Hydrogel- and aerogel-based composites

Polymer blends of natural and biodegradable synthetic materials have superior properties; however, compatibility between them must, however, be addressed first. A polymer with a superior property either enhances or disrupts the inferior polymer property, in which the primary aim of blending two or more polymers is to produce a new, enhanced material. Natural polymers such as lignocellulosic-based material are inexhaustible natural polymers. They are the most favorable for blending due to their flexibility and biocompatibility which can meet the needs of advanced technology. The use of natural polymer technologies facilitates the use of environmentally friendly materials. Nonetheless, it is not appropriate to disregard the capacity of synthetic polymers to emulate natural polymers. Polymer blending frequently involves a melting or dissolving process, in which the polymers are homogeneously or heterogeneously mixed before the regeneration process. Many regenerated products, including hydrogel, aerogel, cryogel, xerogel, etc., are produced from natural and inorganic blends. The notion of regeneration is generally extended to the hydrogel but not always to the aerogel. Even so, for hydrogels and aerogels, their applications are vast but predominantly they are used in medical and agricultural products. They are considered propitious alternatives with properties equal to or greater than nonbiodegradable synthetic products that are currently available due to their moldability and biocompatibility. They are also regarded as smart materials based on their capability to respond to environmental stimuli. The importance of blending natural and biodegradable synthetic polymers is authenticated as a more durable alternative and it becomes more pronounced, considering the various products produced from them. Due to the coherence of blended polymers, composite products developed on polymer blends have immense potential, stretching to more complex applications. Therefore, this chapter highlights the polymer blending of lignocellulose-based (e.g., cellulose, hemicellulose, and lignin) and synthetic-based (e.g., polyurethane, polylactic acid, polyvinyl alcohol, and polyethylene glycol) biodegradable hydrogels and aerogels with various other polymer materials explicitly used for medicine and agriculture applications.