A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block...A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A. Transmission electron microscopy （TEM）, small angle X-rays and neutron scattering （SAXS and SANS） were used to study their morphologies. After annealing the samples over weeks at a temperature within the nematic temperature range of block B, different morphologies （disordered, lamellar, perforated layer and hexagonal cylinder） were observed by TEM. The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application, as well as the phase period and the order-disorder transition （ODT） were studied in situ by SANS.展开更多
The structures and energies of the side-on complexes B2（N2）2 and monocyclic Bn（N2）nm （n = 3～6,m = -1～＋2） between N2 （1∑＋g） and B （2P） have been investigated by the DFT-B3LYP and MP2 methods at the 6-311...The structures and energies of the side-on complexes B2（N2）2 and monocyclic Bn（N2）nm （n = 3～6,m = -1～＋2） between N2 （1∑＋g） and B （2P） have been investigated by the DFT-B3LYP and MP2 methods at the 6-311＋G（2d） and aug-cc-pVTZ levels. The analyses of NICS （Nucleus Independent Chemical Shifts）,NBO （nature bond orbital）,AIM （atoms in molecules） and frontal orbitals have been used to reveal the origin of coordination bond between the π-electron donor N2 group and B atom,accompanied by the comparison with the end-on complexes. The results have indicated that the side-on coordination complexes can be formed due to the relative strong fluidity of the π-electrons,and the nature of the coordination bond has been exposed to be that the N2 group offers 1πu electron to the 2p orbital of boron. The coordinate energies of the side-on complexes are less than those of the end-on complexes. Furthermore,the aromaticity of side-on coordination complex is weaker than that of the corresponding end-on coordination complex.展开更多
基金financially supported by the French Embassy in China(Beijing) to Wei Deng(Bourse doctorale en altemance 2004-2007)
文摘A series of azobenzene containing side-on liquid crystalline ABA triblock copolymers were investigated. This triblock series possesses the same central liquid crystal block B and various lengths of the amorphous block A. Transmission electron microscopy （TEM）, small angle X-rays and neutron scattering （SAXS and SANS） were used to study their morphologies. After annealing the samples over weeks at a temperature within the nematic temperature range of block B, different morphologies （disordered, lamellar, perforated layer and hexagonal cylinder） were observed by TEM. The alignment behavior of these azo triblock copolymers in the magnetic field for artificial muscle application, as well as the phase period and the order-disorder transition （ODT） were studied in situ by SANS.
文摘The structures and energies of the side-on complexes B2（N2）2 and monocyclic Bn（N2）nm （n = 3～6,m = -1～＋2） between N2 （1∑＋g） and B （2P） have been investigated by the DFT-B3LYP and MP2 methods at the 6-311＋G（2d） and aug-cc-pVTZ levels. The analyses of NICS （Nucleus Independent Chemical Shifts）,NBO （nature bond orbital）,AIM （atoms in molecules） and frontal orbitals have been used to reveal the origin of coordination bond between the π-electron donor N2 group and B atom,accompanied by the comparison with the end-on complexes. The results have indicated that the side-on coordination complexes can be formed due to the relative strong fluidity of the π-electrons,and the nature of the coordination bond has been exposed to be that the N2 group offers 1πu electron to the 2p orbital of boron. The coordinate energies of the side-on complexes are less than those of the end-on complexes. Furthermore,the aromaticity of side-on coordination complex is weaker than that of the corresponding end-on coordination complex.
