POLY(ACRYLIC ACID), SODIUM SALT

• CAS: 76774-25-9
• Catalog Number: ACM76774259-3
• Category: Main Products
• Molecular Weight: 462.4g/mol
• Molecular Formula: C21H27NaO10
• Synonyms: opanediyldi-2-propenoateandsodium2-propenoate;poly(acrylicacid)partialsodiumsalt
• IUPAC Name: sodium;2,2-bis(prop-2-enoyloxymethyl)butyl prop-2-enoate;prop-2-enoate;prop-2-enoic acid
• SMILES: CCC(COC(=O)C=C)(COC(=O)C=C)COC(=O)C=C.C=CC(=O)O.C=CC(=O)[O-].[Na+]
• InChI: InChI=1S/C15H20O6.2C3H4O2.Na/c1-5-12(16)19-9-15(8-4,10-20-13(17)6-2)11-21-14(18)7-3;2*1-2-3(4)5;/h5-7H,1-3,8-11H2,4H3;2*2H,1H2,(H,4,5);/q;;;+1/p-1
• InChI Key: NZZHEJIHHYZFLN-UHFFFAOYSA-M
• Appearance: White to Off White powder
• Application: The purpose of POLY(ACRYLIC ACID), SODIUM SALT, commonly known as sodium polyacrylate, is to serve as a highly effective absorbent for aqueous-based spills, making it invaluable in various consumer and industrial applications. This compound is a sodium salt of polyacrylic acid, characterized by its macromolecular structure composed of repeating sodium acrylate units. Notably, sodium polyacrylate can absorb 200 to 300 times its mass in water, a property that allows it to function as an efficient retention and slow-release aid for water. It acts as an anionic polyelectrolyte with negatively charged carboxylic groups, enhancing its ability to bind with substances. Widely used in the industry, its primary form is the sodium-neutralized version, though other variants like potassium, lithium, and ammonium salts also exist. In addition to its absorbing capabilities, it functions as a sequestering agent in detergents, where it binds hard water elements such as calcium and magnesium to improve the efficiency of surfactants.
• Complexity: 480
• Covalently-Bonded Unit Count: 4
• Exact Mass: 462.150191g/mol
• Formal Charge: 0
• H-Bond Acceptor: 10
• H-Bond Donor: 1
• Heavy Atom Count: 32
• Monoisotopic Mass: 462.150191g/mol
• Rotatable Bond Count: 15

Case Study

Poly(acrylic acid) Sodium Salt as a Polyanion for Polyelectrolyte Complex Coacervation with Poly(allylamine) Hydrochloride

Chollakup, Rungsima, et al. Macromolecules 46.6 (2013): 2376-2390.

Poly(acrylic acid) sodium salt (PAANa) serves as a weak polyanion that forms electrostatic complexes with the cationic poly(allylamine) hydrochloride (PAH). Systematic variation of PAANa molecular weight, mixing ratio, and NaCl concentration enables controlled formation of precipitates, fluid coacervates, or homogeneous solutions.
Experimental Protocol: PAANa of four molecular weights (Pw = 25, 70, 417, 695) and PAH (Pw = 765) were mixed at total polymer concentration 0.05 wt% in water with 0-3000 mM NaCl. Turbidity, optical microscopy, and centrifugation distinguished precipitate, coacervate, or solution phases.
Performance Evaluation: Salt-free systems always formed precipitates. Increasing NaCl induced transitions: precipitate → coacervate → solution. The critical salt concentration for coacervate formation was above 50 mM for PAANa-25, 100 mM for PAANa-70/417, and 200 mM for PAANa-695. Coacervate dissolution required 300-400 mM (PAANa-25), 800-1000 mM (PAANa-70), 1200-1500 mM (PAANa-417), and 2500-3000 mM (PAANa-695). Non-stoichiometric polyanion/polycation ratios narrowed the coacervate regime. Higher PAANa molecular weight expanded coacervate stability.
Conclusion: PAANa chain length critically controls salt-induced phase behavior, enabling tunable coacervate formation for applications in encapsulation or adhesion.

Sodium Polyacrylate as a Polymer Modifier for Bentonite to Enhance Chemical Resistance in Hydraulic Barriers

Yu, Chuang, et al. Journal of Cleaner Production 213 (2019): 242-250.

Sodium polyacrylate serves as an anionic polymer modifier that significantly improves the chemical resistance and hydraulic performance of bentonite through interlayer encapsulation and formation of a three-dimensional network structure, enabling stable permeability in saline and acidic environments.
Fabrication Process: Calcium bentonite was first treated with sodium carbonate, then mixed with acrylic acid, NIPA (crosslinker), and potassium persulfate (initiator). The slurry was polymerized at 75 °C with a solid-to-liquid ratio of 1:2. The resulting sodium polyacrylate bentonite (SPB) was dried at 105 °C.
Performance Evaluation: SPB showed a free swell index (FSI) of 50 mL/2g in deionized water, double that of raw bentonite (25 mL/2g). The hydraulic conductivity (k) of SPB in deionized water was 1.2 × 10^-11 m/s, one order of magnitude lower than raw bentonite (1.61 × 10^-10 m/s). In 40 mM Pb(NO3)2 solution, k of SPB remained 2.68 × 10^-11 m/s, while raw bentonite increased to 2.42 × 10^-8 m/s. Cation exchange capacity (CEC) increased from 62.06 to 96.1 meq/100g. FTIR confirmed new COO⁻ peaks (1575, 1414 cm^-1). SEM showed a change from lamellar stacking to isolated cavity structures.
Conclusion: Sodium polyacrylate modification provides a durable barrier material with superior chemical resistance for landfill and environmental applications.

Sodium Polyacrylate as a Stabilizer in the Electrochemical Synthesis of Silver Nanoparticles

Kuntyi, О. I., et al. Colloid and Polymer Science 297.5 (2019): 689-695.

Sodium polyacrylate (NaPA) serves as an anionic polymeric stabilizer that enables the controlled electrochemical synthesis of small silver nanoparticles (AgNPs) under alternating current polarity, where the polyacrylate anion complexes Ag+ ions and prevents anode passivation.
Experimental Protocol: Two silver electrodes were immersed in aqueous NaPA solutions (0.5-20 g/L) at pH 8-9.5 and 40-60 °C. Electrolysis was performed at 6 V with polarity reversal at 1 Hz under stirring. Cyclic voltammetry assessed electrode behavior. UV-vis spectroscopy monitored nucleation (~350 nm) and growth (490-530 nm). TEM determined particle size.
Performance Evaluation: Anodic current increased linearly with NaPA concentration and temperature (5-7% per 10 °C). The observed nucleation rate (rN) and growth rate (rG) depended on NaPA concentration with formal reaction orders of 1.7 and 2.5, respectively. Activation energies were 1.5 ± 2 kJ/mol (nucleation) and 23 ± 12 kJ/mol (growth), indicating diffusion-controlled processes. TEM showed AgNPs with mean diameters of 1.5-4.1 nm. Higher NaPA concentrations increased polydispersity by promoting growth over nucleation (rN/rG decreased from 2.8 to 1.0).
Conclusion: Sodium polyacrylate enables green, diffusion-controlled electrochemical synthesis of ultrasmall silver nanoparticles with tunable size and size distribution.