Aiming to develop soluble and colorless polyimides, two novel diamines, 2,5-bis(2-trifluoromethyl-4-aminophenoxy)-1,4:3,6-dianhydrosorbitol (2a) and 2,5-bis(2-methyl-4amino-phenoxy)-1,4:3,6-dianhydrosorbitol (2b), were designed and synthesized by the reduction of corresponding dinitro monomer which was obtained via solvent-free melt heating method. Polyimides (PI-(1-5)) containing 1,4:3,6-dianhydro-Dglucidol fragments were prepared from 2a and five kinds of common dianhydrides and PI-6 was synthesized from 2b and 4,4 0 -(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) via a two-step thermal imidization. All the polyimides were readily soluble in common polar solvents and could afford flexible, tough, and transparent films with transparency as high as 87% at 450 nm. Meanwhile, PI-(1-6) exhibited unexpectedly low dielectric constants of 2.02-2.52 at 1 MHz. In addition, analogs PI-7 derived from 2,5-bis(4-amino-phenoxy)-1,4:3,6-dianhydrosorbitol (2c) and 6FDA and PI-8 derived from 4,4 0 -bis(4-amino-2-trifluoromethylphenoxy)biphenyl (2d) and 6FDA were also obtained via a two-step thermal imidization for comparision with PI-(1-6) on aspects of thermal, mechnical, optical, electrical, and morphological properties. The structure-property relationships of PI-(1-8) were discussed in detail.

A strategy has been devised for improving the quality of polyelectrolyte multilayers formed via the layer-by-layer technique. This strategy involves host−guest complexation of the pendant ions of a polyelectrolyte to reduce their affinity toward the pendant ions of a complementary polyelectrolyte. Evidence for the effectiveness of this approach has been obtained on the basis of film thickness, permeability, and surface roughness measurements of polyelectrolyte multilayers derived from poly(sodium 4-styrenesulfonate) and poly(diallyldimethyammonium chloride), using β-cyclodextrin as a host molecule.

A novel aptamer-mediated fluorescence “turn off–on” nanosensor for highly sensitive and selective detection of kanamycin using CuInS2quantum dots@graphene oxide.

In order to obtain highly optical transparency polyimides, two novel aromatic diamine monomers containing pyridine and kinky structures, 1,1-bis[4-(5-amino-2-pyridinoxy)phenyl]diphenylmethane (BAPDBP) and 1,1-bis[4-(5-amino-2-pyridinoxy)phenyl]-1-phenylethane (BAPDAP), were designed and synthesized. Polyimides based on BAPDBP, BAPDAP, 2,2-bis[4-(5-amino-2-pyridinoxy)phenyl]propane (BAPDP) with various commercial dianhydrides were prepared for comparison and structure-property relationships study. The structures of the polyimides were characterized by Fourier transform infrared (FT-IR) spectrometer, wide-angle X-ray diffractograms (XRD) and elemental analysis. Film properties including solubility, optical transparency, water uptake, thermal and mechanical properties were also evaluated. The introduction of pyridine and kinky structure into the backbones that polyimides presented good optical properties with 91–97% transparent at 500 nm and a low cut-off wavelength at 353–398 nm. Moreover, phenyl pendant groups of the polyimides showed high glass transition temperatures (T g) in the range of 257–281 °C. These results suggest that the incorporating pyridine, kinky and bulky substituents to polymer backbone can improve the optical transparency effectively without sacrificing the thermal properties.