Effect of Shear Flow on the Formation of Ring-Shaped ABA Amphiphilic Triblock Copolymer Micelles

Abstract

We have investigated the effect of shear flow on the formation of ring-shaped ABA triblock copolymer (P4VP 43 -b-PS 260 -b-P4VP 43 ) micelles. The results reveal that shear flow plays an important role in the formation of the rings. Both ring size and its distribution are found to be dependent sensitively on the stirring rate. Sizable rings are more likely to be formed at moderate stirring rate. Interestingly, the ring formation mechanism is also dependent on the shear flow. Copolymers are likely to form rings via end-to-end cylinder connection at low stirring rates, whereas they tend to form rings via the pathway of the rod-sphere-vesicle-ring at high stirring rates.

Shear Induced Morphological Transformation of Large Compound Micelles Formed by Glutathione End‐capped Poly(4‐vinylpyridine)

“…Only in a few cases shear-induced morpho-logical transitions were observed. [16,[22][23][24] In the present study, we found that the GP4VP LCMs are very sensitive to shear force. Under the shear flow generated by the spindly stir bar at the rate of 1500 r/min, the morphology of GP4VP 75 aggregates changes remarkably, as exhibited by the differences between the morphologies at different stir time.…”

“…[10][11][12][13][14][15] Usually, the smart assemblies are responsive to pH, temperature, light, magnetic field and so on. Compared to those conventional smart assemblies, shear-responsive ones are newly emerged [16] and have attracted more and more attention as they could be used as carriers for drug delivery in biological systems and other circumstances where shear force exists. It is noted that shear can not only lead to the structural changes that can be used for practical applications, but also produce new morphologies inaccessible via conventional self-assembly processes.…”

Preparation of Mesoporous 1,4‐Phenylene‐silica Nanorings through a Dual‐templating Approach

“…It was reported recently that shear flow can induce ABA triblock copolymers to organize into nanorings. [27] At a low stirring rate, the rings are formed via end-to-end cylinder connection. However, the rings are formed via the pathway of the rod-sphere-vesiclering at high stirring rate.…”

“…It was reported previously that block copolymers can self-assemble into nanorings in solvents by changing the volume ratios of hydrophobic/hydrophilic chains [26] or stirring speed. [27] Herein, to obtained mesoporous 1,4-phenylene-silica nanorings, commercial cetyltrimethylammonium bromide (CTAB) and (S)-2-methyl-1-butanol were used as the template and the co-structure-directing agent, respectively. according to literature.…”

Fabrication of Active Surfaces with Metastable Microgel Layers Formed during Breath Figure Templating

“…15 Routes to APPS include physical or chemical modification of surfaces. Physical methods normally include procedures involving electrical fields, [16][17][18][19] self-assembly of nanoparticles, [20][21][22][23][24][25] interfacial instabilities, [26][27][28][29][30] soft lithography, [31][32][33][34] etc. On the other hand, chemical approaches are mainly achieved by chemically grafting responsive self-assembled monolayers (SAMs) or polymer brushes onto surfaces to obtain responsive wettability and conductivity, etc.…”