Polyisobutene (polyisobutylene) is a class of organic polymers prepared by polymerization of

isobutene Isobutylene (or 2-methylpropene) is a hydrocarbon with the chemical formula . It is a four-carbon branched alkene (olefin), one of the four isomers of butylene. It is a colorless flammable gas, and is of considerable industrial value. Productio ...

. The polymers often have the formula Me₃C H₂CMe₂sub>nH (Me = CH₃). They are typically colorless gummy solids.

Cationic polymerization In polymer chemistry, cationic polymerization is a type of Chain growth polymerisation, chain growth polymerization in which a cationic initiator transfers charge to a monomer, which then becomes reactive. This reactive monomer goes on to react si ...

, initiated with a strong Brønsted or

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any ...

, is the typical method for its production. The

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

(MW) of the resulting polymer determines the applications. Low MW polyisobutene, a mixture of

oligomer In chemistry and biochemistry, an oligomer () is a molecule that consists of a few repeating units which could be derived, actually or conceptually, from smaller molecules, monomers.Quote: ''Oligomer molecule: A molecule of intermediate relativ ...

s with M_ns of about 500, is used as

plasticizer A plasticizer ( UK: plasticiser) is a substance that is added to a material to make it softer and more flexible, to increase its plasticity, to decrease its viscosity, and/or to decrease friction during its handling in manufacture. Plasticizer ...

s. Medium and high MW polyisobutenes, with M_n ≥ 20,000, are components of commercial

adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advantage ...

s.{{cite encyclopedia , author1=Kenneth S. Whiteley , author2=T. Geoffrey Heggs , author3=Hartmut Koch , author4=Ralph L. Mawer , author5=Wolfgang Immel , title=Polyolefins , encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry , year=2005 , publisher=Wiley-VCH , place=Weinheim , doi=10.1002/14356007.a21_487

References

Organic polymers

See also

References