화학공학소재연구정보센터
Macromolecules, Vol.53, No.11, 4214-4223, 2020
Kinetically Dependent Self-Assembly of Chiral Block Copolymers under 3D Confinement
Self-assembly of chiral block copolymers (BCPs*) has attracted myriad attention due to their intriguing abilities to form chiral structures and potential applications in chiral adsorption, chiral separation, and others. Yet, efforts to tailor their assembly structures were usually challenged by the intricate assembly behavior of BCPs*. Herein, we systematically examined the kinetically dependent assembly behavior of polystyrene-block-poly(D-lactide) (PS-b-PDLA) BCPs* under three-dimensional (3D) confinement in emulsion droplets. By decreasing the solvent evaporation rate, an irreversible morphological evolution of BCP* particles was observed, from rough spheres with an internal helical structure (morphology I) to first honey dipper-like ellipsoids with a parallelly striped surface pattern and an internal loop-like cylindrical structure (morphology II) and thereafter to smooth spheres with an internal network structure (morphology III). Moreover, such a kinetically dependent morphological evolution was impacted by solvent affinity. By implementing thermal and solvent-absorption annealing, irreversible transitions of morphology I -> III and II -> III were realized, affirming that morphology III is an equilibrium state, while morphology I and II are kinetically trapped metastable counterparts. After the selective removal of PDLA by hydrolysis, various mesoporous channels were generated in the BCP* particles. This finding of the kinetically dependent assembly of BCPs* under 3D confinement not only contributed to interpreting the unique assembly behavior of BCPs* but also inspired prospects for applications in preparing chiral mesoporous particles, chiral separation, controlled drug release, and others.