molecules
Review Spherical Polyelectrolyte Brushes as Flocculants and Retention Aids in Wet-End Papermaking NaSu
Department of Printing and Packaging Engineering, Shanghai Publishing and Printing College, Shanghai 200093, China; suna@whu.edu.cn
Abstract: As the criteria of energy conservation, emission reduction, and environmental protection become more important, and with the development of wet-end papermaking, developing excellent retention aids is of great significance. Spherical polyelectrolyte brushes (SPBs) bearing polyelectrolyte chains grafted densely to the surface of core particle have the potential to be novel retention aids in wet-end papermaking not only because of their spherical structure, but also due to controllable graft- ing density and molecular weight. Such characteristics are crucial in order to design multi-functional retention aids in sophisticated papermaking systems. This review presents some important recent advances with respect to retention aids, including single-component system and dual-component systems. Then, basic theory in papermaking is also briefly reviewed. Based on these advances, it emphatically describes spherical polyelectrolyte brushes, focused on their preparation methods, characterization, conformation, and applications in papermaking. This work is expected to contribute to improve a comprehensive understanding on the composition, properties, and function mechanisms of retention aids, which helps in the further investigation on the design of novel retention aids with excellent performance.
Keywords: spherical polyelectrolyte brushes; flocculation; retention aids; wet-end papermaking
1. Introduction The wet-end of papermaking is a very complex system, where paper stock is a sus- pension based on fibers with water as the medium. The components of paper stock are relatively complex [1], mainly including the following components: (a) Fibers. Based on the source of raw materials, these can be divided into wood pulp, reed pulp, straw pulp, etc. The chemical components mainly include cellulose, hemicellulose, and lignin. (b) Granular fillers. These consist of inorganic fillers such as ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), kaolinite, talc powder, titanium dioxide, etc., and organic polymer fillers such as polyethylene fillers, fiber fillers, etc. The filler particle size is generally less than 10 μ m [2]. (c) Various additives. These can be divided into two categories [3]: process additives and functional additives. The former includes retention aids, filter aids, defoamers, fungicides, etc., with a focus on improving economic benefits [4,5]. The latter is mainly designed to improve the end-use properties of papers, involving sizing agents [6], dry strength agents [7], wet strength agents, whitening agents, etc. (d) Soluble inorganic salts and other impurities. The development of the papermaking industry has put forward higher requirements for the application of wet-end chemicals in papermaking. Two application purposes of wet-end chemicals are mainly involved. One is to gain access to various properties of paper. The other is to increase production efficiency and improve the operation of the paper machine. Accordingly, wet-end additives are mainly divided into two categories: functional additives and process additives. The classification of wet-end chemicals in papermaking is shown in Figure 1.
Citation: Su, N. Spherical Polyelectrolyte Brushes as
Flocculants and Retention Aids in Wet-End Papermaking. Molecules 2023 , 28 , 7984. https://doi.org/ 10.3390/molecules28247984
Academic Editor: Ecaterina Stela Dragan
Received: 6 November 2023 Revised: 2 December 2023 Accepted: 5 December 2023 Published: 7 December 2023
Copyright: © 2023 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
Molecules 2023 , 28 , 7984. https://doi.org/10.3390/molecules28247984
https://www.mdpi.com/journal/molecules
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