Polymer vesicle sensor through the self-assembly of hyperbranched polymeric ionic liquids for the detection of SO2 derivatives

A novel thermoresponsive hyperbranched multiarm copolymer with a hydrophobic hyperbranched poly[3-ethyl-3-(hydroxymethyl)oxetane] core and many poly(acrylamide- co-acrylonitrile) (P(AAm- co-AN)) arms was for the first time synthesized through a reversible addition-fragmentation chain-transfer polymerization. These copolymers show reversible, sharp, and controlled temperature-responsive phase transitions at the upper critical solution temperature (UCST) in water and electrolyte solution. It is the first report on the hyperbranched copolymers with a UCST transition. Two series copolymers with variable AN content (series A) and variable arm length (series B) were synthesized to study the influence of molecular structure on the UCST transition. It was found that the UCST of copolymers could be raised by increasing the AN content or decreasing the arm length. Most interestingly, the amplification effect of the hyperbranched topological structure leads to a broad change of the UCST from 33.2 to 65.2 °C with the little change of AN content (5.9%). On the basis of variable temperature nuclear magnetic resonance, dynamic light scattering, and transmission electron microscopy, a UCST transition mechanism, in combination with hydrophilic/hydrophobic balance and multimicelle aggregate (MMA), was proposed. This work enriches the UCST copolymer topology and may extend the knowledge on the structure-activity relationship as well as the mechanism of the UCST polymers.

Section: Introductionmentioning

confidence: 97%

Hyperbranched Multiarm Copolymers with a UCST Phase Transition: Topological Effect and the Mechanism

Zheng

et al. 2018

“…For mesoscopic simulations of macromolecular morphological expressions, dissipative particle dynamics (DPD) simulation is currently the most popular simulation method for relevant length and time scales. It has been successfully applied to study the self-assembly of macromolecules, such as the self-assembly of vesicles, − micelles, − and nanotubes , and the morphology transition of aggregates. ,, For example, Yamamoto and Hyodo studied the dynamic behavior of two-component vesicles . Li and co-workers investigated the dynamic process of amphiphilic diblock copolymer vesicles .…”

Section: Introductionmentioning

confidence: 99%

“…Sheng and co-workers investigated multilayered polymersomes formed by amphiphilic asymmetric macromolecular brushes . Our group revealed that amphiphilic hyperbranched polymers could self-assemble into vesicles through the bending of a membrane. ,− These successful studies indicate that DPD simulation is a very promising method of investigating the self-assembly behaviors of amphiphilic polymers.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Polymersomes from an Oil-in-Oil Emulsion: A Computer Simulation Study

Zhang

et al. 2017

Asymmetric vesicles are valuable for understanding and mimicking cell and practical biomedicine applications. Recently, a very straightforward methodology for fabricating asymmetric polymersome was developed by Lodge's group through the coassembly of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) and polybutadiene-b-poly(ethylene oxide) (PB-b-PEO) block copolymers at the interface of a polystyrene/polybutadiene/chloroform (PS/PB/CHCl) emulsion. However, the in-depth microscopic mechanism for the formation of asymmetric polymersomes remains unclear. To address this issue, in this article, the coassembly process for the formation of the asymmetric polymersomes in Asano's experimental system was systematically investigated by employing a dissipative particle dynamics (DPD) simulation. Our results definitely demonstrate the formation of the asymmetric polymersomes such as that in the experiments and that the bilayer formed through the folding and crossing of the PEO blocks. Besides, from the microscopic view, three stages can be discerned in the formation process: (1) the formation of micelles, (2) the micelle diffusion to the interface, and (3) the micelle rearrangement at the interface to form an asymmetric polymersome. Meanwhile, the incompatibility among PS, PB, and PEO is proven to be the main driving force for asymmetric polymersome formation. Moreover, the effects of the order of addition of copolymers and the volume fraction of PEO blocks on the structure of the asymmetric polymersomes are also investigated. We find that the formation process is affected severely by the order of addition, and adding PS-b-PEO first can make the asymmetric bilayer more perfect. Not only that, but perfect asymmetric polymersomes can be formed only when the volume fraction of PEO (f) is greater than 0.55. We believe the present work can extend the knowledge of the self-assembly of asymmetric polymersomes, especially with respect to the self-assembly mechanism.

“…Generally, liposomes self-assembled from phospholipids and polymersomes self-assembled from amphiphilic block copolymers are conventional model vesicles. Similar to human red blood cells, vesicles have shown a rich variety of shapes or shape changes in both experimental and theoretical simulation studies. ,− For example, Michalet et al observed equilibrium shapes of topological genus-2 (shapes with two holes) liposomes, which were found to be in agreement with theoretical predictions on the basis of a minimization of the elastic curvature energy for fluid membranes . Markvoort et al studied the liposome deformations on osmotic deflation using coarse-grained molecular dynamics simulations, and prolate ellipsoid, pear-shaped, and budded vesicles were formed by changing the pH or ion concentration .…”

Section: Introductionmentioning

confidence: 92%

Shape Transformations of Vesicles Self-Assembled from Amphiphilic Hyperbranched Multiarm Copolymers via Simulation

Tan

et al. 2018

The understanding of shape transformations of vesicles is of fundamental importance in biological and clinical sciences. Hyperbranched polymer vesicles (branched polymersomes) are newly emerging polymer vesicles with special structure and property. They have also been regarded as a good model for biomembranes. However, the shape transformations of hyperbranched polymer vesicles have not been studied from either an experimental or theoretical level. Herein, the shape transformations of vesicles self-assembled from amphiphilic hyperbranched multiarm copolymers (HMCs) in response to the interaction parameters between the hydrophobic core and hydrophilic arms and the polymer concentrations are investigated carefully through dissipative particle dynamics (DPD) simulations. In the morphological phase diagram, two types of vesicles are obtained: one type corresponds to vesicles without holes formed at low concentrations including unilamellar vesicles, double-lamellar vesicles, discocyte-shaped vesicles, and tubular vesicles, and the other type corresponds to vesicles with holes formed at high concentrations including stomatocyte-shaped vesicles, toroidal vesicles, genus-3 (G-3) toroidal vesicles with three holes, and genus-4 (G-4) toroidal vesicles with four holes. In addition, both the self-assembly mechanisms and the dynamics for the formation of these vesicles have been systematically studied. The current work will offer theoretical support for fabricating novel vesicles with various shapes from hyperbranched polymers.