gelforming

Gelforming, or gel formation, refers to the transition of a sol into a gel, resulting in a semi-solid material in which a three-dimensional polymer network immobilizes a substantial amount of water. The gel behaves as a solid-like substance while retaining liquid-like mobility of its fluid component.

In physical gels, crosslinks arise from non-covalent interactions such as hydrogen bonds, ionic associations, or hydrophobic effects, and many gels are reversible with changes in temperature, pH, or salinity. In chemical gels, covalent crosslinks form through reactions such as polymerization, condensation, or enzymatic linking, yielding more permanent networks.

Common gelforming systems include natural polysaccharides such as gelatin, agar, alginate, carrageenan, and pectin, as well as proteins and synthetic polymers like polyvinyl alcohol or polyacrylamide. Gel strength and texture depend on the polymer type, concentration, molecular weight, crosslink density, and environmental conditions including temperature, pH, and ionic strength.

Gel formation is widely used in food technology to set jams and yogurts, in biomedical fields for drug delivery and tissue engineering, in cosmetics, and in materials science for hydrogels and soft robotics. The process can be thermo-reversible or permanently crosslinked, and the term gelation is used to describe the onset or progression of gel formation.