光诱导电子转移可逆加成-断裂链转移聚合(Photoinduced Electron Transfer-Reversible Addition Fragmentation Chain Transfer Polymerization,PET-RAFT聚合,凭借能耗低、反应条件温和、时空可控、反应正交性和耐氧性等特性在聚合领域...光诱导电子转移可逆加成-断裂链转移聚合(Photoinduced Electron Transfer-Reversible Addition Fragmentation Chain Transfer Polymerization,PET-RAFT聚合,凭借能耗低、反应条件温和、时空可控、反应正交性和耐氧性等特性在聚合领域得到广泛关注与应用,在表面改性方面,PET-RAFT聚合被用于改善材料的表面特性,如生物相容性和抗黏附性。在生物医药领域,PET-RAFT聚合技术用于药物递送系统,如球形胶束和囊泡。此外,PET-RAFT聚合在3D打印和激光写入中的应用展示了其在精确控制材料结构和功能化方面的巨大潜力。PET-RAFT聚合的关键在于寻找合适的光催化剂,目前催化剂包括均相和非均相催化剂体系,均相催化体系如过渡金属络合物、卟啉及酞菁类催化剂、有机染料和半导体材料等,非均相催化剂体系如宏观材料负载型、纳米材料负载型、金属有机框架型、共价有机框架型和共轭微孔聚合物等,其中非均相催化剂可以通过离心和过滤分离对光催化剂进行有效回收利用。未来研究者将开发新型低成本、高效率、易回收、无毒的光催化剂以提高低能光子的使用效率和改善光聚合与环境的相容性。展开更多
Polymerization-induced self-assembly(PISA)has become one of the most versatile approaches for scalable preparation of linear block copolymer nanoparticles with various morphologies.However,the controlled introduction ...Polymerization-induced self-assembly(PISA)has become one of the most versatile approaches for scalable preparation of linear block copolymer nanoparticles with various morphologies.However,the controlled introduction of branching into the core-forming block and the effect on the morphologies of block copolymer nanoparticles under PISA conditions have rarely been explored.Herein,a series of multifunctional macromolecular chain transfer agents(macro-CTAs)were first synthesized by a two-step green light-activated photoiniferter polymerization using two types of chain transfer monomers(CTMs).These macro-CTAs were then used to mediate reversible addition-fragmentation chain transfer(RAFT)dispersion polymerization of styrene(St)to prepare block copolymers with different core-forming block structures and the assemblies.The effect of the core-forming block structure on the morphology of block copolymer nanoparticles was investigated in detail.Transmission electron microscopy(TEM)analysis indicated that the brush-like core-forming block structure facilitated the formation of higher-order morphologies,while the branched core-forming block structure favored the formation of lower-order morphologies.Moreover,it was found that using macroCTAs with a shorter length also promoted the formation of higher-order morphologies.Finally,structures of block copolymers and the assemblies were further controlled by changing the structure of macro-CTA or using a binary mixture of two different macro-CTAs.We expect that this work not only sheds light on the synthesis of block copolymer nanoparticles but also provide important mechanistic insights into PISA of nonlinear block copolymers.展开更多
在基于三副本策略的分布式存储系统中,当存储节点上的硬盘出现故障时,常见的处理方式是等待系统预设的时间.如果该故障硬盘超时未恢复,才开始恢复故障硬盘上的副本.这种处理方式存在的问题是,当三副本组中存在故障副本时,如果该副本组...在基于三副本策略的分布式存储系统中,当存储节点上的硬盘出现故障时,常见的处理方式是等待系统预设的时间.如果该故障硬盘超时未恢复,才开始恢复故障硬盘上的副本.这种处理方式存在的问题是,当三副本组中存在故障副本时,如果该副本组再有一个副本所在的硬盘发生故障,将导致系统无法继续提供服务,且不能自动恢复.本文提出一种基于日志副本的改进的Raft共识算法,即LR-Raft (log replica based Raft),日志副本没有完整状态机,可以快速加入集群,并参与投票与共识,提升了存在故障硬盘时系统的可用性;可以解决短时间内三副本中两个副本故障导致集群不可用和丢失数据的问题.实验结果表明,在副本组中引入日志副本后,与原Raft相比,LR-Raft在不同的工作负载下读写时延均明显降低,吞吐量显著提升.展开更多
