Polyethylene glycol copolyesters

Segmented copolyester as hydrophilic substrates based on end-grafted polyethylene glycol (PEG)... 

Gel-forming (GF) absorbable copolyesters made by end-grafting one or more cyclic monomer onto a polyalkylene glycol, such as polyethylene glycol for use in tissue repair and controlled delivery of bioactive agents... 

Interlinking hydroxy-terminated, low molecular weight polyesters with polyethylene glycol using dicarboxylic acid anhydride and a carbodiimide. Almost all of the solid PEG-based copolyesters were developed for use as carriers for the controlled release of bioachve agents. 

All polymers were obtained by means of high-temperature acceptor-free polycondensation of terephthaloyl-bis(n-oxybenzoylchloride) with bis-4-oxybenzoyl derivatives of corresponding polyethylene glycols in solutions of high-boiling dissolvent in current inert gas. Copolyesters with mesogenic groups, extended up to 5 phenylene cycles and up to 15-17 oxyethylene links, are able to form the structure of nematic type. 

Biodegradable copolyesters patented by BASF [62, 63] are prepared by the initial condensation of 1,4-BDO and adipic acid to afford polytetramethylene adipate. This polymer is reacted with dimethyl terephthalate, 1,4-BDO, pyromellitic dianhydride and polyethylene glycol (MW of 600), in the presence of a titanium catalyst. A sulfonate compound is optionally incorporated into the polymer. 

The effect of incorporating p-hydroxybenzoic acid (I) into the structures of various unsaturated polyesters synthesised from polyethylene terephthalate (PET) waste depolymerised by glycolysis at three different diethylene glycol (DEG) ratios with Mn acetate as transesterification catalyst, was studied. Copolyesters of PET modified using various I mole ratios showed excellent mechanical and chemical properties because of their liquid crystalline behaviour. The oligoesters obtained from the twelve modified unsaturated polyesters (MUP) were reacted with I and maleic anhydride, with variation of the I ratio with a view to determining the effect on mechanical... 

Although this paper is concerned primarily with polytetramethylene ether glycol as the polymeric component of the copolyester elastomer, other polyglycols can be used for example, polyethylene ether glycol and poly-1,2-propylene ether glycol. Various combinations of short-chain diols and dicarboxylates may be used also, as mentioned (4). 

Because the types of exposures vary greafly depending on the nature of the work environment, materials also vary greatly. Materials considered for faceshields include polycarbonate (PC), cellulosics, polyethylene terephthalate glycol (PETG) and a new-generation copolyester recently introduced to the market that offers a combination of characterishcs to meet the changing needs of the face protechon market. 

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