Pseudo poly carbonates

Introduction 207 12.5 Carbonate-Based "Pseudo" Poly(Amino Acids) 212... 

Synthesis of "Pseudo" Poly(Amino Acid) 208 12.5.1 Synthesis of Carbonate-Based "Pseudo" ... 

CARBONATE-BASED "PSEUDO" POLY(AMINO ACIDS)... 

Carbonates (ester of carbonic acid) are functional groups in which the carbon atom is surrounded by three oxygen atoms. This structure consists of two single and one double bonds. Carbonate-based pseudo poly(amino acids) are the first bioactive polymers to be synthesized and have been reported initially by Kohn [40,41]. The molecular weights of these polymers range from 120 to 450 kDa [40,41]. Their... 

TABLE 12.3 "Pseudo" Poly(amino acids) Formulated with Carbonates ... 

Sartor et studied the DSC curve of IPN of composition 25% PU/75% PMMA. In contrast to usual observations, the Tg increased over a very broad temperature range, which is due to the distribution of relaxation time. Chen et al. studied pseudo IPNs of linear poly(carbonate urethane) and crosslinked polychloroprene. The single-phase morphology of this pseudo-IPN has been confirmed by DSC measurements. 

FIGURE 5.13 Pseudo polyfamino acids). Poly(carbonate) (a) and poly(arylate) (b) desaminotyrosyl-tyrosine copolymers. The R group is usually an alkyl chain. 

The alkali-catalysed methanolysis of poly(2,2-bis(4-hydroxyphenyljpropane carbonate) (PC) in a mixture of methanol (MeOH) and toluene or dioxane was studied. The treatment of PC in meOH, with a catalytic amount of sodium hydroxide, yielded only 7% bisphenol A. Using a mixed solvent of MeOH and toluene completely depolymerised PC to give 96% free bisphenol A in solid form and dimethyl carbonate in solution. The eharaeteristies of the catalysis are discussed together with the pseudo-first rate kinetics of the depolymerisation. The reaetion eonditions were investigated to facilitate the reeyeling of PC plasties. 17 refs. 

Palladium-catalyzed cross-coupling is a powerful tool for the synthesis of various 7c-conjugated molecules and polymers through sp and sp carbon-carbon bond formation [17-20]. Scheme 3 shows the synthetic routes for poly (p-arylene-ethynylene)-type (PAE-type) jc-stacked polymers by Sonogashira-Hagihara cross-coupling [21, 22]. Polymer 13 was obtained from the monomers pseudo-para-dibromo[2.2]... 

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