The practical deployment of polyester-based solid electrolytes such as poly(ε-caprolactone)(PCL)is hindered by two inherent material-level constraints:the semicrystalline nature of PCL chains severely restricts segme...The practical deployment of polyester-based solid electrolytes such as poly(ε-caprolactone)(PCL)is hindered by two inherent material-level constraints:the semicrystalline nature of PCL chains severely restricts segmental mobility and limits ionic conductivity,whereas interfacial instability against lithium metal anodes jeopardizes long-term cycling.Based on orthogonal polymerization technology combined with electrolyte structural design concepts,this work achieved a one-step fabrication of a polyester-based block copolymer electrolyte(BCPE)system comprising fluorinated segments(PTFEA)and poly(ε-caprolactone)(PCL).Structurally,this design enables a dual breakthrough in electrochemical performance:on one hand,the introduction of fluorinated segments with steric hindrance effects can effectively disrupt the regular arrangement of the PCL main chain,reduce the crystallinity of PCL within the polymer electrolyte,and significantly enhance the segmental mobility of the polymer matrix;on the other hand,during the charge/discharge cycles of lithium batteries,fluorinated segments can induce the formation of a LiF-rich solid electrolyte interphase(SEI)through in situ decomposition reactions,achieving interface stabilization and homogeneous lithiumion deposition regulation.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
Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methac...Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methacrylate was carried out in the presence of a polyfunctional chain transfer agent,pentaerythritol tetrakis(3-mercaptopropinate).At appropriate monomer conversions,two-arm PMMA having two residual thiol groups at the chain center or three-arm PMMA having one residual thiol group at the core were o...展开更多
Although intelligent hydrogels have shown bright potential application in biomedical fields,they were prepared by conventional methods and still face many serious challenges,such as uncontrollable stimulus-response an...Although intelligent hydrogels have shown bright potential application in biomedical fields,they were prepared by conventional methods and still face many serious challenges,such as uncontrollable stimulus-response and low response sensitivity.Recently,RAFT polymerization provides a versatile strategy for the fabrication of intelligent hydrogels with improved stimulus-response properties,owing to the ability to efficiently construct hydrogel precursors with well-defined structure,such as block copolymer,graft copolymer,star copolymer.In this review,we summarized the recent progress on intelligent hydrogels based on RAFT polymerization with emphasis on their fabrication strategies and applications for controlled drug delivery.展开更多
Controlled and homogeneous flee-radical polymerization of acrylamide （AM） in aqueous phase was realized by using S,S＇-bis（α, α＇-dimethyl-α＂-acetic acid）-trithiocarbonate as a reversible addition-fragmentatio...Controlled and homogeneous flee-radical polymerization of acrylamide （AM） in aqueous phase was realized by using S,S＇-bis（α, α＇-dimethyl-α＂-acetic acid）-trithiocarbonate as a reversible addition-fragmentation transfer （RAFT） agent. Linear increases in molecular weight with conversion and narrow molecular weight distribution were observed for polyacrylamide （PAM） throughout the polymerization. By this method, PAMs with controlled molecular weight （up to 1.0 ~ 106） and narrow molecular weight distribution （Mw/Mn 〈 1.2） were prepared. This study provides an effective method for synthesis of PAMs with narrow molecular weight distribution under environmentally friendly conditions.展开更多
A new A-B-A type of block copolymers,polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile（PAN-b-PDMSb-PAN）,which comprises two polymer blocks of different polarities and compatibilities,were synthesi...A new A-B-A type of block copolymers,polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile（PAN-b-PDMSb-PAN）,which comprises two polymer blocks of different polarities and compatibilities,were synthesized for the first time via reversible addition-fragmentation chain transfer polymerization.Reaction kinetics was investigated.PAN-b-PDMS-b-PAN films were prepared by spin-coating on glass chips.Significant order on the film surface morphologies was observed.展开更多
