Synthesis and characterization of novel, optically active polyamides derived from S-valine natural amino acid and bulky anthracenic side chain

Preparation and Chiral Applications of Optically Active Polyamides

Chirality is omnipresent in nature and plays vital roles in living organism, and has become a hot research topic across multidisciplinary fields including chemistry, biology, physics, and material science. Meanwhile, polyamides constitute an important class of polymers and have received significant attention owing to their outstanding properties and wide-ranging applications in many areas. Judiciously introducing chirality into polyamides will undoubtedly obtain attractive chiral polymers, namely, optically active polyamides. This review describes the preparation methods of chiral polyamides, including solution polycondensation, interfacial polycondensation, ring-open polymerization, and others; the newly emerging categories of chiral polyamides, i.e., helical polyamides, chiral polyamide-imides, are also presented. The applications of optically active polyamides in chiral research fields including asymmetric catalysis, membrane separation, and enantioselective crystallization are also summarized. In addition, current challenges in chiral polyamides are further presented and future perspectives in the field are proposed.

Investigation on synthesis and morphology characteristic of novel chiral poly(amide-imide)/TiO2 nanocomposites derived from L-isoleucine-based diacid and 4,4'-methylenebis(3-chloro-2,6-diethylaniline)

In the present investigation, a new optically active poly(amide-imide) (PAI) was synthesized from the polymerization reaction of N-trimellitylimido-L-isoleucine diacid with 4,4'-methylenebis(3-chloro-2,6-diethylaniline) using molten tetra-n-butylammonium bromide and triphenyl phosphite as a condensing agent and green media. Then the surface of titanium dioxide (TiO2) nanoparticles was modified with γ-aminopropyltriethoxyl silane as a coupling agent. The obtained polymer and inorganic metal oxide nanoparticles were used to prepare of PAI/TiO2 nanocomposites (NCs) through ultrasonic irradiation. The formation of PAI was confirmed by 1H NMR, fourier transform IR spectroscopy (FT-IR), specific rotation and elemental analysis. The resulting polymer was synthesized with good yield and moderate inherent viscosities around 0.27 dL/g. The resulting NCs were also characterized by FT-IR, powder X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The TEM and FE-SEM results indicated that the nanoparticles were dispersed homogeneously in PAI matrix on nanoscale. TGA confirmed that the heat stability of the NCs was improved in the presence of TiO2 nanoparticles. Transmittance behavior of the obtained PAI/TiO2 NCs was investigated by UV-vis spectroscopy.