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Polyols may be classified according to their chemistry. [5] Some of these chemistries are polyether, polyester, [6] polycarbonate [7] [8] and also acrylic polyols. [9] [10] Polyether polyols may be further subdivided and classified as polyethylene oxide or polyethylene glycol (PEG), polypropylene glycol (PPG) and Polytetrahydrofuran or PTMEG.
The main polycarbonate material is produced by the reaction of bisphenol A (BPA) and phosgene COCl 2. The overall reaction can be written as follows: The first step of the synthesis involves treatment of bisphenol A with sodium hydroxide, which deprotonates the hydroxyl groups of the bisphenol A. [6] (HOC 6 H 4) 2 CMe 2 + 2 NaOH → Na 2 (OC 6 ...
In 2016, Gnanou disclosed a method using a binary system associating triethyl borane with onium salts for efficient synthesis of polycarbonate polyols from CO2 and epoxides, highlighting high selectivity, productivity, and potential for cost-effective large-scale production. [11]
The use of polycarbonate based polyols in the synthesis can help overcome this weakness. [59] The wear and corrosion resistance is also not as good and hence they are often hybridized. [60] [61] Other strategies used to overcome some of the weaknesses include molecular design and mixing/compounding with inorganic rather than polymeric materials ...
The efficient direct synthesis of glycerol-1,2-carbonate from glycerol and inert CO 2 remains a major challenge. Direct synthesis ofn glycerol-1,2-carbonate Reports of yields of up to 35% in the reaction in methanol with dibutyltin oxide as a catalyst at 80 °C [ 21 ] could not be confirmed.
The nature of the polyol and the level of COOH groups and hydrophobic modification with other moieties can improve the hydrophilicity. Polyester polyols give the biggest improvements. [43] [44] Polycarbonate polyols also enhance properties, [45] [46] especially if the polycarbonate is also fluorinated. [47]
A polycarbonate is an oxocarbon dianion consisting of a chain of carbonate units, where successive carbonyl groups are directly linked to each other by shared additional oxygen atoms. That is, they are the conjugate bases of polycarbonic acids , the conceptual anhydrides of carbonic acid , or polymers of carbon dioxide .
Specialty polyols include polycarbonate polyols, polycaprolactone polyols, polybutadiene polyols, and polysulfide polyols. The materials are used in elastomer, sealant, and adhesive applications that require superior weatherability, and resistance to chemical and environmental attack.