kDa Definition of Dalton

500 kDa is a unit of molecular weight, representing 500,000 Daltons. Dalton (Da) is a common unit of molecular weight used to describe the mass of a molecule or polymer chain. Here is a detailed explanation:

Definition of Dalton

- 1 Dalton (Da) is equal to the mass of 1 hydrogen atom (H), which is about \(1.66 \times 10^{-24}\) grams.

- Molecular Weight (MW) refers to the sum of the masses of all atoms in a molecule. For example, the molecular weight of water is about 18 Da (2 hydrogen atoms + 1 oxygen atom).

The meaning of 500 kDa

- 500 kDa means that the mass of the polymer chain is 500,000 Daltons, which is the mass of 500,000 hydrogen atoms.

- For polymer materials such as sodium polyacrylate, 500kDa belongs to the medium-high molecular weight range.

- Low molecular weight: < 100 kDa

- Medium molecular weight: 100 kDa ~ 500 kDa

- High molecular weight: 500 kDa ~ 2 MDa

- Ultra-high molecular weight: > 2 MDa

Effect of molecular weight on polymer properties

- 500 kDa sodium polyacrylate has the following characteristics:

- Physical entanglement: The chain segments are relatively long, and a secondary network can be formed through physical entanglement to enhance the cohesion of the gel.

- Swelling properties: It swells evenly after absorbing water, and is suitable for use in cooling patches and other scenes that require a stable gel structure.

- Processability: The dissolution rate is moderate and it is easy to process into gel or film.

The significance of molecular weight distribution

- Molecular weight distribution (PDI) refers to the degree of dispersion of different molecular weight segments in a polymer.

- Narrow distribution (PDI < 1.5): uniform molecular weight, stable performance, but may have poor toughness.

- Broad distribution (PDI > 2.0): contains long and short segments, short chains fill the network gaps, and long chains provide strength, suitable for applications requiring high toughness.

500 kDa in practical applications

- Cooling patch: 500 kDa sodium polyacrylate forms a stable gel through physical entanglement and chemical cross-linking, providing good adhesion and water absorption.

- Hydrogel: 500 kDa segment length is moderate, suitable for the preparation of highly absorbent and high-strength hydrogels.

Summary

500 kDa means the mass of the polymer chain is 500,000 Daltons, which belongs to the medium-high molecular weight range. This molecular weight of sodium polyacrylate shows excellent mechanical properties and processability in applications such as cooling patches and hydrogels.