Hierarchical Microphase Behaviors of Chiral Block Copolymers under Kinetic and Thermodynamic Control

Abstract

The chiral superstructures in confined space are subtly affected by the complex interplays among various noncovalent interactions, details of which are still inadequately understood. Here, we report the 3D confined assembly of chiral block copolymer of polystyrene-block-poly(D-lactide) and its enantiomer in emulsion droplets, and demonstrate unprecedented successive microphase transformations from single helices to double helices with inverted helicity, and then to twisted cylinders in the constructed colloidal particles. The above hierarchical structure transformations of chiral microphases are kinetically-dependent and can further transform into thermodynamically stable achiral cylinders with saddle-shaped topology upon solvent annealing.The formation and subsequent structure transformations as well as the final degeneration of chiral architectures provide guidance to both understand the chiral evolution at different length scales within spherical confined space and fabricate biomimetic systems.

Chiral transfer‐dictated self‐assembly of chiral block copolymers

“…Furthermore, it evidenced the homochiral transfer from the PLLA/PDLA configuration to the PLLA/PDLA internal helixes*. [183] Not only did these contributions paved a pathway to a controlled confined assembly of BCPs*, it also inspired further investigations on how confinement would impact the morphological chirality of BCP* assemblies.…”

Structure Regulation of Block Copolymer Assemblies in Emulsion Droplets by Adding a Selective Solvent

“…[ 12 ] In the past decade, many studies have been reported on controlling the morphologies of BCP colloidal particles by varying the volume fraction, degree of confinement, solvent selectivity, evaporation dynamics, and interfacial interaction. [ 4,15–25 ]…”

“…[12] In the past decade, many studies have been reported on controlling the morphologies of BCP colloidal particles by varying the volume fraction, degree of confinement, solvent selectivity, evaporation dynamics, and interfacial interaction. [4,[15][16][17][18][19][20][21][22][23][24][25] In emulsion droplets, interfacial selectivity (relative affinity of each block with the continuous phase) determines the segment orientation of BCP and thereby the morphology of the assemblies. [2,26,27] The interfacial selectivity can be adjusted by varying the properties of the surfactants.…”

“…3D confined self-assembly (3D-CSA) of block copolymers (BCPs) that enables the generation of internally ordered colloidal polymer particles with various overall shapes has received increasing attention in the last two decades. [1][2][3][4][5][6][7][8][9] Among various methods, [1,3,10,11] emulsion solvent evaporation-induced 3D-CSA enables the most flexible engineering of the structure of assemblies because of the deformable confinement space and adjustable interface. [2] Typically, a water-insoluble BCP is first DOI: 10.1002/marc.202100845 dissolved in a water-immiscible good solvent to form a solution, which is then emulsified with an aqueous solution containing surfactants to obtain an oil-inwater (O/W) emulsion.…”

Selective synthesis of helical polymers

“…In addition, helical polymers are widely used in many fields such as ferroelectric liquid crystals (LCs), enantiomer separation, asymmetric catalysis and so on 5–10 . Therefore, chemists have made many efforts to design and synthesize plenty of synthetic helical polymers, oligomers and helical assemblies 11–19 …”