Polymethylene-b-poly(acrylic acid) diblock copolymers: Morphology and crystallization evolution influenced by polyethyene polyamine with dual confinement effects

Abstract

In this work, we systematically investigated the aggregation and confined crystallization behavior of polymethylene-b-poly acrylic acid diblock copolymers (PM-b-PAA, M93A94) under the influence of polyethyene polyamine (PPA). With the increasing molar ratio of PPA, the morphologies of PM-b-PAA micelles experienced sphere-to-band-to-sheet transformations with regular changes of sizes on cooling from 80 °C mixed solution. Further investigation of the crystalline feature of PM-b-PAA indicated that the crystallization of PM block was profoundly restrained by PPA with the dual confinements, i.e., chemical and physical confinement which exerted through the hierarchical hydrogen bonding and 3D hydrogel network, respectively, in the mixed system. In particular, when the PPA and PM-b-PAA aqueous solution were mixed with equivalent volume, hydrogels was accessible. And rheology property indicated that the BCP/PPA-0.5 hydrogels hold the maximal storage modulus G′, and meanwhile the minimum loss tangent, tanδ.