Photoenzymatic reversible addition-fragmenatation chain transfer(RAFT)emulsion polymerization,surfactant-free or ab initio,of various monomers is reported with oxygen toleranee.In surfactant-free emulsion polymerizato...Photoenzymatic reversible addition-fragmenatation chain transfer(RAFT)emulsion polymerization,surfactant-free or ab initio,of various monomers is reported with oxygen toleranee.In surfactant-free emulsion polymerizatoin,poly(N,N-dimethylacrylamide)s were used as stabilizer blocks for emulsion polymerization of methyl acrylate,n-butyl acrylate and styrene,producing well-defined amphiphilic block copolymers,including those with an ultrahigh molecular weight,at quantitative conversions.The controlled character of surfactant-free emulsion polymerization was confirmed by kinetic studies,chain extension studies and GPC analyses.Temporal control was demonstrated by light ON/OFF experiments.In ab initio emulsion polymerization of methyl acrylate and methyl methacrylate,low-dispersity hydrophobic polymers were synthesized with predictable molecular weights.This study extends the monomer scope suitable for photoenzymatic RAFT polymerization from hydrophilic to hydrophobic monomers and demonstrates that oxygen-toleranee can be equally achieved for emulsion polymerization with excellent RAFT control.展开更多
Stimulus-responsive vesicles have broad applications in a variety of areas. Herein, oxidation-responsive framboidal triblock copolymer vesicles are prepared by photoinitiated RAFT seeded emulsion polymerization of a t...Stimulus-responsive vesicles have broad applications in a variety of areas. Herein, oxidation-responsive framboidal triblock copolymer vesicles are prepared by photoinitiated RAFT seeded emulsion polymerization of a thioether-functionalized monomer using diblock copolymer vesicles as seeds. The obtained framboidal vesicles can transform into worms or spheres in the presence of reactive oxygen species,which can be further used for controlled release of cargos(e.g., silica nanoparticles).展开更多
Reversible addition-fragmentation transfer （RAPT） miniemulsion polymerizations for PMMA with cumyl dithiobenzoate （CDB） as a chain transfer agent （CTA） has been carried out. Higher temperature made the polymeriz...Reversible addition-fragmentation transfer （RAPT） miniemulsion polymerizations for PMMA with cumyl dithiobenzoate （CDB） as a chain transfer agent （CTA） has been carried out. Higher temperature made the polymerization much faster and the PDI remained below 1.20, when the temperature was upon 70 ℃.展开更多
The doubly thermo-responsive triblock copolymer nanoparticles of polystyrene-block-poly（N- isopropylacrylamide）-block-poly[N,N-（dimethylamino） ethyl methacrylate] （PS-b-PNIPAM-b-PDMAEMA） are successfully prepare...The doubly thermo-responsive triblock copolymer nanoparticles of polystyrene-block-poly（N- isopropylacrylamide）-block-poly[N,N-（dimethylamino） ethyl methacrylate] （PS-b-PNIPAM-b-PDMAEMA） are successfully prepared through the seeded RAFT polymerization in situ by using the PS-b-PNIPAM-TTC diblock copolymer nanoparticles as the seed. The seeded RAFT polymerization undergoes a pseudo-first-order kinetics procedure, and the molecular weight increases with the monomer conversion linearly. The hydrodynamic diameter （Dh） of the triblock copolymer nanoparticles increases with the extension of the PDMAEMA block. In addition, the double thermo-response behavior of the PS-b-PNIPAM-b-PDMAEMA nanoparticles is detected by turbidity analysis, temperature-dependent 1H-NMR analysis, and DLS analysis. The seeded RAFT polymerization is believed as a valid method to prepare triblock copolymer nanoparticles containing two thermo-responsive blocks.展开更多
Core-shell colloidal particles with a polymer layer have broad applications in different areas.Herein,we developed a two-step method combining aqueous surface-initiated photoinduced polymerization-induced self-assembl...Core-shell colloidal particles with a polymer layer have broad applications in different areas.Herein,we developed a two-step method combining aqueous surface-initiated photoinduced polymerization-induced self-assembly and photoinduced seeded reversible addition-fragmentation chain transfer(RAFT)polymerization to prepare a diverse set of core-shell colloidal particles with a well-defined polymer layer.Chemical compositions,structures,and thicknesses of polymer layers could be conveniently regulated by using different types of monomers and feed[monomer]/[chain transfer agent]ratios during seeded RAFT polymerization.展开更多
