Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl d...Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl dithiobenzoate (PEDB) under low ratio of RAFT agent to initiator. The kinetic model was developed to predict polymerization rate, which indicates that the RAFT polymerization of St is a first-order reaction. In the range of experimental conversions, the plots of -ln(1-x) against time t are approximately linear (x is monomer conversion). The kinetic study reveals the existence of strong rate retardation in RAFT polymerization of styrene. A coefficient K_r is defined to estimate the rate retardation in the RAFT system considering the assumption that the retardation in polymerization rate is mainly attributed to slow fragmentation of the intermediate radicals. K_r relates to the structure of RAFT agents as well as the concentrations of RAFT agent and azobis isobutyronitrile (AIBN). For a certain RAFT agent, the value of K_r is enhanced by the increase in the initial concentration of RAFT agent and the higher ratio of RAFT to AIBN. With the same recipe for different RAFT agents, the increasing trend for the values of K_r is BDB<PEDB<CDB.展开更多
Cyclic polymers have attracted more and more attentions in recent years because of their unique topological structures and characteristic properties in both solution and bulk state. There are relatively few reports on...Cyclic polymers have attracted more and more attentions in recent years because of their unique topological structures and characteristic properties in both solution and bulk state. There are relatively few reports on cyclic polymers, partly because of the more demanding synthetic procedures. In recent years, 'click' reaction, especially Cu(I)-catalyzed azide-alkyne cycloaddition(CuAAC), has been widely utilized in the synthesis of cyclic polymer materials because of its high efficiency and low susceptibility to side reactions. In this review, we will focus on three aspects:(1) Constructions of monocyclic polymer using CuAAC 'click' chemistry;(2) Formation of complex cyclic polymer topologies through CuAAC reactions;(3) Using CuAAC 'click' reaction in the precise synthesis of molecularly defined macrocycles. We believe that the CuAAC click reaction is playing an important role in the design and synthesis of functional cyclic polymers.展开更多
文摘Bulk polymerizations of styrene (St) were carried out in the presence of three reversible addition fragmentation chain transfer (RAFT) agents benzyl dithiobenzoate (BDB), cumyl dithiobenzoate(CDB), and 1-phenylethyl dithiobenzoate (PEDB) under low ratio of RAFT agent to initiator. The kinetic model was developed to predict polymerization rate, which indicates that the RAFT polymerization of St is a first-order reaction. In the range of experimental conversions, the plots of -ln(1-x) against time t are approximately linear (x is monomer conversion). The kinetic study reveals the existence of strong rate retardation in RAFT polymerization of styrene. A coefficient K_r is defined to estimate the rate retardation in the RAFT system considering the assumption that the retardation in polymerization rate is mainly attributed to slow fragmentation of the intermediate radicals. K_r relates to the structure of RAFT agents as well as the concentrations of RAFT agent and azobis isobutyronitrile (AIBN). For a certain RAFT agent, the value of K_r is enhanced by the increase in the initial concentration of RAFT agent and the higher ratio of RAFT to AIBN. With the same recipe for different RAFT agents, the increasing trend for the values of K_r is BDB<PEDB<CDB.
基金financially supported by the National Natural Science Foundation of China(No.21234005)the State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Program of Innovative Research Team of Soochow University
文摘Cyclic polymers have attracted more and more attentions in recent years because of their unique topological structures and characteristic properties in both solution and bulk state. There are relatively few reports on cyclic polymers, partly because of the more demanding synthetic procedures. In recent years, 'click' reaction, especially Cu(I)-catalyzed azide-alkyne cycloaddition(CuAAC), has been widely utilized in the synthesis of cyclic polymer materials because of its high efficiency and low susceptibility to side reactions. In this review, we will focus on three aspects:(1) Constructions of monocyclic polymer using CuAAC 'click' chemistry;(2) Formation of complex cyclic polymer topologies through CuAAC reactions;(3) Using CuAAC 'click' reaction in the precise synthesis of molecularly defined macrocycles. We believe that the CuAAC click reaction is playing an important role in the design and synthesis of functional cyclic polymers.
