Is polysuccinimide water-soluble?

No — it is essentially water-insoluble. For aqueous use it is hydrolysed to sodium polyaspartate.

Yes, via its polyaspartate derivative, which is why it is used as a greener alternative to some phosphonates and polyacrylates.

Why does PSI have several CAS numbers?

It is registered variably by molecular weight and synthesis route, so the exact CAS and molecular weight depend on the grade.

How is polysuccinimide converted to polyaspartate?

By alkaline hydrolysis. Published routes add sodium hydroxide to a PSI slurry and hold it warm, typically somewhere between 65 and 90 °C at alkaline pH, until the imide rings open to the sodium polyaspartate salt. Conditions vary with the molecular weight and the colour specification being targeted.

Why buy PSI rather than polyaspartate directly?

Mostly logistics. PSI is a dry powder, so you are not shipping and storing water; polyaspartate is normally sold as an aqueous solution. Formulators who hydrolyse in-house can also set the degree of conversion and the counter-ion themselves.

Polysuccinimide

CAS 26099-09-2 (C₄H₃NO₂)n

CAS number: 26099-09-2
Formula: (C₄H₃NO₂)n
Molar mass: 97.07 g/mol repeat unit · polymer MW ~1,000–10,000 (up to ~50,000)
Appearance: Beige to light-brown powder; virtually water-insoluble; slowly hydrolyses to polyaspartate.

Polysuccinimide is the anhydrous polyimide that sits one step upstream of polyaspartate. On its own it is a beige, water-insoluble powder with little direct application; hydrolyse it with alkali and it opens into sodium polyaspartate, a biodegradable polycarboxylate that sequesters calcium and disperses scale. That two-stage route is the reason PSI is traded at all — it ships and stores as a dry solid rather than as a dilute polymer solution. Ehlinar supplies water-treatment and cosmetic grades, defined by molecular weight; the polymer carries more than one registered CAS number.

Applications

Water treatmentPrecursor to biodegradable polyaspartate; slow-release scale inhibitor for cooling/boiler water

DetergentsBuilder and anti-redeposition dispersant

Oilfield & agricultureFertilizer-efficiency aid and soil conditioner

Personal careFilm former

Chemical intermediatesChelation / sequestrant intermediate

Grades & packaging

Water-treatment and cosmetic grades are defined by molecular weight and appearance rather than a single assay figure.

25 kg fiber drums/bags
500–1000 kg bulk bags

How we supply

Supplier documentation on request

Certificate of Analysis (CoA), lot-specific where available
Safety Data Sheet (SDS / MSDS)
Technical Data Sheet (TDS)
Certificate of Origin / Certificate of Conformity

Quality assurance

Independent third-party inspection can be arranged on request, with the agency and scope agreed per trade. Representative samples can be requested for qualification, subject to supplier availability. We recommend incoming quality control against the agreed CoA.

Delivery & terms

Quoted on standard Incoterms (e.g. EXW, FOB, CIF, DAP) as agreed per trade. Delivery region, packaging and grade are confirmed per quote.

Documents and services above are subject to supplier availability and confirmed per quote; nothing here is an offer.

Typical / indicative values — not a binding specification

Property	Typical
Molecular weight	~1,000–10,000 (up to ~50,000)
Repeat-unit mass	97.07 g/mol
Water solubility	Virtually insoluble — hydrolyses to polyaspartate

Also known as

PSI · Anhydropolyaspartic acid · Poly[imino(1-oxo-1,2-ethanediyl)] · Polyaspartic-acid (PASP) precursor

Frequently asked questions

Is polysuccinimide water-soluble?: No — it is essentially water-insoluble. For aqueous use it is hydrolysed to sodium polyaspartate.
Is it biodegradable?: Yes, via its polyaspartate derivative, which is why it is used as a greener alternative to some phosphonates and polyacrylates.
Why does PSI have several CAS numbers?: It is registered variably by molecular weight and synthesis route, so the exact CAS and molecular weight depend on the grade.
How is polysuccinimide converted to polyaspartate?: By alkaline hydrolysis. Published routes add sodium hydroxide to a PSI slurry and hold it warm, typically somewhere between 65 and 90 °C at alkaline pH, until the imide rings open to the sodium polyaspartate salt. Conditions vary with the molecular weight and the colour specification being targeted.
Why buy PSI rather than polyaspartate directly?: Mostly logistics. PSI is a dry powder, so you are not shipping and storing water; polyaspartate is normally sold as an aqueous solution. Formulators who hydrolyse in-house can also set the degree of conversion and the counter-ion themselves.

Enquire about Polysuccinimide

Related products

Figures and identifiers here are compiled from public references and provided for general information; they are indicative, not a specification. See all products.