The novel cyclic trithiocarbonate was synthesized by dialkylation of trithiocarbonate anion with 2,2＇- bis（bromomethyl）biphenyl in a two-phase system using an onium salt as a phase-transfer agent. Styrene polymeriz...The novel cyclic trithiocarbonate was synthesized by dialkylation of trithiocarbonate anion with 2,2＇- bis（bromomethyl）biphenyl in a two-phase system using an onium salt as a phase-transfer agent. Styrene polymerization was carried out in the presence of cyclic trithiocarbonate （CTTC）. CTTC undergoes ring opening-polymerization and the incorporated trithiocarbonate moiety derived from CTTC performs as the reversible addition-fragmentation chain transfer （RAFT） agent. Through this mechanism, multiblock polys-tyrenes containing various narrow polydispersity blocks can be prepared.展开更多
The gradient copolymers of acrylic acid and trifluoroethyl methacrylate（coded as P（TFEMAgrad-AA）） were synthesized via reversible addition-fragmentation transfer（RAFT） emulsifier-free emulsion polymerization. Th...The gradient copolymers of acrylic acid and trifluoroethyl methacrylate（coded as P（TFEMAgrad-AA）） were synthesized via reversible addition-fragmentation transfer（RAFT） emulsifier-free emulsion polymerization. The spontaneous batch feeding approach was used to control the gradient chain sequence. Transmission electron microscopy（TEM） analysis revealed that the P（TFEMA-grad-AA） can self-assemble to form spherical micelles, rodlike micelles or vesicles in selective solvents. Morphological transition of the P（TFEMA-grad-AA） micelles was sensitive to the water content of the dioxane/water mixed solvent. More interestingly, Ag nanoparticles（NPs） were encapsulated by the P（TFEMA-grad-AA） micelles during the selfassembly process. The gradient chain sequence made the Ag NPs easily enter the core of the micelles, even when P（TFEMA-grad-AA） had less hydrophobic fluoro-units and more hydrophilic units. TEM images with energy dispersive spectrometer indicated that the nanocomposite micelles consisted of a Ag NPs core and a gradient copolymer shell.展开更多
The monomer 6-O-vinyladipoyl-D-glucopyranose( VAG)was synthesized by lipase catalyzed trans-esterification of divinyladipate with D-glucopyranose. A novel double hydrophilic glycopolymer poly( diethyleneglycol methacr...The monomer 6-O-vinyladipoyl-D-glucopyranose( VAG)was synthesized by lipase catalyzed trans-esterification of divinyladipate with D-glucopyranose. A novel double hydrophilic glycopolymer poly( diethyleneglycol methacrylate-co-6-Ovinyladipoyl-D-glucopyranose)( P( DEGMA-co-VAG)) with narrow polydispersity( PDI) and thermosensitivity was prepared by reversible addition-fragmentation chain transfer( RAFT)polymerization. P( DEGMA-co-VAG) was characterized by1 H NMR,FTIR and gel permeation chromatography( GPC). The characterization of UV-visible spectroscopy showed that the micelles from glycopolymer P( DEGMA-co-VAG) were thermo-responsive and the low critical solution temperature( LCST) could be controlled by the molar ratio of monomers. When the molar ratio of DEGMA and VAG was 2∶ 1,the LCST of P( DEGMA-co-VAG) was36 ℃ in aqueous solution,which could form nano micelles in the human body environment. It was found that P( DEGMA-co-VAG)was non-toxic at 0. 1-1 mg / m L concentrations when incubated with pig iliac endothelial cells( PIECs) for 24 h. Thus,the synthesized glycopolymers has great potential as drug delivery carriers.展开更多
The alternating copolymerization of hydroxyalkyl vinyl ethers and dialkyl maleates is investigated by conventional radical polymerization and reversible addition-fragmentation chain transfer polymerization(RAFT).The i...The alternating copolymerization of hydroxyalkyl vinyl ethers and dialkyl maleates is investigated by conventional radical polymerization and reversible addition-fragmentation chain transfer polymerization(RAFT).The influence of comonomer structure,comonomer feeding ratios,and monomer concentrations on the copolymerization and the copolymer structure have been investigated systematically.With 2-hydroxyethyl vinyl ether(HEVE)and dimethyl maleates(DMM)as comonomers,a well-defined alternating copolymer is prepared with M_(n)=3400 and M_(w)/M_(n)=1.93 up to 71.6% monomer.The alternating sequential chain structure of the copolymers has been proved by both NMR and matrixassisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS).The experimental reactivity ratios and theoretical calculated highest occupied molecular orbital and the lowest unoccupied molecular orbital of vinyl ethers and alkyl maleates support that these monomer pairs have tendency to form alternating copolymers.With 2-cyanopropan-2-yl N-methyl-N-(pyridin-4-yl)carbamodithioate as the RAFT agent,the molecular weight of HEVE and DMM copolymer increases with the monomer conversion,demonstrating a controlled radical polymerization feature with well-controlled molecular weight and relatively narrower molecular weight distribution.With alternating copolymer of HEVE and DMM as macro-CTA(M_(n)=5200 and M_(w)/M_(n)=1.46),both the chain extension with HEVE and DMM(M_(n)=10400 and M_(w)/M_(n)=1.72)and block copolymerization with vinyl acetate have been successfully achieved(M_(n)=8500 and M_(w)/M_(n)=1.52).展开更多
