Polyisobutylene succinic anhydride

The polyispbptylenes (PIB) having molecular weights ranging from 1000 to 2000 are substituted by maleic anhydride, and the polyisobutylene succinic anhydride (PIBSA) formed is neutralized by a polyethylene-polyamine as indicated in Figure 9.10. 

Lubrication oil additives represent another important market segment for maleic anhydride derivatives. The molecular stmctures of importance are adducts of polyalkenyl succinic anhydrides (see Lubrication and lubricants). These materials act as dispersants and corrosion inhibitors (see Dispersants Corrosion and corrosion control). One particularly important polyalkenyl succinic anhydride molecule in this market is polyisobutylene succinic anhydride (PIBSA) where the polyisobutylene group has a molecular weight of 900 to 1500. Other polyalkenes are also used. Polyalkenyl succinic anhydride is further derivatized with various amines to produce both dispersants and corrosion inhibitors. Another type of dispersant is a polyester produced from a polyalkenyl succinic anhydride and pentaerythritol [115-77-5]. 

One final example of SCF fractionation of polymers is given in this section to show the breadth of this technology. The polymer tested in a study by Krukonis (1983c) is a polyisobutylene-succinic anhydride copolymer surfactant used in engine lubricants. The surface-active ends of the polymer complex to... 

Table 9.34 Molecular Weight Analysis of Polyisobutylene-Succinic Anhydride Copolymer Fractions...

Poly(ethylene-co-vinyl acetate)-ethylene-vinyl acetate system, 80 Polyisobutylene, 66, 192 surfactant, 278-279 Polyisobutylene-succinic anhydride copolymer fractions, 279 Polymers... 

Harrison [4] prepared poly(isobutylene-g-succinic anhydride) by reacting a 1 1 mole ratio of polyisobutene/maleic anhydride using di-t-butylperoxide as catalyst where the ratio of di-t-butylperoxide/polyisobutene was 0.05 1, respectively. In this procedure polyisobutylene had a Mn of roughly 2300 daltons while the product had a SAP number of 26.2 mg for the KOH/g sample. Poly (isobutylene-g-succinic anhydride) has also been prepared in the simultaneous chlorination/maleation process described by Barini [5]. 

Dispersants, on the other hand, utilize longer alkyl chains, mainly polyisobutylene of 500-2000 Mn. For succinimide-types, these are converted to the succinic anhydride intermediates (or succans) by reaction with maleic... 

Tessier and Marechal prepared a-methyl-succinic anhydride) oligoisobutylene by reacting a-methyl-co-chlorooligoisobutylene (CIB) with maleic anhydride. When CIB is heated at 200 C, dehydrochlorination takes place which results in the formation of endo and exo double bonds (Scheme 8) while only exo double bonds are able to react with maleic anhydride (Scheme 9, where PIB is the polyisobutylene chain). 

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