Polyurethane-48 is an inorganic chemical compound, a segmented block copolymer derived from urethane and synthesised from isocyanates.

The name describes the structure of the molecule:

• "Polyurethane" is a term that describes a class of polymers widely used in various applications due to their versatility and desirable properties such as durability, flexibility and abrasion resistance and temperature variations.
• "-48" is a reference to the specific type or grade of polyurethane, which can be characterized by such factors as the types of isocyanates and polyols used, their relative amounts, and the presence of any additives. . This is a designation used to differentiate different molecular structures or variants of the polymer. In cosmetic chemistry, these numbers can help formulators identify specific characteristics or behaviors of a given ingredient, particularly when a chemical family has multiple derivatives or forms.
  
  

Significant substances used in the production method:

hexanediol, neopentyl glycol, adipic acid, isophorone diisocyanate, isophorone diamine, sodium N-(2-aminoethyl)-3-aminoethanesulfonic acid monomers.

To exemplify:

Description of the raw materials used in production:

• Diisocyanates - Diisocyanates are chemical compounds used as reagents in the synthesis of polyurethane. Common diisocyanates used in the production include toluene diisocyanate (TDI) or diphenylmethane diisocyanate (MDI). These diisocyanates react with polyols to form the polyurethane structure.
• Polyols - Polyols are chemical compounds containing hydroxyl (OH) groups that react with diisocyanates to form the polyurethane structure. Common polyols used in the production include polyether polyols or polyester-based polyols. These polyols impart elasticity and strength.
• Crosslinking agents - Crosslinking agents are used to provide this polyurethane with its three-dimensional structure and desired physical properties. Crosslinking agents can be physical crosslinking agents, such as chemical crosslinkers like trifunctional polyols or crosslinking catalysts.

The synthesis process takes place in several stages:

• Preparation of monomers by reaction of a diisocyanate with a polyol. Diisocyanate is a compound that contains two groups of isocyanate (-NCO), and polyol is a molecule with multiple hydroxyl groups (-OH).
• Polymerization. Monomers react to form polyurethane by reacting diisocyanate isocyanate groups with polyol hydroxyl groups. This reaction forms urethane bonds (-NHCOO-) and causes the formation of polyurethane polymer.
• Processing to form the desired product with various techniques such as molding, casting or extrusion, depending on the desired shape of the final product.

It appears as a white powder or colorless liquid.

What it is used for and where

Polyurethanes can be used in a wide range of applications due to their versatility. They can be flexible or rigid and are used in products such as foams, coatings, adhesives, sealants and elastomers.

Cosmetics

Film-forming agent. It produces a continuous ultra-thin film with an optimal balance of cohesion, adhesion and stickiness on the skin or hair to counteract or limit damage from external phenomena such as chemicals, UV rays and pollution.

Safety

Urethane (also called ethyl carbamate) is a by-product of fermentation and is considered a genotoxic agent.

Polyurethanes are rather complex, inert and biostable materials that are also used in biomedical applications. They are typically synthesised by the reaction of a glycol or polyol with polyisocyanate or diisocyanate. It is known that exposure to isocyanates can cause asthma, contact allergies, conjunctival and skin irritation. However, a study by the Cosmetic Ingredient Review Expert Panel in 2017 found that the rates of harmful residues are not significant for human health.

References__________________________________________________________________________

Puiggené, Òscar, et al. "Extracellular degradation of a polyurethane oligomer involving outer membrane vesicles and further insights on the degradation of 2, 4-diaminotoluene in Pseudomonas capeferrum TDA1." Scientific Reports 12.1 (2022): 2666.

Abstract. The continuing reports of plastic pollution in various ecosystems highlight the threat posed by the ever-increasing consumption of synthetic polymers. Therefore, Pseudomonas capeferrum TDA1, a strain recently isolated from a plastic dump site, was examined further regarding its ability to degrade polyurethane (PU) compounds. The previously reported degradation pathway for 2,4-toluene diamine, a precursor and degradation intermediate of PU, could be confirmed by RNA-seq in this organism. In addition, different cell fractions of cells grown on a PU oligomer were tested for extracellular hydrolytic activity using a standard assay. Strikingly, purified outer membrane vesicles (OMV) of P. capeferrum TDA1 grown on a PU oligomer showed higher esterase activity than cell pellets. Hydrolases in the OMV fraction possibly involved in extracellular PU degradation were identified by mass spectrometry. On this basis, we propose a model for extracellular degradation of polyester-based PUs by P. capeferrum TDA1 involving the role of OMVs in synthetic polymer degradation....esterase activity has been previously identified to act on polyester-based polyurethane 48,69,70 ...

Mills, Jamie. "Trends, tips and top products: hair care." South African Pharmaceutical and Cosmetic Review 43.1 (2016): 16-19.