Multiblock Copolymers toward Segmentation-Driven Morphological Transition

Abstract

Conventional methods for controlling self-assembly are generally based on the change in hydrophilic/hydrophobic volume fraction of diblock or triblock copolymers, which suffer from low structural diversity and limited chemical tunability. Inspired by nature, segmented multiblock copolymers (MBCs) offer unparalleled opportunities for engineering of biomimetic nanomaterials with tailored properties. However, the self-assembly of MBCs remains largely unexplored and poorly understood. In this study, we report a segmentation-mediated self-assembly strategy to manipulate the morphology of protein-mimic responsive MBCs by facilely altering the block numbers while holding the amphiphilicity constant. In particular, we found that an increased number of nearly alternating biodegradable poly(ε-caprolactone) and hydrophilic polyethylene glycol segments drives micelle-to-worm-to-vesicle transition. Moreover, the L-cystine residue-enriched interlayer of assemblies enables a depolymerizationinduced morphology reversion, resulting in a redox-hyper-responsive property and ultrafast intracellular drug release. Both experimental and computational results provide a new insight into the self-assembly of macromolecules and propose a convenient approach to the construction of smart nanoassemblies with controlled architectures.

Recent advances on the structure–properties relationship of multiblock copolymers

“…MBCs self‐assemble in various ways forming isotropic micelles, worm‐like objects or vesicles according to the number of blocks . Insets are corresponding structures obtained from dissipative particle dynamics simulations, adapted from Reference [70]…”

“…68 This great variety comes from continuous progress in chemistry, making it possible to modify on-demand the number of segments, their length and the polymers architecture, 69 resulting in a wide range of accessible microstructures. Beyond their applications as bulk materials, it is worth noting that their association with an appropriate solvent can result in astonishing self-assembled structures serving as drug delivers, 70 chameleon-like skin, 15 or spatio-temporal reversible networks. 71 On the other hand, MBCs provide an unique opportunity to investigate more fundamental aspects of polymer physics and biology.…”

Toward Olefin Multiblock Copolymers with Tailored Properties: A Molecular Perspective

“…The problem would become more multidimensional in case of copolymers and/or multiblock macromolecules, where properties of polymers are determined by the concentration and the position of monomers of each type along the blocks and/or copolymer chains. [4,5] Olefin block copolymers (OBCs) are special-purpose polyolefins resulting from chain shuttling copolymerization of ethylene with α-olefins. [6] They exhibit properties of thermoplastics and elastomers due to hard and soft segments incorporated in their microstructure.…”

“…The problem would become more multidimensional in case of copolymers and/or multiblock macromolecules, where properties of polymers are determined by the concentration and the position of monomers of each type along the blocks and/or copolymer chains. [ 4,5 ]…”

Multiblock Copolymers of Norbornene and Cyclododecene: Chain Structure and Properties

“…All the rich variety of properties is based on the ability of block copolymers to self-assemble into different morphologies, in which monomer unit interactions are balanced by their connectivity in polymer chains [ 18 , 19 ]. Being inferior to diblock copolymers in the accuracy and alignment of domain boundaries, multiblocks demonstrate better mechanical properties, biocompatibility, biodegradability, compatibilizing ability, and tendency to form bicontinuous phases for effective ionic and molecular transport [ 20 , 21 , 22 , 23 , 24 , 25 ].…”