Chapter 2 Smart Hydrogels

  • Published 2017

Abstract

This chapter focuses on the synthesis, characterization, and applications of stimuli-responsive hydrogel-based materials. Hydrogels are three-dimensional (3D) materials with the ability to absorb large amounts of water while maintaining their dimensional stability. The 3D integrity of hydrogels in their swollen state is maintained by either physical or chemical crosslinking [1–3]. Chemically crosslinked networks have permanent junctions, while physical networks have transient junctions that arise from either polymer chain entanglements or physical interactions such as ionic interactions, hydrogen bonds, or hydrophobic interactions [4]. Indeed, there are many different macromolecular structures that are possible for physical and chemical hydrogels. They include the following: crosslinked or entangled networks of linear homopolymers, linear copolymers, and block or graft copolymers; polyion-multivalent ion, polyion–polyion or H-bonded complexes; hydrophilic networks stabilized by hydrophobic domains; and interpenetrating polymer networks (IPNs) or physical blends. Hydrogels may also have many different physical forms, including (a) solid molded forms (e.g., soft contact lenses), (b) pressed powder matrices (e.g., pills or capsules for oral ingestion), (c) microparticles (e.g., as bioadhesive carriers or wound treatments), (d) coatings (e.g., on implants or catheters; on pills or capsules, or coatings on the inside capillary wall in capillary electrophoresis), (e) membranes or sheets (e.g., as a reservoir in a transdermal drug delivery patch; or for 2D electrophoresis gels), (f) encapsulated solids (e.g., in osmotic pumps), and (g) liquids (e.g., that form gels upon heating or cooling) [5]. Hydrogels can also be separated into two groups on the basis of their natural or synthetic origins [6, 7]. Hydrogel-forming natural polymers include proteins such as collagen and gelatin, and polysaccharides such as alginate and agarose. These hydrogels have many advantageous features, including low toxicity and good biocompatibility, because their chemical structures are similar to those of the bioactive glycosaminoglycan (GAG) molecules (e.g., heparin sulfate, chondroitin sulfate, and hyaluronan) present in the native extracellular Chapter 2 Smart Hydrogels

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Cite this paper

@inproceedings{2017Chapter2S, title={Chapter 2 Smart Hydrogels}, author={}, year={2017} }