latexes

Latexes are colloidal dispersions of polymer particles in water. They can be derived from natural sources, especially the sap of certain plants like Hevea brasiliensis, or produced synthetically by polymerizing monomers in water. Natural rubber latex is a milky suspension of polyisoprene particles containing stabilizers and proteins; synthetic latexes cover a wide range of polymers such as styrene–butadiene, polyacrylates, vinyl polymers, and polyurethane.

In production, latexes are formed by emulsion polymerization, where monomers are emulsified and polymer chains grow as droplets stabilized by surfactants and protective colloids. The resulting dispersion typically contains 30–60% polymer solids and small particles in the submicron to micron range. To use, latexes are stabilized and sometimes coagulated or dried; film formation occurs when water evaporates and polymer droplets fuse to form a continuous film.

Common natural rubber latex is used in medical gloves and various consumer products; synthetic latexes include styrene–butadiene latex (SBR), nitrile butadiene rubber latex (NBR), acrylic latex, vinyl acetate–ethylene (VAE) latex, and polyurethane latex. Applications span paints, coatings, adhesives, textile coatings, paper coatings, and molded or coated items such as gloves, balloons, and coatings for fibers.

Properties and processing: upon drying, coalescence forms a continuous film; some latex systems are vulcanized or crosslinked to improve elasticity and chemical resistance. Particle size, solids content, and additives influence strength, elasticity, barrier properties, and water resistance.

Safety and environment: natural latex can trigger allergic reactions in some people due to residual proteins, leading to the use of alternative synthetic latexes such as nitrile or neoprene for certain products. Waste management focuses on preventing contamination of water and soil, with biodegradability varying by polymer type.