The tacticity of vinyl polymers is a key factor affecting the properties of materials.Recently,organic Brønsted acids have been demonstrated as effective catalysts for the development of highly stereoselective ca...The tacticity of vinyl polymers is a key factor affecting the properties of materials.Recently,organic Brønsted acids have been demonstrated as effective catalysts for the development of highly stereoselective cationic reversible addition-fragmentation chain transfer(RAFT)polymerizations of vinyl ethers,in which the use of RAFT agents could allow the control the molecular weight and tacticity of polymer products simultaneously.However,the effect of RAFT agents on the tacticity-regulation remains elusive and lacks of investigation.In this study,we synthesized four types of RAFT agents and evaluated their influence in the stereoselective cationic polymerization of isobutyl vinyl ether in the presence of PADI as a Brønsted acid catalyst,which unveils that the Z group of RAFT agents could not only affect the polydispersity of the products,but also exert a profound effect on the stereoselectivity.After extensive screening of the RAFT agents,high stereoregularity(isotacticity,90%m)was obtained when using dithiocarbonate ester-type RAFT agents with a benzyloxy Z group.展开更多
Transforming immature DCs into mature state to activate cellular immunity is a critical step in initiating immunoprophylaxis and immunotherapy.Lipopolysaccharides(LPS)can promote DCs maturation by binding receptor on ...Transforming immature DCs into mature state to activate cellular immunity is a critical step in initiating immunoprophylaxis and immunotherapy.Lipopolysaccharides(LPS)can promote DCs maturation by binding receptor on DCs surface,but their clinical application is limited due to biological toxicity.Although many LPS analogues have been developed,complex synthesis and purification hinder their practical application.Here,we propose a novel and simple strategy to synthesize LPS analogues with adjustable structural units.Using monomer units similar to the key functional groups of LPS,we synthesize LPS analogues with different group ratios by RAFT polymerization.The obtained analogues have little negative effect on cell viability.Compared with LPS,the analogues show greater promoting effect on DCs maturation.And the analogues can be applied to different scenarios since the degrees of promoting DCs maturation by LPS analogues with different group ratios are different.This strategy provides a new direction for synthesizing LPS analogues,and it has the potential to produce LPS analogues on a large scale with tunable promoting DCs maturation effect.展开更多
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
<div style="text-align:justify;"> A series of different sequence structure containing stearyl acrylate (SA) and hydroxyethyl acrylate (HEA) copolymer were synthesized via reversible addition-fragmentat...<div style="text-align:justify;"> A series of different sequence structure containing stearyl acrylate (SA) and hydroxyethyl acrylate (HEA) copolymer were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The crystallization property of PHEA-<em>b</em>-PSA, PHEA-<em>b</em>-PSA-<em>b</em>-PHEA, PSA-<em>b</em>-PHEA-<em>b</em>-PSA, PHEA-<em>co</em>-PSA, and PHEA-<em>grad-b</em>-PSA were characterized by Differential Scanning Calorimetry (DSC). The condensed structure of different sequence copolymers were investigated using small-angle X-ray scattering (SAXS). A series of copolymers with different sequence structure were coated on the surface of polyester fabric, which can be found that PHEA-b-PSA-b-PHEA block copolymer has good water repellency. </div>展开更多
基金financially supported by the National Natural Science Foundation of China(No.52573079)the Innovation and Talent Recruitment Base of New Energy Chemistry and Device(No.B21003).
