Dendritic aromatic polyesters

Dendritic polymers are used as functional thin layers. Highly branched aromatic polyesters with polar end groups show good response behaviour in gas phase and liquid sensors [46]. Ease of recycling of the expensive platinum complexes (e.g. by nanofiltration) is a positive aspect of the use of such sensor den-drimers [47]. 

Busson P, Ihre H, Hult A (1998) Synthesis of a novel dendritic liquid crystalline polymer showing a ferroelectric SmC phase. J Am Chem Soc 120 9070-9071 Calundarm GW (1980) Melt processable thermotropic wholly aromatic polyester. US Patents 4184996... 

Frechet and his co-workers then characterized their dendritic polyesters both in the solid state [14,19] and in solution [ 19] and compared their behavior with that exhibited by linear samples of the same chemical structure. The physical properties of their aromatic polyesters seemed not to be affected by the... 

The most frequently apphed technique for the separation of polymers, namely size-exclusion chromatography (SEC), is based on the well-balanced interactions between the column material, the solvent, and the polymer sample. In order to achieve a complete separation according to size, and also to determine reliable polydispersity values, enthalpic interactions between the sample and column material must be excluded, as only entropic interactions lead to SEC separation. This is not always possible in the case of dendritic polymers which, being multifunctional architectures, have interactions with the column material that are effectively predestined. It has been repeatedly observed that this problem is more severe for higher molar mass products. An example of aromatic hb polyesters with different... 

A one-pot solution polymerization was performed at room temperature using partially aromatic monomers, namely 4,4-bis(4 -hydroxyphenyl)valeric acid as AB2 and 3-(4-hydroxyphenyl)propionic acid as AB [118] (see Table 1, entry 5 for monomer combination), in the presence of 4-(A, A dimethylamino) pyridinium 4-tosylate (DPTS) as catalyst and dicyclohexylcarbodiimide (DCC). The dependencies of the DB and the thermal properties of the polymers on the AB AB2 monomer ratio were studied. Polyesters with statistical dendritic topology, controlled DB, and > 35,000 g/mol were obtained. The DB was found to decrease with an increase in the amount of AB monomers and increasing comonomer ratio in the polymer (rp = ratio of AB to AB2) as shown in Fig. 1. Interestingly, the DB for hb homopolyester and branched copolyester at rp = 0.46 was similar (see Fig. la), because of the fact that on adding the small-sized linear AB to the more voluminous AB2 monomers in the reaction mixture, the steric effects decreased, which promoted the formation of dendritic units formed by the AB2 monomer. The thermal... 

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