In this work, we present firstly a study based on the calculation of the local spin densities of radical cations, which is known as a good measure of reactivity for coupling reactions, to obtain a theoretical basis for the one-step formation of poly (3.6-carbazole) and derivatives. Then we detail a DFT theoretical study of the geometric and electronic properties of oligomers based on carbazole and other CONJUGATED monomers. These results will be compared with the experimental ones and with works realized by other authors

The highly oriented light-emitting films of polyfluorene-based CONJUGATED POLYMERS blended with ultrahigh molecular weight polyethylene (U-PE) are prepared by using a tensile deformation technique. The high dichroic ratios of blue light (58 in photoluminescence (PL)) from the poly (9,9-dioctylfluorene) (PFO)/U-PE blending film and of green light (36 in PL) from the poly(9,9-dioctylfluorene) containing one fluorenone unit (PFF)/PFO/U-PE blending film are obtained. In the PFO/U-PE blending film, the variation of the photophysical properties of the blending films with the drawing ratio is discussed in detail which suggests that the CONJUGATED polymer chains are forced to a highly dispersed and oriented condition in the oriented PE matrix. The green band (g-band) of the blending film containing PFF is also studied and found in such a highly oriented condition, and a set of new evidence was obtained demonstrating the keto-defect origin of g-band.

A sort of novel stimuli-responsive water-soluble polymer-biomolecule conjugate, casein-g-poly(N-isopropylacrylamide) (PNIPAAm), was synthesized by free radical graft copolymerization of N-isopropylacrylamide (NIPAAm) from casein. The graft polymerization was induced by a small amount of t-butyl hydroperoxide (TBHP) in water under general condition. Free radicals on the amino groups of casein and t-butoxy radicals were generated concurrently, which initiated the graft copolymerization and homopolymerization of NIPAAm, respectively. The graft coPOLYMERS and homopolymer of NIPAAm were isolated and the chemical structure of the graft copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The phase-transition behaviours of the graft coPOLYMERS in aqueous solutions were investigated by the turbidity measurements. Casein-g-PNIPAAm did not precipitate at around the isoelectric pH (IP) of casein at 25°C and the lowest transmittance was changed as the pH changed. These results suggest that the PNIPAAm offers a greater hindrance to the aggregation of casein at 25°C and the casein offers a hindrance to the aggregation of PNIPAAm at the temperature of lower critical solution temperature (LCST) and at the pH apart from the IP. In addition, casein almost has no effect on LCST. The graft copolymer is stimulisensitive with respect to both temperature and pH in aqueous solutions and the polymeric micelles with different structures can be obtained simply by changing the environmental conditions. It associates into core-shell micelles in aqueous solution with collapsed PNIPAAm as a core as well as inverse core-hair micelles with expanded casein as a core on changing temperature or pH, indicated by transmission electron microscopy (TEM). With the casein being a nature protein and the graft coPOLYMERS are metal ion-free therefore, they may have great potential for biomedical and biomaterial applications.

Theoretical study on the geometries and electronic properties of new CONJUGATED compound based on thiophene and oxadiazole was carried out. The theoretical ground-state geometry and electronic structure of the studied molecules were obtained by the DFT method at B3LYP level with 6-31G (d) basis set. The electronic properties were determined by ZINDO/s, CIS/6-31G (d) and TD//B3LYP/6-31G (d) calculations were performed on the B3LYP/6-31 (d) optimized geometries. The effects of the ring structure and the substituents on the geometries and electronic properties of these materials are discussed. The results of this study demonstrated how the electronic properties can be tuned by the backbone ring or side group and suggest these compounds as good candidates for opto-electronic applications.