Polyaspartic acid

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Polyaspartic acid
Polyaspartic acid.png
Other names
  • none
Molar mass variable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Polyaspartic acid (PASA) is a biodegradable, water-soluble polymerized amino acid.[1] It is a biodegradable replacement for water softeners and related applications.

In nature, PASA has been found in as fragments of larger proteins with length up to 50 amino acids,[2] but as of 2004 had not been isolated as a pure homo polymeric material from any natural source.[3] The first isolation of synthetic oligomeric sodium polyaspartate, obtained by thermal polycondensation of aspartic acid, was reported by Hugo Schiff in late 19th century.[4] Later it was proposed that thermal polymerization process leads through polysuccinimide intermediate.[5][6] Polyaspartic acid is produced industrially in both the acid form and as the sodium polyaspartate salt.

Properties and structure[edit]

Due to presence of carboxylic groups it is polyelectrolyte with anionic character. Naturally occurring PASA fragments consists of α,-linked L-aspartatic acid.[2] In contrast, the repeating unit of synthetic polyaspartic acid may exist in four isomeric forms, depending on the stereochemistry of starting material (D- and L-aspartic acid) and synthetic procedure leading to α and β links.


Some synthetic strategies leading to polyaspartic acid
Isomers of PASA repeating unit

Many different routes lead to PASA. In the simplest[7] and the oldest approach[3] aspartic acid is heated to induce dehydration. In a subsequent step the resulting polysuccinimide is treated with aqueous sodium hydroxide, which yields partial opening of the succinimide rings. In this process sodium-DL-(α,β)-poly(aspartate) with 30% α-linkages and 70% β-linkages[8] randomly distributed along the polymer chain,[9] and racemized chiral center of aspartic acid is produced.[10] There were many catalysts reported for improving thermal polymerization method. Main benefits from their application is increasing of the conversion rate and higher molecular weight of the product.[11][12] Polyaspartic acid can also be synthesized by polymerization of maleic anhydride in presence of ammonium hydroxide.[1][13] High control over repeating unit isomers can be achieved by polymerization of N-carboxyanhydride (NCA) derivatives,[14] by polymerization of aspartic acid esters[15] or by application of enzyme catalyzed reaction.[16] Pure homopolymers, D- or L-PASA with α- or β-links only, can be synthesized using those methods.


Polyaspartic acid and its derivatives are biodegradable alternatives to traditional polyanionic materials, in particular polyacrylic acid.[17] PASA has ability to inhibit deposition of calcium carbonate, calcium sulfate, barium sulfate, and calcium phosphate and can be used as an antiscalining agent in cooling water systems, water desalination processes, and waste water treatment operations.[18] In addition and due to its ability to chelate metal ions, it provides corrosion inhibition.[8] It can act as a super-swelling material in diapers, feminine hygiene products, and food packaging.[19] It can also be used as biodegradable detergent and dispersant for various applications.[20]


