lowgelling

Lowgelling refers to the property of certain sols or polymers to form a gel at relatively low temperatures, with the gel point occurring near ambient or refrigeration temperatures rather than at higher heat. This term is used to distinguish gels that set easily in cool or room conditions from those that require substantial heating to initiate or sustain gelation.

The gelation mechanism in lowgelling systems typically involves physical or chemical cross-linking that can proceed at lower thermal energy. Factors that promote low-temperature gelation include polymer concentration, molecular weight, and architecture, as well as environmental conditions such as pH, ionic strength, and the presence of multivalent ions or plasticizers. Some polysaccharide networks form through ionic cross-links or hydrogen bonding that stabilize the gel at lower temperatures, while others rely on thermally induced rearrangements that occur near ambient ranges.

Determinants and measurement: The ease of low-temperature gelation depends on polymer type, additives, and processing history. Rheological measurements are commonly used to identify the gel point, often marked by the crossover of storage and loss moduli (G' and G''). Differential scanning calorimetry can detect associated thermal transitions. Practical assessments may note the temperature at which the material loses flow or gains noticeable rigidity.

Applications and limitations: Lowgelling gels are advantageous in food, pharmaceutical, and biomedical formulations where setting at or below room temperature is desirable.Limitations can include reduced mechanical strength, stability under storage, and potential syneresis or phase separation if the network is not sufficiently robust.

See also: gel point, thermo-reversible gels, cross-linking.