Abstract
This chapter describes ammonia as a reagent or reaction medium for polymers. Ammonia in the liquid or in the supercritical state can be favorably used as a reactant and solvent for polymers if one takes into account the high reactivity. Ammonolysis of polyesters, polycarbonates, and polyamides has been investigated. The stability of polyesters toward ammonlytic cleavage increases in the order fully aromatic, aromatic aliphatic, and aliphatic. Poly(hexamethylene carbonate) can be fractionated by extraction below 100°C and degraded in a controlled manner under supercritical conditions. Aromatic bisphenol-A-polycarbonate is degraded to bisphenol-A and urea already at room temperature. This allows selective degradation of blends and composite materials such as compact disks and car windows. Ammonia is the solvent of choice for silylation of the hydroxyl group containing polymer, especially cellulose and starch with hexamethyldisilazane. Complete silylation as well as controlled silylation with stoichiometric amount of silylating agent has been achieved. An advantage of the new synthesis is that ammonia is the only by-product formed, which allows simple work-up by the evaporation of ammonia. Saccharin as a catalyst is required for complete and controlled partial silylation.
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