Oligomeric carbodiimides polymers

Oligomeric carbodiimides are efficient stabilizers for polyesters or polyester containing polymers. 

In Table 12.1, the carbodiimides and oligomeric carbodiimides used in the stabilization of polyester based polymers are listed. ... 

When the less hindered 2,4-tolylene diisocyanate is reacted with a phospholene oxide catalyst linear oligomeric carbodiimides are obtained which have been reacted with a variety of nucleophiles to give poly(ureas), poly(acyl ureas), poly(formamidines) and poly-(guanidines) by addition across the N=C=N group. Also, reaction of the oligomeric carbodiimides with acrylic or methacrylic acid affords linear polymers, which can be further polymerized by free-radical type processes. Also, reaction of the carbodiimide oligomers obtained from 2,4-TDI with adipic acid in DMF produces a polyureid. ... 

Table 12.1 Carbodiimides and Oligomeric Carbodiimides Used as Stabilizers for Polyester Based Polymers...

Oligomeric carbodiimides derived from sterically hindered aromatic diisocyanates are used as stabilizers for polyester based polymers because the carbodiimide groups in the oligomers, or in sterically hindered diisocyanates, mop up HCl, which catalyzes the depolymerization of polyesters. The carbodiimide stabilizers are commercially available under the tradename Stabaxol from Rhein Chemie, a subsidiary of Bayer. 

Oligomeric carbodiimides are useful stabilizers for ester based polymers, such as polyesters, polyester based polyurethanes, polyether based polyurethanes, polyether based poly(urethane ureas) and polycarbonates. The scavenging of carboxyl end groups or carboxyl groups, generated in the hydrolysis of polyesters, with carbodiimide prevents hydrolysis of the polymers caused by the catalytic effect of the carboxyl groups. Neumann... 

The aza-Wittig reaction is also used to form polymers with pendant carbodiimide groups. For example, reaction of the polymeric azide 31 with benzyl isothiocyanate and triphenylphosphine gives the corresponding carbodiimide 32, a precursor for oligomeric guanidines." ... 

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