the interaction was attributed to dipole interaction. These findings indicated that it is possible to modify the bulk properties of PEG-based block copolymers by forming an IPC with polyacid. (C) 1997 Elsevier Science Ltd.