This work confirms the new view of the initiation and propagation mechanism of the anionic polymerization previously proposed, based on the investigation of anionic bulk-polymerization of styrene and α-methyl styrene...This work confirms the new view of the initiation and propagation mechanism of the anionic polymerization previously proposed, based on the investigation of anionic bulk-polymerization of styrene and α-methyl styrene with the help of a self designed microflow device and characterized by GPC and in situ ^7Li NMR. It was found that n-BuLl tended to form the hexameric-aggregated structure and even to form the huge aggregated structure based on the former. These aggregations of initiators could directly initiate the anionic polymerization and form the su-pramolecule aggregations. The supramolecule aggregations inevitably blocked the diffusion of the monomers to the ion-pairs and resulted in a stationary-conversion platform. Then the aggregators were dissociated completely into equal binary-aggregated species, and the polymerization continued again rapidly before the termination. Tetrahy-drofuran （THF） acted as the electron donator, which could push the electron cloud to Li cation and make the aggre- gated ring of the active species rather loosened and facilitated the monomer to insert in. Therefore, a little THF can greatly promote the anionic polymerization. However, further addition of THF might block the channel between the ion-pairs and decrease the propagation rate. It was also found that the aggregated structure of the active species during the anionic polymerization only depends on the initiator aggregations which were formed before the polym-erization.展开更多
A novel series of polybenzazoles with rigid-rod benzoxazole cycle and soft methylene segment was designed and synthesized via solution condensation poly-merizations from 4,6-diamino-l,3-benzenediol dipho-sphate,tereph...A novel series of polybenzazoles with rigid-rod benzoxazole cycle and soft methylene segment was designed and synthesized via solution condensation poly-merizations from 4,6-diamino-l,3-benzenediol dipho-sphate,terephthalic acid and aliphatic dicarboxylic acid.The structures of polybenzazoles were characterized by means of FT-IR,1H NMR and Wide-angle X-ray diffrac-tion(WAXRD).All the polymers show excellent thermal stability and the TdS was above 471℃,The intrinsic vis-cosities[η]of the polymers ranged from 0.8 to 0.9.The UV-Vis absorption peaks of the polymers in MSA were blue-shifted from 429 nm for PBO to 291 nm for PBOC7,and the Stokes shifts in PL spectra enlarged.展开更多
基金Financial supports for this work from the Nature Science Foundation of China for the Major Program （No. 50933002）, the National High Technology Re-search and Development Program of China （863 Pro-gram, No. 2012AA040306） and Shanghai Leading Academic Discipline Project （No. B502） are gratefully acknowledged.
文摘This work confirms the new view of the initiation and propagation mechanism of the anionic polymerization previously proposed, based on the investigation of anionic bulk-polymerization of styrene and α-methyl styrene with the help of a self designed microflow device and characterized by GPC and in situ ^7Li NMR. It was found that n-BuLl tended to form the hexameric-aggregated structure and even to form the huge aggregated structure based on the former. These aggregations of initiators could directly initiate the anionic polymerization and form the su-pramolecule aggregations. The supramolecule aggregations inevitably blocked the diffusion of the monomers to the ion-pairs and resulted in a stationary-conversion platform. Then the aggregators were dissociated completely into equal binary-aggregated species, and the polymerization continued again rapidly before the termination. Tetrahy-drofuran （THF） acted as the electron donator, which could push the electron cloud to Li cation and make the aggre- gated ring of the active species rather loosened and facilitated the monomer to insert in. Therefore, a little THF can greatly promote the anionic polymerization. However, further addition of THF might block the channel between the ion-pairs and decrease the propagation rate. It was also found that the aggregated structure of the active species during the anionic polymerization only depends on the initiator aggregations which were formed before the polym-erization.
文摘A novel series of polybenzazoles with rigid-rod benzoxazole cycle and soft methylene segment was designed and synthesized via solution condensation poly-merizations from 4,6-diamino-l,3-benzenediol dipho-sphate,terephthalic acid and aliphatic dicarboxylic acid.The structures of polybenzazoles were characterized by means of FT-IR,1H NMR and Wide-angle X-ray diffrac-tion(WAXRD).All the polymers show excellent thermal stability and the TdS was above 471℃,The intrinsic vis-cosities[η]of the polymers ranged from 0.8 to 0.9.The UV-Vis absorption peaks of the polymers in MSA were blue-shifted from 429 nm for PBO to 291 nm for PBOC7,and the Stokes shifts in PL spectra enlarged.
