Hydrogels SAPs

Hydrogels, 13 729-759. See also Microgels Superabsorbent polymers (SAPs) AMPS polymer, 23 721 applications for, 13 747-753 biodegradable, 13 739-742 bioerodible, 9 63 conducting, 7 524 cross-linked poly (ethylene oxide),... 

Water absorbing polymers, sometimes referred to as hydrogels, absorb aqueous solutions through hydrogen bonding with the water. An SAP s ability to absorb water is a factor of the ionic concentration of an aqueous solution. In deionized and distilled water, SAP may absorb 500 times its weight (from 30 to 60 times its own volume), but when put into a 0.9% saline solution, the absorbency drops to maybe 50 times its weight. The presence of valent cations in the solution will impede the polymer s ability to bond with the water molecule. 

The addition of hydrogel in the soil resulted in a favorable alteration in the soil physical characteristics, such as porosity and bulk density (Table 4.1). The increased dimension in the swollen form of the hydrogel resulted in an increased porosity of the soil and increased availability of oxygen to the roots (Fannery and Busscher, 1982). The expansion and contraction of SAP in the soil during water absorption and evaporation helps to improve the air content in the soil (Buchholz and Graham, 1997). The study showed that the use of the starch-based SAP hydrogel amendment is useful for increased plant establishment, especially, in drought-prone areas. 

Peptide-based nanoflbrous hydrogels, such as the previously described SAPs, have great potential for the controlled release of these exogenous growth factors. There are several techniques currently available to achieve protein delivery via biomaterials (i) modification of the biomaterial so that it may be tether the protein to it (ii) incorporation or encapsulation of the growth factor by the material to allow controlled release (iii) proteolytic release in which the growth factor is tethered by an enzyme degradable... 

SAPs known as hydrogels are hydrophilic cross-linked polymers that swell in water. These products utilize SAP (normally in powder form) to create the absorbent core, which acts as the storage stmcture in the product. Sometimes they are called intelhgent gels because 1 g of hydrogel can absorb even up to 1000 g of water. The SAP particles usually have a sand-like feature, which is not comfortable when it mbs against skin. Also, its gel-like behaviour when wet does not produce a desirable feeling if it comes into contact with the skin. 

The mole ratios of chitosan and PEG 1450 were varied from 1 0.1 to 1 0.3 to observe the effect of crosslinking density on the stress at maximum load of the SAP. The SAPs with the mole ratios of 1 0.1, 1 0.2, 1 0.3 gave the stress at the maximum load for 4, 5 and 6 kPa, respectively. This implies that PEG is a practical crosslinker to control the hydrogels with different properties resulting in SAP chitosan. 

Fluid seeding is a method in which seeds are mixed with hydrogel and after they germinate, they are planted in a field [7]. As the fluid, a SAP is used. The requirements for the fluid are ... 

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