文摘光诱导电子转移可逆加成-断裂链转移聚合(Photoinduced Electron Transfer-Reversible Addition Fragmentation Chain Transfer Polymerization,PET-RAFT聚合,凭借能耗低、反应条件温和、时空可控、反应正交性和耐氧性等特性在聚合领域得到广泛关注与应用,在表面改性方面,PET-RAFT聚合被用于改善材料的表面特性,如生物相容性和抗黏附性。在生物医药领域,PET-RAFT聚合技术用于药物递送系统,如球形胶束和囊泡。此外,PET-RAFT聚合在3D打印和激光写入中的应用展示了其在精确控制材料结构和功能化方面的巨大潜力。PET-RAFT聚合的关键在于寻找合适的光催化剂,目前催化剂包括均相和非均相催化剂体系,均相催化体系如过渡金属络合物、卟啉及酞菁类催化剂、有机染料和半导体材料等,非均相催化剂体系如宏观材料负载型、纳米材料负载型、金属有机框架型、共价有机框架型和共轭微孔聚合物等,其中非均相催化剂可以通过离心和过滤分离对光催化剂进行有效回收利用。未来研究者将开发新型低成本、高效率、易回收、无毒的光催化剂以提高低能光子的使用效率和改善光聚合与环境的相容性。
基金financially supported by the National Natural Science Foundation of China(Nos.22171055 and 52222301)the Guangdong Natural Science Foundation for Distinguished Young Scholar(No.2022B1515020078)the Science and Technology Program of Guangzhou(No.2024A04J2821)。
文摘Polymerization-induced self-assembly(PISA)has become one of the most versatile approaches for scalable preparation of linear block copolymer nanoparticles with various morphologies.However,the controlled introduction of branching into the core-forming block and the effect on the morphologies of block copolymer nanoparticles under PISA conditions have rarely been explored.Herein,a series of multifunctional macromolecular chain transfer agents(macro-CTAs)were first synthesized by a two-step green light-activated photoiniferter polymerization using two types of chain transfer monomers(CTMs).These macro-CTAs were then used to mediate reversible addition-fragmentation chain transfer(RAFT)dispersion polymerization of styrene(St)to prepare block copolymers with different core-forming block structures and the assemblies.The effect of the core-forming block structure on the morphology of block copolymer nanoparticles was investigated in detail.Transmission electron microscopy(TEM)analysis indicated that the brush-like core-forming block structure facilitated the formation of higher-order morphologies,while the branched core-forming block structure favored the formation of lower-order morphologies.Moreover,it was found that using macroCTAs with a shorter length also promoted the formation of higher-order morphologies.Finally,structures of block copolymers and the assemblies were further controlled by changing the structure of macro-CTA or using a binary mixture of two different macro-CTAs.We expect that this work not only sheds light on the synthesis of block copolymer nanoparticles but also provide important mechanistic insights into PISA of nonlinear block copolymers.
文摘在基于三副本策略的分布式存储系统中,当存储节点上的硬盘出现故障时,常见的处理方式是等待系统预设的时间.如果该故障硬盘超时未恢复,才开始恢复故障硬盘上的副本.这种处理方式存在的问题是,当三副本组中存在故障副本时,如果该副本组再有一个副本所在的硬盘发生故障,将导致系统无法继续提供服务,且不能自动恢复.本文提出一种基于日志副本的改进的Raft共识算法,即LR-Raft (log replica based Raft),日志副本没有完整状态机,可以快速加入集群,并参与投票与共识,提升了存在故障硬盘时系统的可用性;可以解决短时间内三副本中两个副本故障导致集群不可用和丢失数据的问题.实验结果表明,在副本组中引入日志副本后,与原Raft相比,LR-Raft在不同的工作负载下读写时延均明显降低,吞吐量显著提升.
