Noncovalent Supramolecular Diblock Copolymers: Synthesis and Microphase Separation

Supramolecular block copolymers (PS-DAT-) were synthesized via noncovalent hydrogen bonding between well-defined thymine end-functionalized polyisoprene (PI-Thy) and diaminotriazine (DAT) end-functionalized polystyrene (PS-DAT). Three covalently linked block copolymers were also synthesized for comparison with the noncovalent supramolecular block copolymers. The complementary DAT/Thy interaction resulted in the microphase separation of the supramolecular block copolymer system. Detailed characterization of all functionalized homopolymers and block copolymers was carried out via proton nuclear magnetic resonance (¹H NMR) spectroscopy, gel permeation chromatography, matrix-assisted laser desorption/ionization-time of flight mass spectrometry, and differential scanning calorimetry. The self-assembly process of supramolecular block copolymers was evidenced by transmission electron microscopy. Small-angle X-ray scattering was also performed to study the microphase separation of supramolecular and covalently linked block copolymers. Comparison of microphase separation images of supramolecular block copolymers and the corresponding covalently linked analogues reveals differences in d-spacing and microdomain shape.