Confined Self-Assembly of Block Copolymers within Emulsion Droplets: A Perspective

When the self-assembly of block copolymers (BCPs) occurs within organic emulsion droplets in the aqueous phase, the strong structural frustration of BCP chains causes the formation of a series of well-regulated BCP particles that cannot be obtained from the self-assembly of BCPs in the bulk state or solution. In this Perspective, we review the recent progress of the self-assembly of BCPs confined in emulsion droplets. The governing factors of the structure and morphology of the as-prepared BCP particles are summarized. In addition, the applications of the as-prepared BCP particles in photonic crystals and drug release are discussed. Finally, we also give a forward-looking perspective on future challenges in this field.

Hybridization of Poly(oxazoline) and Poly(ethylene oxide)-Based Amphiphilic Copolymers into Thermosensitive Mixed Micelles of Tunable Cloud Point

This paper reports the development in aqueous solution of mixed micelles of tunable cloud point temperature through blending in various proportions of two copolymers of different chemical natures. For that purpose, a lipid-b-poly(2-isopropyl-2-oxazoline) (lipid-b-P(iPrOx)) copolymer, self-assembling into thermosensitive micelles that phase-separate above a cloud point temperature of 38 °C, was blended in various proportions with commercial C₁₈-b-PEO_x. The latter was constituted of a hydrophobic saturated C₁₈ chain and a hydrophilic poly(ethylene oxide) (PEO) block with varying polymerization degrees (x) and does not have any thermosensitive properties on the studied temperature range for any value of x. The different blends were thoroughly characterized by light scattering and UV-visible spectroscopy, revealing that hybridization between both copolymers always occurred, independent of the PEO block length. The resulting mixed micelles present T_CP values progressively increasing with the C₁₈-b-PEO_x proportion, from 38 to 61 °C. This study demonstrates the relevance of the blending approach to tune the phase separation of micellar systems by formulation rather than by more tedious synthetic efforts. Shifting T_CP through this approach extends the range of temperature where lipid-b-P(iPrOx) can find an application.

Anisotropic polymer nanoparticles with controlled dimensions from the morphological transformation of isotropic seeds

Understanding and controlling self-assembly processes at multiple length scales is vital if we are to design and create advanced materials. In particular, our ability to organise matter on the nanoscale has advanced considerably, but still lags far behind our skill in manipulating individual molecules. New tools allowing controlled nanoscale assembly are sorely needed, as well as the physical understanding of how they work. Here, we report such a method for the production of highly anisotropic nanoparticles with controlled dimensions based on a morphological transformation process (MORPH, for short) driven by the formation of supramolecular bonds. We present a minimal physical model for MORPH that suggests a general mechanism which is potentially applicable to a large number of polymer/nanoparticle systems. We envision MORPH becoming a valuable tool for controlling nanoscale self-assembly, and for the production of functional nanostructures for diverse applications.

Confined co-assembly of AB/BC diblock copolymer blends under 3D soft confinement

Compared to synthesizing a new block copolymer, blending of two types of block copolymers or a block copolymer and a homopolymer is a simple yet effective approach to create new self-assembled nanostructures. Here, we apply Monte Carlo (MC) simulations to mimic the co-assembly of AB/BC diblock copolymer blends within a three-dimensional (3D) soft confined space, which corresponds to the co-assembly confined in an emulsion droplet in experiment. The confined co-assemblies of four types of block copolymer blends at different block ratios, i.e., A8B8/B8C8, A6B10/B10C6, A12B4/B4C12 and A12B4/B10C6, are investigated by MC simulations. The simulation results reveal that the ratio of different types of blocks and the polymer-solvent interactions between the different blocks and the solvent determine the final self-assembled nanostructures. By tailoring these two controlling parameters, we not only reproduced some classic nanostructures, i.e., pupa-, onion-, and bud-like particles, but also predicted some unconventional nanostructures, such as patch-, Janus-, peanut-, disc- and snowman-like particles via MC simulations.

Recent progress in the self-assembly of block copolymers confined in emulsion droplets

When the self-assembly of block copolymers (BCPs) occurs within a deformable emulsion droplet, BCPs can aggregate into a variety of nanoscaled particles with unique nanostructures and properties since the confinement effect can effectively break the symmetry of a structure.

Redox-Responsive Multicompartment Vesicles of Ferrocene-Containing Triblock Terpolymer Exhibiting On-Off Switchable Pores

Multicompartment vesicles of ferrocene-containing triblock terpolymer containing on-off switchable pores in the vesicular membrane are prepared by seeded RAFT polymerization. In these multicompartment vesicles, the incompatible solvophobic poly(4-vinylbenzyl ferrocenecarboxylate) (PVFC) and poly(benzyl methacrylate) (PBzMA) blocks form the porous phase-segregated membrane and the solvophilic poly[2-(dimethylamino) ethyl methacrylate] block locates at the inner and outer sides of the membrane. These porous multicompartment vesicles are redox-responsive and the membrane pores can be on-off switched through redox triggering. These porous multicompartment vesicles are deemed to be new nanoassembly of ABC triblock terpolymer and are anticipated to be a smart host to load and release guests.