Special Issue on “Tailoring Polymeric Materials for Specific Applications”

Polymers are a vast class of materials that are highly tailorable to a wide variety of applications and can be modified in numerous ways. These variations include alteration of their chemistry and functional groups, varying chain length and molecular weight distributions, the addition of dopants, and copolymerizing and blending. Because of this flexibility in creating a wide range of polymeric materials, polymers can be tailored to have the specific properties required for a given application. For this reason, polymeric materials are widely used and ubiquitous in our everyday lives.

This Special Issue on “Tailoring Polymeric Materials for Specific Applications” gathers recent work on the design and modification of polymeric materials for a variety of applications. These applications include packaging and biodegradable films [1,2], capacitors [3], and water treatment [4,5,6]. In addition, papers which provide a better understanding of specific processes, including chain-end coupling [7], additive manufacturing [8], and surface characterization [9], also lie within this Special Issue.

The modification of polymeric materials can be performed in a variety of ways to achieve a desired result, including blending [1] and doping [2,3]. When blending polymers, it is important that the polymers are compatible. In the case of noncompatible polymers, such as in hydrophobic–hydrophilic systems, compatibilizers may be added during the mixing process to increase favourable interactions and compatibility. For example, thermoplastic starch (TPS) and poly lactic acid (PLA) can be effectively blended using organic acids [1]. Doping a polymeric material with a small amount of additive is carried out to improve specific properties. Often, plasticizers are added to polymers to improve their processability; however, polymers may be doped with other compounds to improve many different properties. For example, chitosan can be doped with glycerol to increase the flexibility of films [2]. In addition, imidazolium-based ionic liquids can be used to dope poly (vinylidene fluoride) (PVDF) and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to modify their electric properties [3].

Tailoring polymeric materials for a specific application can also begin with selecting polymeric materials with appropriate functional groups and/or properties. For absorbent materials used in removal of heavy metals in wastewater applications, the functional groups on the polymer are what attract and bind the analytes [10]. Nitrogen and oxygen containing groups (such as amine, carboxyl, hydroxyl, and cyano groups) are often used in sorption and removal of metal ions in aqueous environments. For example, samarium (III) may be removed using polyacrylonitrile—partially reduced graphene oxide (PAN-PRGO) [4] and chromium (VI) may be removed using polypyrrole doped with magnetic hematite (Fe₃O₄)—chitosan nanoparticles (Ppy@magnetic chitosan nanocomposite) [5]. Similarly, removal of organic compounds, such as dyes, from wastewater is also dependent on the attraction between the analyte and absorbent. For example, methyl orange may be removed using either Ppy@magnetic chitosan nanocomposite [5] or aloe vera [6].

Polymer modification may also be achieved through novel synthesis techniques. For example, molecular weights can be increased through chain-end coupling. Therefore, a synthetic method that promotes chain-end coupling through atom transfer radical coupling (ATRC) can be used to tailor the molecular weights and related properties of polymeric materials [7]. In addition, modifications may also be made during the extrusion process where temperature and shear forces may degrade the polymeric material. Modelling the extrusion process can improve understanding of the melt efficiency and aid in determining the optimal operating and material parameters for a particular system [8].

To improve understanding of how materials perform and, thus, for which applications they may be used, it is important to evaluate various properties of new materials. The effect of these modifications on the material properties is often performed relative to the unmodified polymeric material. For example, TPS–PLA blends were evaluated for thermal properties, mechanical properties, and hydrophobicity relative to both TPS and PLA [1] and acrylonitrile butadiene styrene (ABS)-polycarbonate (PC) blends were evaluated relative to both ABS and PC for surface mechanical properties using nano-indentation [9]. In addition, it is valuable to compile the properties of various novel materials as a comprehensive reference, as is often done in review papers on specific types of materials. For example, the physiochemical properties of PVDF and PVDF–HFP blends are included in a review of PVDF/imidazolium-based ionic liquid blends and composites [3].

Polymeric materials can be modified in a variety of ways, which influences their properties and, thus, their suitability for an application. A better understanding of the polymeric materials, their properties, and their preparation processes leads to more efficient material design and selection for target applications. This Special Issue on “Tailoring Polymeric Materials for Specific Applications” focuses on recent work carried out in the field of the design and modification of polymeric materials for various specific applications.