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16 pages, 2674 KiB

Open AccessArticle

A Polyelectrolyte Colloidal Brush Based on Cellulose: Perspectives for Future Applications

by Michael A. Smirnov, Vitaly K. Vorobiov, Veronika S. Fedotova, Maria P. Sokolova, Natalya V. Bobrova, Nikolay N. Smirnov and Oleg V. Borisov

Polymers 2023, 15(23), 4526; https://doi.org/10.3390/polym15234526 - 25 Nov 2023

Viewed by 1871

Abstract

This feature article is devoted to the evaluation of different techniques for producing colloidal polyelectrolyte brushes (CPEBs) based on cellulose nanofibers modified with grafted polyacrylates. The paper also reviews the potential applications of these CPEBs in designing electrode materials and as reinforcing additives. Additionally, we discuss our own perspectives on investigating composites with CPEBs. Herein, polyacrylic acid (PAA) was grafted onto the surface of cellulose nanofibers (CNFs) employing a “grafting from” approach. The effect of the PAA shell on the morphological structure of a composite with polypyrrole (PPy) was investigated. The performance of as-obtained CNF-PAA/PPy as organic electrode material for supercapacitors was examined. Furthermore, this research highlights the ability of CNF-PAA filler to act as an additional crosslinker forming a physical sub-network due to the hydrogen bond interaction inside chemically crosslinked polyacrylamide (PAAm) hydrogels. The enhancement of the mechanical properties of the material with a concomitant decrease in its swelling ratio compared to a pristine PAAm hydrogel was observed. The findings were compared with the recent theoretical foundation pertaining to other similar materials. Full article

(This article belongs to the Special Issue Polyelectrolytes and Interpolyelectrolyte Complexes)

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12 pages, 2292 KiB

Open AccessArticle

Photosensitive Spherical Polymer Brushes: Light-Triggered Process of Particle Repulsion

by Marek Bekir, Sarah Loebner, Alexej Kopyshev, Nino Lomadze and Svetlana Santer

Processes 2023, 11(3), 773; https://doi.org/10.3390/pr11030773 - 6 Mar 2023

Cited by 4 | Viewed by 2041

Abstract

We report on a light-triggered process at which repulsive interactions between microparticles with a polyelectrolyte (PE) brush coating can be remotely controlled. The spherical polyelectrolyte brushes are loaded with photosensitive azobenzene containing surfactant which can undergo reversible photo-isomerization from trans to cis state. The surfactant hydrophilicity is altered by illumination with light of an appropriate wavelength, at which a dynamic exchange of the more surface-active trans isomer in comparison to the more water soluble cis isomer with the PE brush generates a concentration gradient of the cis isomers near a solid surface where the particle is sedimented. In this way, each spherical brush produces its local lateral diffusioosmotic flow pointing outside in a radial direction resulting in mutual long-range repulsive interactions. We demonstrate that a PE layer has a higher tendency to absorb surfactant in comparison to plain silica particles, yielding a larger flow strength. This correlation holds true up to a critical intensity, where the dynamic exchange is adsorption limited with respect to trans isomers and especially pronounced for the PE-coated particles. Full article

(This article belongs to the Special Issue Photosensitive Molecular Switches: From Isolated Molecules to Processes)

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18 pages, 5197 KiB

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Application of Synchrotron Radiation X-ray Scattering and Spectroscopy to Soft Matter

by Atsushi Takahara, Yuji Higaki, Tomoyasu Hirai and Ryohei Ishige

Polymers 2020, 12(7), 1624; https://doi.org/10.3390/polym12071624 - 21 Jul 2020

Cited by 18 | Viewed by 7845

Abstract

Light produced by synchrotron radiation (SR) is much brighter than that produced by conventional laboratory X-ray sources. The photon energy of SR X-ray ranges from soft and tender X-rays to hard X-rays. Moreover, X-rays become element sensitive with decreasing photon energy. By using a wide energy range and high-quality light of SR, different scattering and spectroscopic methods were applied to various soft matters. We present five of our recent studies performed using specific light properties of a synchrotron facility, which are as follows: (1) In situ USAXS study to understand the deformation behavior of colloidal crystals during uniaxial stretching; (2) structure characterization of semiconducting polymer thin films along the film thickness direction by grazing-incidence wide-angle X-ray scattering using tender X-rays; (3) X-ray absorption fine structure (XAFS) analysis of the formation mechanism of poly(3-hexylthiophene) (P3HT); (4) soft X-ray absorption and emission spectroscopic analysis of water structure in polyelectrolyte brushes; and (5) X-ray photon correlation spectroscopic analysis of the diffusion behavior of polystyrene-grafted nanoparticles dispersed in a polystyrene matrix. Full article

(This article belongs to the Collection The Next Generation in Polymer Research)

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