Natural Polymers

Polymers can be classified based on their origin as natural or synthesis. Other texts have classified polymers according to functions, source, polymerization mechanism, polymer structure, preparation techniques, and thermal behavior. This chapter provides information on a system of classifying natural polymers with respect to their sources. It also discusses some of the most widely used natural polymers in industries. Proteins, polysaccharides, polynucleotides, polyisoprenes, and polyesters are discussed.

This chapter covers recent techniques applied in processing and characterization of natural polymers. This includes techniques in processing natural polymers from their natural forms into modified forms for more varied application and functionality. It also looks at techniques for processing modified and unmodified natural polymers for various purposes such as film formation for transdermal patches, composite and blends production to form films with improved mechanical properties, magnetic decoration for production of tough membranes with magnetic properties. The characterization methods covered in this chapter include X-ray diffraction, microscopy, and Fourier transform infrared spectrometry. We look at recent reported processing and characterization techniques which are applicable to the major industries today for natural polymer-based materials.

Natural polymers gelatine, chitin, chitosan, cellulose, starch, and pectin are reviewed here with focus on their extraction methods, looking at how they are purified and the extent of modifications in their extraction and utilization. Various techniques exist for the extraction of these polymers from their natural sources which are mainly plants, insects, or fish. Within the chapter the acid and the alkaline processes usually used to extract gelatine are discussed. The gelatin prepared by the acid process is called type A gelatin, whereas that prepared by the alkaline process is called type B gelatine. Sorghum and melon bugs provide an alternative source acceptable for Halal products and serve as an alternative for markets concerned about bovine spongiform encephalopathy (BSE). Chitin extraction involves demineralization and deproteinization steps, which can be conducted by chemical or biological method. The chemical extraction requires the use of acids and bases, while the biological method involves microorganisms. Chitosan is synthesized by deacetylation of chitin using sodium hydroxide to remove the proteins in the source followed by demineralization to remove the carbon and other salts present in crude form. These and others are discussed within the chapter.

The main areas of biomedicine where biopolymers find applicability include tissue engineering, bone repair/replacement, dental repair/replacement, controlled drug delivery and skin repair.

In food, natural polymers encompass a range of proteins and polysaccharides that are widely used in a variety of industrial applications to perform a number of functions including gelling and thickening aqueous solutions, as well as stabilizing foams, emulsions and dispersions, inhibiting ice and sugar crystal formation, and control the release of flavors. In the food technology field, proteins, and polysaccharides when used as additives and ingredients in food formulations, are often referred to as “hydrocolloids.” Hydrocolloids are a heterogeneous group of long chain natural polymers characterized by their ability to form viscous dispersions and/or gels when dispersed in water (Saha and Bhattacharya in J Food Sci Technol 47:587–597, 2010). These polymers are generally hydrophilic due to the large number of hydroxyl (−OH) groups imparting a high affinity for binding water molecules, allowing them to be dispersed in water in the colloidal state. Thus, the origin of their name—hydrophilic colloids or hydrocolloids, which in the context of this chapter can be considered interchangeable with “natural polymers.” This chapter reviews the main applications of natural polymers in food, specifically, the stabilization of emulsions, modification of texture by the action of thickening and gelling, as well as some additional functions polymers can provide with respect to preservation, health, and nutrition. It also provides some market figures on the volumes, prices, and key drivers for the development of natural polymers as food additives and ingredients.

Currently, the packaging sector is a major consumer in the most industries. Plastic packaging is being increasingly used in medical products and healthcare as well as in the beverages and packaged foods.

This chapter is divided into three parts. The first part describes the role of natural polymers in the nonrenewable energy industry (drilling fluids) and this includes the definition, function, properties, additives, and types of drilling muds. In this part the problems of drilling fluid loss during its circulation at the oil field well and its solution using the natural polymers are also discussed. The second part deals with the role of natural polymers in the renewable energy industry (biomass), this part reviews the types of renewable energy produced from biomass. Finally, the third part focuses on the role of natural polymers in the wastewater treatment technology.

Cosmetic and personal care products are complex mixtures intended to be applied to the external parts of the human body. In the long list of ingredients are included polymers which are either natural or synthetic. This chapter presents the main natural polymers used in cosmetics which are mainly polysaccharides and proteins obtained from vegetable, animal and biotechnology origins. The use of artificial polymers is discussed through the example of cellulose derivatives which are widely used for their physicochemical properties and cosmetic benefits. Natural polymers in cosmetics play many distinct roles; they can be chosen either to improve the stability of colloidal systems, to control the rheological properties from manufacturing to end-user or to achieve the sensory expectation and efficiency of the product during application. Natural polymers are thus multifunctional ingredients used in many different commodities sometimes alone, but more often in combination with synthetic polymers as illustrated through different examples including hair care, skin care or toothpaste products. Natural polymers own a growing place in the cosmetic field and this can be attributed to the ever increasing desire for “naturality”. Their applicability in this field is further enhanced by their processibility and the multiple options possible to control properties through their chemical modifications.

This chapter covers the pharmaceutical application of natural polymers derived from carbohydrate and protein sources in modified and unmodified forms for pharmaceutical applications such as production of transdermal, percutaneous, oral and topical drug delivery systems. Hydrogel-and microgel-based drug delivery systems are also included due to their increasing importance and potential in the pharmaceutical industry. A detailed overview of the distinctive properties of natural polymers suitable for pharmaceutical applications is provided from the most recent applications reported in the literature.

In 1920, the Nobel laureate Hermann Staudinger recognized that natural and man-made polymers are produced according to the same blueprint: a very large number of small monomer molecules are linked together to produce high-molecular-weight macromolecules (Staudinger, Ber. Deutschen Chem. Ges. 53:1073–1085, 1920).

The importance of natural polymers in providing quality and sustainable condition of living for people, globally, cannot be overemphasized. The economic impacts of natural polymers are enormous and inexhaustible to the extent that they are universal, indispensable, life support materials whose occurrence may not be quantified absolutely. Natural polymers are abundant, renewable, diverse, versatile, biodegradable, biocompatible, safe, non-toxic and inexpensive sources of biomaterials. Biomaterials have been used for more than 2000 years and natural polymers, through research and development employing scientific and industrial processes; are being innovated into several materials with applications in medical, pharmaceutical, agricultural, food and beverages, toiletries, cosmetics, textiles and other industrial, domestic and personal care products. The usefulness of natural polymers to man and its applications in the modern world has resulted in various capacities of scientific, engineering and technological manpower and industrial development. There is remarkable investment in studies and manufacture of different products from rubber, cotton, paper and other traditional commodities; to films, plastics, the novel tissue engineering and nanodrug delivery systems. The global biomaterials market was estimated in a market research report to reach US $88.4 billion by 2017. However, the imbalance in capital and technology stock between developed and less developed countries may have limited the benefits of natural polymers to North America and a few other countries in the West, Asia and Latin America. Market imperfections, such as protectionism, stringent regulatory systems, patent, tariff barrier and potential economic dependency may be some of the greatest challenges in globalizing the desired economic impact of natural polymers.

In this chapter, we look at the current trends and challenges in natural polymers in industry and give some perspectives for the future. We look at the technologies in development with regards to natural polymers’ applications in industry today, identify some limitations in applications and processing, and propose some approaches to address such. The sections are divided according to the selected applications from those discussed in the previous chapters in the respective industry. The areas covered include cosmetics, food, engineering, and general applications.