Polymers Carbodiimide

Modification of cellular polymers by incorporating amide, imide, oxa2ohdinone, or carbodiimide groups has been attempted but only the urethane-modified isocyanurate foams are produced in the 1990s. PUIR foams often do not require added fire retardants to meet most regulatory requirements (34). A typical PUIR foam formulation is shown in Table 6. 

Ionic polymers are also formulated from TDI and MDI (43). Poly(urethane urea) and polyurea ionomers are obtained from divalent metal salts of /)-aminohen2oic acid, MPA, dialkylene glycol, and 2,4-TDI (44). In the case of polyureas, the glycol extender is omitted. If TDI is used in coatings apphcations, it is usually converted to a derivative to lower the vapor pressure. A typical TDI prepolymer is the adduct of TDI with trimethyl olpropane (Desmodur L). Carbodiimide-modified MDI offers advantages in polyester-based systems because of improved hydrolytic stabihty (45). Moisture cure systems based on aromatic isocyanates are also available. 

In conclusion, IR analysis of polymer/additive extracts before chromatographic separation takes advantage mainly of straightforward transmission measurements. Without separation it is often possible to make class assignments (e.g. in the reported examples on plasticisers and carbodiimide hydrolysis stabilisers) it may eventually be necessary to use multivariate techniques. Infrared detection of chromatographic effluents is dealt with in Chapter 7. 

Carboxylated silica particles may be coupled with amine-containing ligands, such as proteins, using a carbodiimide reaction with EDC. A similar protocol to that previously described for coupling to carboxylate polymer particles may be used. The following protocol is based on the method of Zhao et al. (2004), which was used for immobilizing monoclonal antibodies to E. coli 0157. 

Such carbonyls may be further oxidized using potassium permanganate (KMnO and perchloric acid (HCIO4) to convert all of these groups into carboxylic acids. Once functionalized in this manner, the nanotubes can be fully dispersed in aqueous systems. Kordas et al. (2006) used these derivatives to print nanotube patterns on paper or polymer surfaces to create conductive patterns for potential use in electronic circuitry. The carboxylates also may be used as conjugation sites to link other ligands or proteins to the nanotube surface using a carbodiimide reaction as previously discussed (Section 1, this chapter Chapter 2, Section 1.11 Chapter 3, Section 1). 

Figure 25.14 An amine derivative of dextran may be prepared through a two-step process involving the reac-tion of chloroacetic acid with the hydroxyl groups of the polymer to create carboxylates. Next, ethylene diamine is coupled in excess using a carbodiimide-mediated reaction to give the primary amine functional groups.

The carboxymethyl-dextran derivative may be used to couple amine-containing molecules by the carbodiimide reaction. Heindel et al. (1994) prepared the lactone derivative of carboxymethyl-dextran by refluxing for 5 hours in toluene or other anhydrous solvents. The lactone derivative is highly reactive toward amine-containing molecules, thus creating a preactivated polymer for conjugation purposes. 

Figure 25.18 An amine-derivative of dextran may be coupled with iodoacetic acid using a carbodiimide reaction to produce a sulfhydryl-reactive iodoacetamide polymer.

Scheme 7.103 Amide synthesis utilizing polymer-bound carbodiimide.

Fig. 5.8 Examples of polymers grafted from nanocarbons, (a) An ATRP initiator covalently attached to RGO via nitrene and carbodiimide chemistry was used for the growth of poly(2-(ethyl (phenyl)amino)ethyl-methacrylate). (b) A RAFT chain transfer agent is covalently attached to GO prior to polymerization of vinylcarbozole.

ROMP polymers bearing acid chloride, phosphonate, carbodiimide, phosphonyl chloride, and phosphine groups have been used as platforms in phase-switching, sequestration, capture-release, and soluble support applications. 

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