Styrene maleic anhydride
Encyclopedia
Styrene maleic anhydride, also known as SMA or SMAnh, is a synthetic polymer
that is built-up of styrene and maleic anhydride
monomers. The monomers are almost perfectly alternating, making it an alternating copolymer. It is formed by a radical polymerization
, 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 dispersions.
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 broad range of applications. SMA polymers with a high molecular weight 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 or the heat resistancy 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, and coatings. The specific reactivity of SMA makes it a suitable agent for compatibilizing normally incompatible polymers (e.g. ABS/PA blends).
(Dylark). 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) and Polyscope's Xiran product range covers the area in between (with some overlap; also in impact modified grades). Each of those products have their own specific features.
(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
, 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 methods of male contraception: condom
s or vasectomies
.
More information can be found on SMA in reproductive applications at
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
that is built-up of styrene and maleic anhydride
Maleic anhydride
Maleic anhydride is an organic compound with the formula C2H22O. It is the acid anhydride of maleic acid and in its pure state it is a colourless or white solid with an acrid odour....
monomers. The monomers are almost perfectly alternating, making it an alternating copolymer. It is formed by a radical polymerization
Radical polymerization
Free radical polymerization is a method of polymerization by which a polymer forms by the successive addition of free radical building blocks. Free radicals can be formed via a number of different mechanisms usually involving separate initiator molecules...
, using an organic peroxide
Organic peroxide
Organic peroxides are organic compounds containing the peroxide functional group . If the R' is hydrogen, the compound is called an organic hydroperoxide. Peresters have general structure RCOOR. The O-O bond easily breaks and forms free radicals of the form RO·...
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 dispersions.
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 broad range of applications. SMA polymers with a high molecular weight 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 or the heat resistancy to heat-boost other polymers materials like ABS
Acrylonitrile butadiene styrene
Acrylonitrile butadiene styrene is a common thermoplastic. Its melting point is approximately 105 °C ....
or PVC
PVC
Polyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter, a small, flexible tube placed into a peripheral vein in order to administer medication or fluids...
. The solubility of SMA in alkaline solutions makes it suitable for various applications in the field of sizings (paper), binders, and coatings. The specific reactivity of SMA makes it a suitable agent for compatibilizing normally incompatible polymers (e.g. ABS/PA blends).
SMA producers
There are only a few commercial suppliers of SMA polymers. The major producers are Polyscope Polymers (Xiran), Sartomer (SMA), and Nova ChemicalsNOVA Chemicals
NOVA Chemicals Corporation is a plastics and chemical company headquartered in Calgary, Alberta, with Executive Offices in the Pittsburgh suburb of Moon Township, Pennsylvania and Lambton County, Ontario. It was founded in 1954 as Alberta Gas Trunk Lines and was later renamed to NOVA Corporation...
(Dylark). 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) and Polyscope's Xiran product range covers the area in between (with some overlap; also in impact modified grades). Each of those products have their own specific features.
SMA and male contraception (RISUG)
SMA can be combined with the solvent dimethylsulfoxide (DMSO) in an application known as reversible inhibition of sperm under guidanceReversible inhibition of sperm under guidance
Reversible inhibition of sperm under guidance , formerly referred to as the synthetic polymer styrene maleic anhydride , is the development name of a male contraceptive developed at IIT Kharagpur in India by Dr. Sujoy K Guha. Phase III clinical trials are underway in India, slowed by insufficient...
(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
Vas deferens
The vas deferens , also called ductus deferens, , is part of the male anatomy of many vertebrates; they transport sperm from the epididymis in anticipation of ejaculation....
, 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 methods of male contraception: condom
Condom
A condom is a barrier device most commonly used during sexual intercourse to reduce the probability of pregnancy and spreading sexually transmitted diseases . It is put on a man's erect penis and physically blocks ejaculated semen from entering the body of a sexual partner...
s or vasectomies
Vasectomy
Vasectomy is a surgical procedure for male sterilization and/or permanent birth control. During the procedure, the vasa deferentia of a man are severed, and then tied/sealed in a manner such to prevent sperm from entering into the seminal stream...
.
More information can be found on SMA in reproductive applications at