Styrene maleic anhydride (SMA or SMAnh) is a synthetic

polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

that is built-up of

styrene Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...

and

maleic anhydride Maleic anhydride is an organic compound with the formula C2H2(CO)2O. It is the acid anhydride of maleic acid. It is a colorless or white solid with an acrid odor. It is produced industrially on a large scale for applications in coatings and pol ...

monomers In chemistry, a monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization. Classification Mo ...

. The monomers can be almost perfectly alternating, making it an alternating

copolymer In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization. Copolymers obtained from the copolymerization of two monomer species are some ...

, but (random) copolymerisation with less than 50% maleic anhydride content is also possible. The polymer is formed by a

radical polymerization In polymer chemistry, free-radical polymerization (FRP) is a method of polymerization by which a polymer forms by the successive addition of free-radical building blocks ( repeat units). Free radicals can be formed by a number of different mechani ...

, using an organic peroxide as the initiator. The main characteristics of SMA copolymer are its transparent appearance, high heat resistance, high dimensional stability, and the specific reactivity of the anhydride groups. The latter feature results in the solubility of SMA in alkaline (water-based) solutions and dispersion. SMA is available in a broad range of molecular weights and maleic anhydride (MA) contents. In a typical combination of those two properties, SMA is available as a crystal clear granule that can be used in a wide variety of applications. SMA polymers with a high

molecular weight A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...

are widely used in engineering plastic applications, normally in the impact modified and optional glass fibre filled variants. Alternatively, SMA is applied using its transparency in combination with other transparent materials like

PMMA PMMA may refer to: * para-Methoxymethamphetamine, a stimulant drug * Philippine Merchant Marine Academy The Philippine Merchant Marine Academy ( fil, Akademiya sa Bapor Pangkalakalan ng Pilipinas) also referred to by its acronym PMMA) is a ma ...

or the heat resistance to heat-boost other polymers materials like ABS or PVC. The solubility of SMA in alkaline solutions makes it suitable for various applications in the field of sizings (paper), binders, dispersants and coatings. The specific reactivity of SMA makes it a suitable agent for compatibilizing normally incompatible polymers (e.g. ABS/PA blends) or cross-linking. The glass transition temperature of Styrene maleic anhydride is 130 - 160 °C.

SMA producers

There are only a few commercial suppliers of SMA polymers. The three major producers are Solenis (Scripset), Polyscope Polymers (Xiran), Sartomer (SMA).

Nova Chemicals NOVA Chemicals Corporation is a Canadian petrochemical company that has been in operation since 1954. NOVA was formed as provincial crown corporation called the Alberta Gas Trunk Line Company Limited to manage Alberta's natural gas collection sy ...

(Dylark) is no longer produced. While the Sartomer product range covers low molecular weight products with high MA contents (and sometimes chemically modified), the Nova materials are high molecular products with low MA content (and mainly impact modified). Polyscope's Xiran product range covers the full spectrum of SMA polymers, including chemically modified types. Each of those products have their own specific features.

SMA and male contraception (RISUG)

SMA can be combined with the solvent

dimethylsulfoxide Dimethyl sulfoxide (DMSO) is an organosulfur compound with the formula ( CH3)2. This colorless liquid is the sulfoxide most widely used commercially. It is an important polar aprotic solvent that dissolves both polar and nonpolar compounds and ...

(DMSO) in an application known as reversible inhibition of sperm under guidance (RISUG). The process is under phase III clinical trials in India and is a non-surgical method of male sterilization that is inexpensive, highly effective, and reversible. It involves an injection of the solution into each of the patient's

Vas deferens The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube ...

, which forms a layer around the vas walls partially (but not completely) blocking the flow of sperm cells. As cells pass by the substance, they are rendered inactive. If approved for widespread application, it could provide an alternative to the current two major methods of male contraception: condoms or vasectomies.

References

References list for RISUG
{{Plastics Copolymers