Polyethers carboxylic acid terminated

The segmented polyamide elastomers are synthesized from MDI (4,4 -diisocyanato-diphenylmethane) and dicarboxylic acids and a carboxylic acid terminated aliphatic polyester, polycarbonate or polyether prepolymer with an average molecular weight of M = 500-5000. The dicarboxylic acids used as hard segment extenders are adipic and azelaic acid. Also, poly(ester amide) alloys are obtained using nylon-6,6 or polyesters (PEA/PBT). 

Another technique is to form the polyethers with terminal chloride groups." Hydroxy-group-terminated polyethers, for instance, can be converted to halogen-terminated polyethers. The products will react with ammonia and the amine-terminated polymer will react with carboxylic acid-terminated polyamides." ... 

In mimicking this type of function, noncyclic artificial carboxylic ionophores having two terminal groups of hydroxyl and carboxylic acid moieties were synthesized and the selective transport of alkali metal cations were examined by Yamazaki et al. 9 10). Noncyclic polyethers take on a pseudo-cyclic structure when coordinating cations and so it is possible to achieve the desired selectivity for specific cations by adjusting the length of the polyether chain 2). However, they were not able to observe any relationship between the selectivity and the structure of the host molecules in an active transport system using ionophores 1-3 10). (Table 1)... 

Ionophores, or polyether (PET) antibiotics, produced by various species of Streptomyces, possess broad spectrum anticoccidial activities. They are chemically characterized by several cyclic esters, a single terminal carboxylic acid group, and several hydroxyl groups. Representative members of this class include salinomycin (SAL), monensin (MON), lasalocid (LAS), narasin (NAR), maduramicin (MAD), and semduramicin (SEM). The main chemical properties of interest in the extraction methodology are their low polarities and instability under acidic conditions. They are able to form stable complexes with alkaline cations. All of these compounds, with the exception of LAS, bind monovalent cations (e.g., Na+ and K+). Lasalocid has a tendency to form dimers and can form complexes with divalent cations such as Mg2+ and Ca2+. The formation of metal complexes results in all of these compounds adopting a quasi-cyclic formation consequent to head-to-tail hydrogen bonding. No MRLs have yet been set by the EU for any of the carboxylic acid PETs (98). 

In 1995, a report of human illness with diarrhetic shellfish poisoning (DSP)-like symptoms in the Netherlands was eventually found to result from the consumption of poisoned mussels (Mytilus edulis) harvested from Killary Harbour, Ireland (McMahon 1996). Yasumoto, Satake, and co-workers eventually isolated and proposed a stracture for the causative agent of this condition azaspiracid-1 (la. Fig. 16.1). The unique polyether stracture of azaspiracid-1 (la) is characterized by several spiro-cyclic systems, including an azaspiro ring fused to a 2,9-dioxabicyclo[3.3.1]nonane system and a terminal carboxylic acid. In total, there are nine rings and twenty stereogenic centers within the structure proposed by Yasumoto and co-workers in 1998 (Satake 1998). This stracture was based primarily on NMR spectroscopic data and did not include absolute stereochemistry, nor did it specify relative stereochemistry between the ABCDE and FGHI domains. 

These membranes are characterized by their structure and function with resin formulation based on the poly-tetrafluoroethylene backbone with short polyether side-chains terminating in sulfonic acid or carboxylic acid groups. These functional groups can join through ionic cross-links forming ion-clusters. 

Acid anhydrides react first with the hydroxyl groups to form a monoester. The second carboxyl group of the anhydride is converted to the carboxylic acid, which preferably will react with a terminal epoxy group. The presence of hydroxyl groups in acidic conditions may lead to a polyether formation by the self-pol3merization of the epoxy group. ... 

Waterborne polyurethane resins are produced from maleinised monoglyceride (MMG) of sunflower oil, hydroxy-terminated polybutadiene, toluene diisocyanate and ethylene diamine. The carboxylic acid groups of MMG are neutralised by triethyl amine, making the resin water dispersible. The monoalkylated castor oil (MCO) or dehydrated castor oil (DCO) is treated with a polyether glycol at 120°C, followed by the addition of IPDI and DBTDL. To obtain a series of aqueous polyurethanes, butane diol and dimethylol propionic acids (DMPA) are added and the mixture heated to 70°C for two hours to produce a NCO-terminated pre-polymer which forms salt with triethylamine, giving a water-soluble polymer. The reaction mixture is dispersed in water and a chain extender, ethylene diamine, is added. Two aqueous polyurethanes, MCPU and DCPU, are finally obtained from MCO and DCO, respectively. 

Carboxylic functional polyols can be prepared by reacting hydroxyl terminated polyethers with unsaturated acids and a free radical initiator. Also carboxylic groups can be added to poly(ester/ethers) or other hydroxy terminated polymers by reacting with dianhydrides. 

In the first step of the synthesis, a conventional polyether- or polyester-based isocyanate-terminated prepolymer is obtained by condensation polymerization of a diol and a diol containing a carboxyl function, preferably reacting the hydroxyl groups of dimethylol propionic acid with isocyanate groups. In the next step, the carboxyl groups are neutralized with an amine which is subsequently dispersed in water and... 

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