Which polymer shows pH dependent swelling?
The chemical structure of xanthan is shown in Figure 8. Figure 8. Chemical structure of Xanthan. Xanthan, being an ionic polymer, containing a carboxylic group on one of the side chain of glucuronic acid is pH sensitive and shows much swelling in basic environment due to complete ionization of the carboxylic group.
What polymers are commonly used in hydrogels?
Hydrogel-forming natural polymers include proteins such as collagen and gelatine and polysaccharides such as starch, alginate, and agarose. Synthetic polymers that form hydrogels are traditionally prepared using chemical polymerization methods.
How do you increase hydrogels?
Thus, hydrogels can be reinforced through many established kinds of methods and techniques: block copolymers, in which hydrophobic and hydrophilic domains alternate [7], increasing crosslinking density [8], by means of binary systems composed of two or more mixed polymers as interpenetrating polymer networks [9], by …
How does pH affect the swelling of hydrogels?
Effect of pH on swelling Slight change in swelling ratio of the biomineralized hydrogels has been noticed when placed in various pH of the aqueous solution. It can also be noticed that irrespective of sample thickness at neutral pH = 7, all samples show a higher value of swelling ratio.
What is the difference between Aerogel and hydrogel?
Hydrogel and alcogel terms are used when the liquid (solvent) in the gel network is water and alcohol, respectively. Whereas when the liquid from the gel is extracted at supercritical state of liquid, these materials are called aerogels. Aerogels are generally monolithic and have low density than xerogels.
What is polymer hydrogel?
A hydrogel is a three-dimensional (3D) network of hydrophilic polymers that can swell in water and hold a large amount of water while maintaining the structure due to chemical or physical cross-linking of individual polymer chains. Hydrogels were first reported by Wichterle and Lím (1960) [1].
How hydrogels are formed?
Hydrogels are degradable polymeric networks, in which cross-links play a vital role in structure formation and degradation. By crosslinking, hydrogels are formed into stable structures that differ from their raw materials. Generally, hydrogels can be prepared from either synthetic or natural polymers.