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The development of polymeric scale inhibitors began in the mid‑20th century as industries sought alternatives to small‑molecule phosphonates and other thresholds inhibitors.
Polycarboxylates (e.g., polyacrylic acid, PAA) provided effective dispersion of particulate matter and some scale inhibition through adsorption and growth‑site blocking, but their performance against certain scales (e.g., barium sulfate, gypsum) and their stability in oxidizing environments was limited. Incorporation of phosphorus functionality into polymer backbones produced hybrid materials—phosphino polycarboxylic acids—combining advantages of phosphonate/phosphinate chemistries (strong calcium binding and threshold inhibition) with polymeric properties (surface adsorption, steric stabilization, and retention characteristics).
CAS number(s): 71050-62-9, 110224-99-2
Common synonyms / trade names: Phosphino polycarboxylic acid, Phosphino carboxylic acid, Phosphino-carboxylic acid copolymer (PCAC), Phosphino-polycarboxylic acid
Over decades PPCA variants were optimized for oilfield squeeze treatments, cooling‑water systems, and membrane pretreatment, and numerous commercial grades and copolymer compositions were developed.
PPCA encompasses a family of copolymers containing repeating units bearing carboxylic acid groups (from monomers such as acrylic acid/2‑propenoic acid or maleic acid derivatives) and phosphorus‑bearing units (from comonomers such as sodium hypophosphite, phosphinic acid derivatives, or by post‑functionalization that introduces phosphonate/phosphinate groups). Generic backbone examples include:
Poly(acrylic acid‑co‑sodium hypophosphite) (a common simplified description)
Poly(methacrylic acid‑co‑phosphinate) or poly(acrylic acid‑co‑phosphonate) depending on chemistry
Structural representation is typically non‑stoichiometric and shown in repeat‑unit form.
The phosphorus functional group can be present as P(III) phosphinate (—P(O)(OH)R) or as P(V) phosphonate (—PO₃H₂) depending on synthetic route; the oxidation state and exact functionality govern coordination chemistry and hydrolytic/oxidative stability.
Because PPCA materials are copolymers with variable composition and molecular weight, they are best described as polymeric dispersants/inhibitors rather than discrete molecular species — hence the presence of multiple CAS numbers in commercial databases for particular grades or definitions.
Nomenclature, CAS registry issues, and trade names
Different suppliers and registries may list differing CAS numbers and synonyms for commercial PPCA products.
Examples encountered in chemical supplier catalogs include CAS 71050‑62‑9 and 110224‑99‑2; these correspond to specific registered formulations or representative polymer compositions and not to a single universal molecular entity.
Synonyms include PCA, PCAC, PPCA, POCA, and marketing/trade names vary by manufacturer.
When specifying a raw material for procurement, it is essential to refer to the supplier's technical data sheet (TDS), specification of active content, molecular weight range, and recommended applications rather than relying solely on CAS registry alone.
Synthesis and manufacturing routes
Direct copolymerization
A common route is free‑radical copolymerization of acrylic acid (or its sodium salt) with a phosphorus‑containing vinyl comonomer or with an organophosphorus‑containing monomer generated in situ (e.g., via addition of sodium hypophosphite under conditions that enable grafting). Initiators (azobisisobutyronitrile, persulfates), chain transfer agents, temperature control, and solvent/water media are used to control molecular weight and composition. Monomer feed ratio controls the P:COOH content.
Post‑functionalization
An alternative is to prepare a polyacrylic backbone and introduce phosphorus functionality via addition reactions (e.g., Michael‑type additions, Mannich reactions with hypophosphorous derivatives) or phosphorylation of pendant groups.
This allows more targeted placement of phosphorus moieties but usually increases processing steps and cost.
Polycondensation / modified routes
Less common routes involve condensation chemistry where phosphorus acids react with unsaturated polymers to graft phosphorus groups.
Manufacturing scale processes emphasize reproducibility, control of residual monomers, and neutralization state (Na+ salt vs. free acid).
Molecular weight control
Molecular weight (Mw, Mn), polydispersity index (PDI), and chain architecture (linear, slightly branched) are controlled by initiator concentration, chain transfer agents (e.g., mercaptans), solvent, and reaction time.
Grades optimized for squeeze treatments often have specific molecular‑weight windows to balance inhibition potency and retention/release behavior in porous formations.
Molecular weight, polydispersity and formulation grades
Commercial PPCA products are available in solution form (typical solids 20–50% w/w) with Mw typically in the low‑to‑moderate polymer range (≈500–5000 Da for some oilfield grades up to tens of thousands for certain dispersants).
PDI influences performance: narrower distributions produce more predictable adsorption and return curves in squeeze applications, while broader distributions may improve certain dispersion tasks. Additives (e.g., biocides, corrosion inhibitors, sequestrants) and neutralization (sodium/potassium salts) alter solution behavior.
Physicochemical properties
Acid‑base behavior: multiple carboxylate groups and phosphorus acidic groups render PPCA strongly anionic in neutral to alkaline pH.
Degree of ionization depends on pH and ionic strength.
Solubility: highly water‑soluble as free acid neutralized to sodium salts; solubility decreases with multivalent cation concentration due to cross‑linking/complexation.
Complexation: phosphorus and carboxylate groups chelate divalent cations (Ca²⁺, Mg²⁺, Ba²⁺), affecting nucleation and growth processes.
Thermal and oxidative stability: PPCA often demonstrates improved thermal stability relative to simple phosphonates; oxidative chlorine tolerance is commonly cited as superior to some organophosphonates, making PPCA suitable in chlorinated cooling systems.
However, detailed stability depends on phosphorus oxidation state and backbone chemistry.
SAFETY INFORMATION ABOUT PHOSPHINO POLYCARBOXYLIC ACID COPOLYMER
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
