Polyurethanes metalated with sodium

George and Barrie have extended their studies of the metallation of polymers to polyurethanes. Poly(ester-urethane)s based on diphenyl methane-4,4-di-iso-cyanate and toluene di-isocyanate were metallated with sodium hydride in THF. Metallation apparently occurs at the urethane link (Scheme 18) and these O... 

The Ford hydroglycolysis process is an example of a combined approach for die depolymerization of PURs. In a reactor, polyurethane foam is reacted with a mixture of water, diethylene glycol, and alkali metal hydroxides at high temperature to form polyols. When sodium hydroxide is added as a catalyst, a cleaner polyol is formed because all of the carbamates and ureas in the product are converted into amines and alcohols by hydrolysis.33... 

A wide range of chemical agents, catalysts and conditions for the glycolysis of unsaturated polyester resins, used in the manufacture of buttons, have been described in a recent patent.34 In addition to different metal acetates, the following compounds have been proposed to be catalytically active in PET glycolysis sodium methylate, sodium ethylate, sodium hydroxide, methane-sulfonic acid, magnesium oxide, barium oxide and calcium oxide. Different applications of the depolymerization products were described, e.g., preparation of fresh unsaturated polyesters by reaction with maleic acid, maleic acid/ phthalic anhydride or maleic anhydride/terephthalic acid or the synthesis of polyurethane resins by reaction with a diisocyanate. 

Sudha et al. (2008) and Dinesh Karthik et al. (2009) reported on the removal of heavy metal cadmium and chrominm from industrial wastewater using chitosan-coated coconut charcoal and chitosan impregnated polyurethane foam, respectively. Adsorption and determination of metal ions such as zinc (11) and vanadium (II) onto chitosan from seawater have been studied (Muzzarelli et al. 1970, Muzzarelli and Sipos 1971, Muzzarelli and Rocchetti 1974). Adsorption of strontium (II), cobalt (11), zinc (11), and iron (III) on chitosan from sodium chloride solution have been reported (Nishimura et al. 1995). Adsorption behavior of Cu (II) (Minamisawa et al. 1996, Wu et al. 2000) and cobalt (11) (Minamisawa et al. 1999) were investigated. The amount of cadmium removed by chitin increases with increase of these parameters at a specific time. The application to experimental results of the Langmuir and Freundlich models shows that the Langmuir model gives a better correlation coefficient. 

In [75,76], a method of decomposition of polyurethane rigid foams is described, using EG, DEG, and polyoxypropylenated pentaerythritol (with a hydroxyl number of 170 mg KOH/g) mixed with ethanolamines (mono-, di- and triethanolamine). Various salts of metals, such as tin, iron, sodium, potassium, zinc, calcium, copper, and cobalt were used as catalysts. The process products can be used as raw materials for the production of polyurethane plastics. 

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