摘要
The effects of the chain length, active end group and concentration on the association of living polystyryllithium (PS(-)Li(+)) chains in benzene were examined by a combination of static and dynamic laser light scattering in a cuvette equipped with a high-vacuum stopcock. The results show that long PS(-)Li(+) chains (M(w) > 1 x 10(4)) usually form dimers in the solution. In contrast, shorter PS(-)Li(+) chains exhibit two relaxation modes, where the fast mode is related to the translational diffusion of the living chain dimers. The end capping of the living chain with bulky 1,1-diphenylethene (DPE) leads to an intensity increase of the slow mode, indicating that the slow mode is not due to the chain aggregates but to temporal aggregates or long-range density fluctuation induced by weak electrostatic dipole-dipole interaction between ionic pairs at the chain ends.
The effects of the chain length, active end group and concentration on the association of living polystyryllithium (PS(-)Li(+)) chains in benzene were examined by a combination of static and dynamic laser light scattering in a cuvette equipped with a high-vacuum stopcock. The results show that long PS(-)Li(+) chains (M(w) > 1 x 10(4)) usually form dimers in the solution. In contrast, shorter PS(-)Li(+) chains exhibit two relaxation modes, where the fast mode is related to the translational diffusion of the living chain dimers. The end capping of the living chain with bulky 1,1-diphenylethene (DPE) leads to an intensity increase of the slow mode, indicating that the slow mode is not due to the chain aggregates but to temporal aggregates or long-range density fluctuation induced by weak electrostatic dipole-dipole interaction between ionic pairs at the chain ends.
基金
supported by the Hong Kong Special Administration Region Earmarked Grants(CUHK4036/05P,2160269)
the Chinese Academy of Sciences Special Grant(No.KJCX2-SW-H14)
China Postdoctoral Science Foundation(No.20070420727)
the National Natural Science Foundation Project(No.20574065).
