Abstract. The study of optically active polymers is a very active research field, and these materials have exhibited a number of interesting properties. Much of the attention in chiral polymers results from the potential of these materials for several specialized utilizations that are chiral matrices for asymmetric synthesis, chiral stationary phases for the separation of racemic mixtures, synthetic molecular receptors and chiral liquid crystals for ferroelectric and nonlinear optical applications. Recently, highly efficient methodologies and catalysts have been developed to synthesize various kinds of optically active compounds. Some of them can be applied to chiral polymer synthesis. In a few synthetic approaches for optically active polymers, chiral monomer polymerization has essential advantages in applicability of monomer, apart from both asymmetric polymerization of achiral or prochiral monomers and enantioselective polymerization of a racemic monomer mixture. The following are the up to date successful approaches to the chiral synthetic polymers by condensation polymerization reaction of chiral monomers.
Abstract. A new chiral poly(ester-imide) (PEI) was prepared via direct polyesterification of N,N!-(pyromellitoyl)-bis-(L-tyrosine dimethyl ester) and N-trimellitylimido-L-methionine using tosyl chloride/pyridine/N,N!-dimethylformamide system as a condensing agent. The resulting new chiral polymer was obtained in good yield and had good thermal stability as well as good solubility in common organic solvents. After that, PEI/titanium bionanocomposites (PEI/TiO 2 BNCs) were prepared using the modified nanosized TiO 2 via sonochemical reaction that can accelerate hydrolysis, increase collision chance for the reactive system and improve the dispersion of the nanoparticles in polymer matrix. The scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) results indicated that there is no aggregation of a large quantity of particles. Thermogravimetric analysis (TGA) confirmed that the heat stability of the BNC polymers in the temperature range of 400-800ºC was enhanced by addition of TiO 2 nanoparticles. Furthermore, in vitro toxicity test was employed for assessing the sensitivity of these compounds to microbial degradation. To this purpose, polymer and PEI/TiO 2 BNCs were investigated under soil burial conditions. The results of this study revealed that polymer and its BNCs are biologically active and non-toxic in the natural environment although some antimicrobial properties were found for BNCs.
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