  1. ^ a b Thomas Klein, Ralf-Johann Moritz and René Graupner (2008). "Polyaspartates and Polysuccinimide". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.l21_l01. 
  2. ^ a b Rusenko, Kirt W.; Donachy, Julie E.; Wheeler, A. P. (1991). "Purification And Characterization Of A Shell Matrix Phosphoprotein From The American Oyster". In Sikes, C. Steven; Wheeler, A. P. Surface Reactive Peptides and Polymers. ACS Symposium Series. 444. ACS. pp. 107–124. doi:10.1021/bk-1991-0444.ch008. ISBN 9780841218864. 
  3. ^ a b Joentgen, Winfried; Müller, Nikolaus; Mitschker, Alfred; Schmidt, Holger (2004). "Polyaspartic acids". In Fahnestock, Stephen; Steinbüchel, Alexander. Polyamides and Complex Proteinaceous Materials I. Biopolymers. 7. Wiley-VCH. pp. 175–179. ISBN 9783527302222. 
  4. ^ Schiff, Hugo (1897). "Ueber Polyaspartsäuren". Ber. Dtsch. Chem. Ges. (in German). 30 (3): 2449–2459. doi:10.1002/cber.18970300316. 
  5. ^ Kovács, J.; Könyves, I.; Pusztai, Á. (1953). "Darstellung von Polyasparaginsäuren (Polyaspartsäuren) aus dem thermischen Autokondensationsprodukt der Asparaginsäure". Experientia (in German). 9 (12): 459–460. doi:10.1007/BF02165821. 
  6. ^ Kovács, J.; Könyves, I. (1954). "Uber DL-α,β-Polyasparaginsaure". Naturwissenschaften (in German). 41 (14): 333. Bibcode:1954NW.....41..333K. doi:10.1007/BF00644501. 
  7. ^ Bennett, G. D. (2005). "A Green Polymerization of Aspartic Acid for the Undergraduate Organic Laboratory". Journal of Chemical Education. 82 (9): 1380–1381. Bibcode:2005JChEd..82.1380B. doi:10.1021/ed082p1380. 
  8. ^ a b Low, Kim C.; Wheeler, A. P.; Koskan, Larry P. (1996). "6: Commercial Poly(aspartic acid) and Its Uses". In Glass, J. Edward. Hydrophilic Polymers. Advances in Chemistry. 248. ACS. pp. 99 –111. doi:10.1021/ba-1996-0248.ch006. ISBN 9780841231337. 
  9. ^ Pivcova, H.; Saudek, V.; Drobnik, J.; Vlasak, J. (1981). "NMR Study of Poly(aspartic acid). I. α-and β-Peptide Bonds in Poly(aspartic acid) Prepared by Thermal Polycondensation". Biopolymers. 20 (8): 1605–1614. doi:10.1002/bip.1981.360200804. 
  10. ^ Kokufuta, Etso; Suzuki, Shinnichiro; Harad, Kaoru (1978). "Temperature Effect on the Molecular Weight and the Optical Purity of Anhydropolyaspartic Acid Prepared by Thermal Polycondensation". Bulletin of the Chemical Society of Japan. 51 (5): 1555–1556. doi:10.1246/bcsj.51.1555. 
  11. ^ Nakato, Takeshi; Kusuno, Atsushi; Kakuchi, Toyoji (2000). "Synthesis of poly(succinimide) by bulk polycondensation of L-aspartic acid with an acid catalyst". Journal of Polymer Science Part A: Polymer Chemistry. 38 (1): 117–122. doi:10.1002/(SICI)1099-0518(20000101)38:1<117::AID-POLA15>3.0.CO;2-F. 
  12. ^ Wang, Yaquan; Hou, Yongjiang; Ruan, Gang; Pan, Ming; Liu, Tengfei (2003). "Study on the polymerization of aspartic acid catalyzed by phosphoric acid". Journal of Macromolecular Science-Pure and Applied Chemistry. A40 (3): 293–307. doi:10.1081/MA-120018116. 
  13. ^ US patent 5468838, Boehmke, Gunter & Schmitz, Gerd, "Polysuccinimide, polyaspartic acid and their salts are prepared by reaction of maleic anhydride and ammonia, polycondensation of the resulting product in the presence of a solubilizing agent and, if appropriate, hydrolysis.", published 1995-11-21, assigned to Bayer AG 
  14. ^ Rao, Vanga S.; Lapointe, Philippe; McGregor, Donald N. (1993). "Temperature Effect on the Molecular Weight and the Optical Purity of Anhydropolyaspartic Acid Prepared by Thermal Polycondensation". Makromolekulare Chemie-Macromolecular Chemistry and Physics. 194 (4): 1095–1104. doi:10.1002/macp.1993.021940405. 
  15. ^ Saudek,, V.; Pivcova, H.; Drobnik, J. (1981). "NMR Study of Poly(aspartic acid). II. α-and β-Peptide Bonds in Poly(aspartic acid) Prepared by Common Methods". Biopolymers. 20 (8): 1615–1623. doi:10.1002/bip.1981.360200805. 
  16. ^ Soeda, Yasuyuki; Toshima, Kazunobu; Matsuma, Shuichi (2003). "Sustainable enzymatic preparation of polyaspartate using a bacterial protease". Biomacromolecules. 4 (2): 193–203. doi:10.1021/bm0200534. 
  17. ^ Gross, Richard A.; Kalra, Bhanu (2002). "Biodegradable Polymers for the Environment". Science. 297 (5582): 803–807. Bibcode:2002Sci...297..803G. doi:10.1126/science.297.5582.803. PMID 12161646. 
  18. ^ Hasson, David; Shemer, Hilla; Sher, Alexander (2011). "State of the Art of Friendly "Green" Scale Control Inhibitors: A Review Article". Industrial & Engineering Chemistry Research. 50 (12): 7601–7607. doi:10.1021/ie200370v. 
  19. ^ Zahuriaan-Mehr, M. J.; Pourjavadi, A.; Salimi, H.; Kurdtabar, M. (2009). "Protein- and homo poly(amino acid)-based hydrogels with super-swelling properties". Polymers for Advanced Technologies. 20 (8): 655–671. doi:10.1002/pat.1395. 
  20. ^ Thombre, Sunita M.; Sarwade, Bhimaro D. (2005). "Synthesis and Biodegradability of Polyaspartic Acid: A Critical Review" (PDF). Journal of Macromolecular Science, Part A. 42 (9): 1299–1315.