Sodium polyaspartate

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Sodium polyaspartate
Sodium polyaspartate.png
Identifiers
CAS number 94525-01-6 (for (α,β)-DL-polysodiumaspartate)
Properties
Molecular formula (C4H4NNaO3)n
Molar mass variable
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Sodium polyaspartate is a sodium salt of polyaspartic acid. It is biodegradable condensation polymer based on the amino acid aspartic acid.

Polymerization[edit]

The polymerization reaction is an example of a step-growth polymerization to a polyamide and in one practical procedure[1] aspartic acid is simply heated to 180 °C resulting in water release and the formation of a poly(succinimide). In the subsequent step, this polymer is reacted with sodium hydroxide in water, which hydrolyzes one of the two amide bonds of the succinimide ring to form a sodium carboxylate. The remaining amide bond is thus the linkage between successive aspartate units. Each aspartate unit is identified as α or β according to which carbonyl of it is part of the polymer chain. The α form has one carbon in the backbone in addition to the carbonyl itself (and a two-carbon sidechain) whereas the β form has two carbons in the backbone in addition to the carbonyl itself (and a one-carbon sidechain). This reaction gives a sodium poly(aspartate) copolymer composed of approximately 30% α-linkages and 70% β-linkages.

Synthesis of sodium poly(aspartate)

Uses[edit]

This material can be synthesized in an environmentally friendly way and is biodegradeable, thus it is a green alternative to several materials such as sodium polyacrylate used in disposable diapers and agriculture.[2][3]

In addition and due to its water-solubility and ability to chelate metal ions, polyaspartate is used as a biodegradeable anti-scaling agent and a corrosion inhibitor.[4][5]

See also[edit]

Polyaspartic acid


References[edit]

  1. ^ Bennett GD (2005). "A Green Polymerization of Aspartic Acid for the Undergraduate Organic Laboratory" (Abstract). J. Chem. Educ. 82 (9): 1380–1381. Bibcode:2005JChEd..82.1380B. doi:10.1021/ed082p1380. 
  2. ^ Gross, R. A.; Kalra, B. (2002). "Biodegradable Polymers for the Environment". Science 297 (5582): 803–807. Bibcode:2002Sci...297..803G. doi:10.1126/science.297.5582.803. PMID 12161646. 
  3. ^ "Presidential Green Chemistry Challenge Awards: 1996 Small Business Award: Donlar Corporation (now NanoChem Solutions, Inc.): Production and Use of Thermal Polyaspartic Acid". US Environmental Protection Agency. 
  4. ^ Low, K. C.; Wheeler, A. P.; Koskan, L. P. (1996). Commercial poly(aspartic acid) and Its Uses. Advances in Chemistry Series 248. Washington, D.C.: American Chemical Society. 
  5. ^ Thombre, S.M.; Sarwade, B.D. (2005). "Synthesis and Biodegradability of Polyaspartic Acid: A Critical Review". Journal of Macromolecular Science, Part A 42 (9): 1299–1315. doi:10.1080/10601320500189604.