Engineering the Morphologies of Block Copolymer Particles from the Confined Self-assembly within Emulsion Droplets

Block copolymers(BCPs)can automatically assemble into various regulated nanoparticles when they are confined within the emulsion droplet be-cause of the structural frustration of polymer chains and the soft template effect of the oil/water interface.In the past few years,great efforts have been made to regulate the morphologies of the resulting BCP particles.In this review article,various strategies for tuning oil/water interfacial prop-erties to engineer the as-formed BCP particles were summarized.Then,the comprehensive scenarios of the applications of the resulting BCP parti-cles were discussed.Finally,the future tendency and challenge of the self-assembly of BCPs confined in emulsion droplet were suggested.

Fabrication of Polymersomes with Controllable Morphologies through Dewetting w/o/w Double Emulsion Droplets

In this work, monodisperse giant polymersomes are fabricated by dewetting of water-in-oil-in-water double emulsion droplets which are assembled by amphiphilic block copolymer molecules in a microfluidic device. The dewetting process can be tuned by solvation between solvent and amphiphilic block copolymer to get polymersomes with controllable morphology. Good solvent （chloroform and toluene） hinders dewetting process of double emulsion droplets and gets acornlike polymersomes or patched polymersomes. On the other hand, poor solvent （hexane） accelerates the dewetting process and achieves complete separation of inner water phase from oil phase to form complete bilayer polymersomes. In addition, twin polymersomes with bilayer membrane structure are formed by this facile method. The formation mechanism for different polymersomes is discussed in detail.

Double Emulsion Droplets as Microreactors for Synthesis of Magnetic Macroporous Polymer Beads

An easy method is presented to fabricate monodisperse magnetic macroporous polymer beads（MMPBs）. Waterin-oil high internal phase emulsion（HIPE） is prepared by emulsifying aqueous iron ions solution in an oil phase containing monomers. The HIPE is introduced into a simple microfluidic device to fabricate monodisperse（water-in-oil）-in-water double emulsion droplets. The droplets serve as microreactors to synthesize Fe3O4 nanoparticles and are on-line polymerized to form MMPBs. The prepared MMPBs display uniform size, interconnected porous structure, superparamagnetic behavior and uniform distribution of Fe3O4 in polymer matrix. The MMPBs are characterized by scanning electron microscopy（SEM）, Fourier transform infrared spectroscopy（FTIR）, X-ray diffraction（XRD）, transmission electron microscopy（TEM）, vibrating sample magnetometry（VSM）. We believe that this method is a universal technique in preparing macroporous nanocomposite beads.

Hydrodynamic cavitation as an efficient method for the formation of sub-100 nm O/W emulsions with high stability

Hydrodynamic cavitation,a newly developed process intensification technique,has demonstrated immense potential for intensifying diverse physical and chemical processes.In this study,hydrodynamic cavitation was explored as an efficient method for the formation of sub-100 nm oil-in-water(O/W) emulsions with high stability.O/W emulsion with an average droplet size of 27 nm was successfully prepared.The average droplet size of O/W emulsions decreased with the increase of the inlet pressure,number of cavitation passes and surfactant concentration.The formed emulsion exhibited admirable physical stability during 8 months.Moreover,the hydrodynamic cavitation method can be generalized to fabricate large varieties of O/W emulsions,which showed great potential for large-scale formation of O/W emulsions with lower energy consumption.

Mesoscale regulation of droplet templates to tailor microparticle structures and functions

The hierarchical design of mesoscale structures in droplet templates determines the structure and functionality of the resultant microparticles.In this review,we summarize recent progress on the control of microfluidic emulsion templates for the synthesis of polymeric microparticles with desired functionality and internal structure.We introduce strategies for controlling the morphology and interfacial stability of emulsion templates.These strategies are based on manipulation of the mesoscale structure of amphiphilic molecules and nanoparticles at emulsion-droplet interfaces.We also discuss strategies for controlling the mesoscale structure of microparticles,which involve manipulating the interfacial mass-transfer and chemical reactions during template synthesis.We provide insight on the use of these strategies for the rational design and fabrication of polymeric microparticles with predictable internal structures and functionality at the single-particle level.