More Like this

1. Controlling Size and Surface Chemistry of Cationic Nanogels by Inverse Microemulsion ATRP

   https://doi.org/10.1002/macp.202200210  

   Simakova, Antonina; Averick, Saadyah; Jazani, Arman Moini; Matyjaszewski, Krzysztof (August 2022, Macromolecular Chemistry and Physics)

   Abstract The unique properties of cationic nanogels, such as their hydrophilicity and high loading capacity, make them a promising platform as drug delivery agents, particularly for the delivery of hydrophilic biomolecules. Although several synthetic methods exist for cationic nanogels, polymerization in dispersed media is advantageous due to its ability to provide control over composition and high monomer conversion. However, polymer droplets typically suffer from a significant increase in size during polymerization due to the Ostwald ripening process. Herein, the preparation of cationic nanogels by atom transfer radical polymerization under inverse microemulsion conditions of a hydrophilic inimer that prevents monomer diffusion and hence limits droplets’ growth during polymerization is reported. Additionally, the surface functionality of the nanogels can be modulated by the application of hydrophobic reactive surfactants or by grafting hydrophilic shells to form core‐shell cationic nanogels. The synthesized cationic nanogels are biocompatible, internalized to HEK 293 cells, and have a high complexation ability for plasmid DNA. 

   more » « less
2. Facile Fabrication Technique of Polymeric Ionic Liquids‐Coated Core–Shell Nanoparticles for Polymer Electrolyte Membranes

   https://doi.org/10.1002/adsu.202300395  

   Tabata, Keisuke; Makino, Tsutomu; Matsuo, Yoshimasa; Sinkus, Rose; Masuhara, Akito (December 2023, Advanced Sustainable Systems)

   Abstract Nanoparticles and nanofibers are widely used as components of polymer electrolytes for membranes in fuel cells, and many surface modification methods are reported. However, some fabrication techniques are complicated, and it is necessary to develop a simplified and precise control method. Herein, a facile fabrication method is reported for core–shell nanoparticles hierarchically coated with polymeric ionic liquids (PIL) and hydrophobic polymers as a material for polymer electrolytes. A hierarchical polymer layer on the surface of the SiO₂nanoparticles is easily constructed by repeating the facile polymer‐coating technique based on precipitation polymerization several times. The highest proton conductivity of the core–shell nanoparticles is 1.3 × 10⁻² S cm⁻¹at 80 °C and 95% relative humidity. Although the hydrophobic polymers coated as a protective layer reduce the proton conductivity, the formation of the PIL enhances the proton conductivity in various temperature and humidity environments. Therefore, the proposed method enables the facile fabrication of polymer layers with multiple functions, such as a proton‐conductive PIL layer and hydrophobic polymer layers as protective layers on the surface of the nanoparticles. Furthermore, they are expected to be applied to energy supply and gas separation, including polyelectrolytes, for the realization of a sustainable society. 

   more » « less
3. Polymers on nanoparticles: structure & dynamics

   https://doi.org/10.1039/C8SM02110D  

   Hore, Michael J. (February 2019, Soft Matter)

   Grafting polymers to nanoparticle surfaces influences properties from the conformation of the polymer chains to the dispersion and assembly of nanoparticles within a polymeric material. Recently, a small body of work has begun to address the question of how grafting polymers to a nanoparticle surface impacts chain dynamics, and the resulting physical properties of a material. This Review discusses recent work that characterizes the structure and dynamics of polymers that are grafted to nanoparticles and opportunities for future research. Starting from the case of a single polymer chain attached to a nanoparticle core, this Review follows the structure of the chains as grafting density increases, and how this structure slows relaxation of polymer chains and affects macroscopic material properties. 

   more » « less
4. Modeling Solution Drying by Moving a Liquid-Vapor Interface: Method and Applications

   https://doi.org/10.3390/polym14193996  

   Tang, Yanfei; McLaughlan, John E.; Grest, Gary S.; Cheng, Shengfeng (October 2022, Polymers)

   A method of simulating the drying process of a soft matter solution with an implicit solvent model by moving the liquid-vapor interface is applied to various solution films and droplets. For a solution of a polymer and nanoparticles, we observe “polymer-on-top” stratification, similar to that found previously with an explicit solvent model. Furthermore, “polymer-on-top” is found even when the nanoparticle size is smaller than the radius of gyration of the polymer chains. For a suspension droplet of a bidisperse mixture of nanoparticles, we show that core-shell clusters of nanoparticles can be obtained via the “small-on-outside” stratification mechanism at fast evaporation rates. “Large-on-outside” stratification and uniform particle distribution are also observed when the evaporation rate is reduced. Polymeric particles with various morphologies, including Janus spheres, core-shell particles, and patchy particles, are produced from drying droplets of polymer solutions by combining fast evaporation with a controlled interaction between the polymers and the liquid-vapor interface. Our results validate the applicability of the moving interface method to a wide range of drying systems. The limitations of the method are pointed out and cautions are provided to potential practitioners on cases where the method might fail. 

   more » « less
5. Beyond simple self-healing: How anisotropic nanogels adapt their shape to their environment

   https://doi.org/10.1063/5.0119527  

   Nickel, Anne C.; Denton, Alan R.; Houston, Judith E.; Schweins, Ralf; Plivelic, Tomàs S.; Richtering, Walter; Scotti, Andrea (November 2022, The Journal of Chemical Physics)

   The response of soft colloids to crowding depends sensitively on the particles’ compressibility. Nanogel suspensions provide model systems that are often studied to better understand the properties of soft materials and complex fluids from the formation of colloidal crystals to the flow of viruses, blood, or platelet cells in the body. Large spherical nanogels, when embedded in a matrix of smaller nanogels, have the unique ability to spontaneously deswell to match their size to that of the nanogel composing the matrix. In contrast to hard colloids, this self-healing mechanism allows for crystal formation without giving rise to point defects or dislocations. Here, we show that anisotropic ellipsoidal nanogels adapt both their size and their shape depending on the nature of the particles composing the matrix in which they are embedded. Using small-angle neutron scattering with contrast variation, we show that ellipsoidal nanogels become spherical when embedded in a matrix of spherical nanogels. In contrast, the anisotropy of the ellipsoid is enhanced when they are embedded in a matrix of anisotropic nanogels. Our experimental data are supported by Monte Carlo simulations that reproduce the trend of decreasing aspect ratio of ellipsoidal nanogels with increasing crowding by a matrix of spherical nanogels. 

   more » « less