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Introduction to Biopolymers, Their Blend, IPNs, Gel, Composites, and Nanocomposites

Mehvish Mumtaz1, Nazim Hussain1,*, Mubeen Ashraf2, Hafiz Muhammad Husnain Azam3, and Anwar Iftikhar1

1 Centre for Applied Molecular Biology (CAMB), University of the Punjab, Quaid-e-Azam Campus, Lahore, Pakistan
2 Department of Microbiology, University of the Central Punjab Lahore, Pakistan
3 Institute of Biotechnology, Faculty of Environment and Natural Sciences, Brandenburg University of Technology Cottbus-Senftenberg, Universitätsplatz Senftenberg, Germany
* Corresponding author

1.1 Introduction

The search to employ biomaterials in preventing the use of non-renewable commodities and to lessen the waste created by composite polymers is increasing. In the environment, a variety of bacteria and plants make biopolymers. Microbes need appropriate nutrition and a regulated microenvironment to generate biodegradable polymers. Biopolymers are categorized in a variety of ways based on their size and can be classified according to their degradation rate and the type of the subunit from which they are formed, as well as their polymeric framework [1].

Thermoplastics, thermosetting polymers, and synthetic rubber are all terms for natural polymers that become pliable at a certain elevated temperature and solidify upon cooling. Biobased thermoplastic natural polymers now outnumber thermoplastic polyamides in terms of quantity. Mixtures, hybrids, and composite materials are all classifications for natural polymers based on their content. Biobased blends are made up of polymers from several sources; for instance, the Ecovio (BASF AG), which is made up of PLA and PBAT [2]. Biocomposites are biopolymers strengthened with ordinary fibers and/or resins and preservatives, such as sisal, flax, hemp, jute, banana, wood, and other grasses [3]. A biodegradable matrix is supplemented with fibers in new composite materials. Polymeric biopolymers are polymers that have been synthesized or manipulated for a variety of uses.

Blending is a good technique for making advanced products with the right combination of qualities and may be conducted in a manufacturing environment utilizing standard machinery, thus there is no need for a large investment. Polymer mixes are being employed in a growing variety of industrial applications. The goal of blending might be to increase a material's efficiency, reduce its susceptibility to moisture, reduce costs, or strengthen the qualities for a particular function. Fragile biosurfactants have properties that are extremely similar to polystyrene (PS), a commonly used commercial thermoplastic. Inadequate mechanical properties led to the creation of several PS-based mixtures and polycaprolactone to address this issue, and PLA, as well as other natural polymers, are likely to become more common [4, 5].

Depending on the chemical ingredients, gels often comprise a material with a low molecular weight that is usually a simple solution in its perfect state (e.g., water). The existence of an additional considerably larger molecular mass constituent, which is frequently found in considerably smaller proportions than the "solvent" ingredient, is therefore attributed to the gel's flexible nature. This greater molecular weight component might be a polymeric, a colloid particle, or something else entirely; nonetheless, the gel's flexibility generally indicates that at least some of it has been formed into a full three-dimensional network across the whole hydrogel matrix. The properties are therefore substantially responsible for the processing of mechanical power throughout compression, notably the feature that when the gelatin is deformed the system filaments change in both energetic and entropic terms, contributing to a rise in the rate of energy. Loosening of this situation is generally blocked as long as the network's links stay intact, although such persistence across extended periods is far from assured. This second feature is crucial because differences in the intrinsic stability of the underlying infrastructure account for a large part of the difficulties in characterizing gels as a group of substances. In addition, when it comes to physiological gels - and those are the major topics for consideration here - great differences in cross-link durations and the ability of these connections to withstand massive deflection without collapsing are possibilities.

Nevertheless, it is widely accepted that all gels (physiological or other) have a system "component" (or "stage") and a soluble constituent, the latter of which is frequently present in significant amounts. Additional chemical constituents, such as polymers or particulates that have not yet gotten linked to the matrix, may be present in the solvent. The existence of all this low molecular weight substance, on the other hand, is one of the most (but not the most) crucial element of the gel state, because the gelatinization mechanism invariably looks to have solidified a huge volume of liquid. However, this isn't true, because the molecules are normally free to travel quickly via the channel's gaps [6].

Heterogeneous composites have already been designed to optimize the qualities of a variety of manufacturing components. Composite, blends, and IPNs all fall within the category of heterogeneous materials. Blends and IPNs are polymeric mixtures that contain two or more polymeric materials. IPNs, unlike blends, are made up of two distinct polymer systems that remain cross-linked to provide a characteristic shape. IPNs are created via interlacements among polymeric chains, while normal polymers are strengthened through inserting load bearing, strengthening fibers within their matrix.

Among the most inherent benefits of interpenetrating polymer network (IPN) composites is that they may integrate the benefits of their constituent polymerization in a single platform, resulting in improved characteristics. Because of their unique features, biopolymers have been extensively explored. IPN-based biomaterials with specialized features for a broad variety of products have been created using their chemical and structural characteristics. IPN constituents also associate the benefits of ordinary and synthetic polymers in a single organization, resulting in improved physical qualities. These types of mizes are known as blended IPNs. Hybrids IPNs have been investigated for improvement of artificial polymer characteristics. IPNs have been made from biopolymers such as polysaccharides, proteins, and polyhydroxyalkanoates (PHAs). To create hybrid IPNs or semi-IPNs, biopolymer channels have been interleaved through manufactured matrices [7].

Biobased materials are composed of compounds derived from biological material as their basic components. "Green components" are biopolymers bonded with synthetic materials and are biopolymer compounds that may be damaged by climate factors including air, light, heat, or bacteria. Natural fibers are more appealing than synthetic fibers, despite their poor ultimate tensile strength. Natural fibers provide several advantages, including simple availability, combustibility, biodegradability, and non-toxicity. Natural fibers suffer from an extensive array of reliability issues, limited computational temperatures, and excessive moisture penetration, all of which harm their use. Much research on fabricating synthetic fibers has been published showing increasing substances using organic fiber-reinforced biopolymer mixtures.

The biopolymer conditions influence the organization, conservational tolerance, and strength of a bio-based combination, whereas the reinforcing fiber affects the elasticity and properties of the composites. Biopolymer materials with commercial modern innovations have significant positive effects in global markets. The attempts to produce environmentally considerate composite materials with enhanced efficiency have yielded some significant worldwide results but are still ongoing. The aim of this analysis will be on composite materials made from polymers such as cellulose, starch, PLA, and PHA, in addition to others that are presently commercialized as well as commercially accessible, and those that are looking encouraging as mixtures for biocomposites in the coming decades [8].

Biopolymer-based nanocomposites are substances that are mostly made up of biopolymer frameworks with nanofillers scattered throughout. Natural polymers are biodegradable polymers derived from living creatures. They also feature a broad range of biological activities that enable the regulation of the boundary by nanofillers and multiresolution fabrication. They've been used in a range of ways due to their versatility in operating parameters and the low cost of their finished products. The majority of the research has concentrated on their electrical and biological applications. We will concentrate on biopolymer-based mixtures containing inert nanofillers in this study [9].

1.2 Biopolymers

Biopolymers are biomaterials that comprise monomeric components that are covalently bound and organized into custom larger compounds. The prefix "bio" indicates that the components are biodegradable and created by biological organisms. The word "biopolymer" refers to an inclusive assortment of polymers that are generally obtained from biological sources such as bacteria, plants, or forests. Biopolymers are substances created by artificial organic chemistry from biological entities like...