Pickering emulsions are water or oil droplets that are stabilized by colloidal particles and have been intensely studied since the late 90s. The surfactant-free nature of these emulsions has little adverse effects such as irritancy and contamination of environment and typically exhibit enhanced stability compared to surfactant-stabilized emulsions. Therefore, they offer promising applications in cosmetics, food science, controlled release, and the manufacturing of microcapsules and porous materials. The wettability of the colloidal particles is the main parameter determining the formation and stability of Pickering emulsions. Tailoring the wettability by surface chemistry or surface roughness offers considerable scope for the design of a variety of hybrid nanoparticles that may serve as novel efficient Pickering emulsion stabilizers. In this review, we will discuss the recent advances in the development of surface modification of nanoparticles.
Environmentally responsive cotton fabrics were fabricated by dip-coating ABC miktoarm star terpolymers, which contain reactive poly(3-triisopropyloxysilylpropyl methacrylate) blocks, hydrophobic poly(dimethylsiloxane) (PDMS) blocks, and hydrophilic poly( N , N -dimethylaminoethyl methacrylate) (PDMAEMA) blocks. The functionalized cotton fabrics with perfectly alternating PDMS and PDMAEMA blocks show underoil superhydrophobicity and underwater superoleophobicity. The wettability and permeability of the functionalized fabrics can be readily adjusted by the contacting medium. More interestingly, surface reconstruction causes a reduction in the breakthrough pressure of the nonwetting phase. The adaptive permeability endows the functionalized cotton fabrics with the capability to separate heavy oil–water–light oil ternary mixtures.
In this work, we have investigated the effect of laminar flow shearing on the formation of block copolymer agglomerates in viscous medium. Under a laminar flow shearing, the block copolymer solution droplets were spontaneously emulsified and were then elongated into protofibers, which in turn transformed into particles with various morphologies. Besides micro-/nanorods, which were previously reported for homopolymers, sphere and sheetlike structures were unexpectedly fabricated from block copolymers depending on the solvent quality, solvent exchange rates, and the entanglement of the polymer chains. In particular, the sheet structure, fabricated from poly(ethylene glycol)-b-polystyrene (PEG-b-PS), can be fixed by UV irradiation when photo-crosslinkable azide groups were introduced onto the polystyrene block. Surprisingly, we found that the fixed sheetlike structures show demulsification capability in tens of seconds, which may have great potential application in the separation of oil from emulsions.
The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/macp.201800189. Biodegradable PolymersThe hybrid copolymerization of vinyl monomers with cyclic esters endows the formed copolymers new features, such as biodegradability and functionality. However, the recently reported hybrid copolymerizations are mainly based on polar vinyl monomers and cyclic esters catalyzed by organocatalysts. The copolymerization of non-polar vinyl monomers with cyclic esters is still a challenge. In this work, the copolymerization of β-butyrolactone (β-BL) with styrene catalyzed by B(C 6 F 5 ) 3 in the absence of coinitiators is reported. The density functional theory studies suggest the formation of zwitterion between β-BL and B(C 6 F 5 ) 3 . It is found that β-BL and styrene are concurrently copolymerized through the macro-zwitterion intermediates. The obtained copolymers are carefully examined by 1 H NMR, 2D 1 H-13 C HMBC, differential scanning calorimetry, thermogravimetric analysis, hydrolysis experiments, as well as Brady's reagents.
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