文摘The practical deployment of polyester-based solid electrolytes such as poly(ε-caprolactone)(PCL)is hindered by two inherent material-level constraints:the semicrystalline nature of PCL chains severely restricts segmental mobility and limits ionic conductivity,whereas interfacial instability against lithium metal anodes jeopardizes long-term cycling.Based on orthogonal polymerization technology combined with electrolyte structural design concepts,this work achieved a one-step fabrication of a polyester-based block copolymer electrolyte(BCPE)system comprising fluorinated segments(PTFEA)and poly(ε-caprolactone)(PCL).Structurally,this design enables a dual breakthrough in electrochemical performance:on one hand,the introduction of fluorinated segments with steric hindrance effects can effectively disrupt the regular arrangement of the PCL main chain,reduce the crystallinity of PCL within the polymer electrolyte,and significantly enhance the segmental mobility of the polymer matrix;on the other hand,during the charge/discharge cycles of lithium batteries,fluorinated segments can induce the formation of a LiF-rich solid electrolyte interphase(SEI)through in situ decomposition reactions,achieving interface stabilization and homogeneous lithiumion deposition regulation.
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Heteroarm star-shaped polymers were synthesized by conventional free radical polymerization in two steps by the use of polyfunctional chain transfer agent.In the first step,free radical polymerization of methyl methacrylate was carried out in the presence of a polyfunctional chain transfer agent,pentaerythritol tetrakis(3-mercaptopropinate).At appropriate monomer conversions,two-arm PMMA having two residual thiol groups at the chain center or three-arm PMMA having one residual thiol group at the core were o...
基金supported by National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2018ZX10301402)International Cooperation and Exchange of the National Natural Science Foundation of China (No. 51820105004)+2 种基金the Science and Technology Program of Guangzhou (No. 201707010094)Guangdong Innovative and Entrepreneurial Research Team Program (Nos. 2013S086 and 2016ZT06S029)the Science and Technology Planning Project of Shenzhen (No. JCYJ20170307141438157)
文摘Although intelligent hydrogels have shown bright potential application in biomedical fields,they were prepared by conventional methods and still face many serious challenges,such as uncontrollable stimulus-response and low response sensitivity.Recently,RAFT polymerization provides a versatile strategy for the fabrication of intelligent hydrogels with improved stimulus-response properties,owing to the ability to efficiently construct hydrogel precursors with well-defined structure,such as block copolymer,graft copolymer,star copolymer.In this review,we summarized the recent progress on intelligent hydrogels based on RAFT polymerization with emphasis on their fabrication strategies and applications for controlled drug delivery.
文摘Controlled and homogeneous flee-radical polymerization of acrylamide （AM） in aqueous phase was realized by using S,S＇-bis（α, α＇-dimethyl-α＂-acetic acid）-trithiocarbonate as a reversible addition-fragmentation transfer （RAFT） agent. Linear increases in molecular weight with conversion and narrow molecular weight distribution were observed for polyacrylamide （PAM） throughout the polymerization. By this method, PAMs with controlled molecular weight （up to 1.0 ~ 106） and narrow molecular weight distribution （Mw/Mn 〈 1.2） were prepared. This study provides an effective method for synthesis of PAMs with narrow molecular weight distribution under environmentally friendly conditions.
基金supported by the National Natural Science Foundation of China (No. 20874057)the Key Natural Science Foundation of Shandong Province of China (No. ZR2011BZ001)
文摘A new A-B-A type of block copolymers,polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile（PAN-b-PDMSb-PAN）,which comprises two polymer blocks of different polarities and compatibilities,were synthesized for the first time via reversible addition-fragmentation chain transfer polymerization.Reaction kinetics was investigated.PAN-b-PDMS-b-PAN films were prepared by spin-coating on glass chips.Significant order on the film surface morphologies was observed.
基金We are thankful for financial support from the National Natural Science Foundation of China(No.21871175)the Fundamental Research Funds for the Central Universities.
文摘Photoenzymatic reversible addition-fragmenatation chain transfer(RAFT)emulsion polymerization,surfactant-free or ab initio,of various monomers is reported with oxygen toleranee.In surfactant-free emulsion polymerizatoin,poly(N,N-dimethylacrylamide)s were used as stabilizer blocks for emulsion polymerization of methyl acrylate,n-butyl acrylate and styrene,producing well-defined amphiphilic block copolymers,including those with an ultrahigh molecular weight,at quantitative conversions.The controlled character of surfactant-free emulsion polymerization was confirmed by kinetic studies,chain extension studies and GPC analyses.Temporal control was demonstrated by light ON/OFF experiments.In ab initio emulsion polymerization of methyl acrylate and methyl methacrylate,low-dispersity hydrophobic polymers were synthesized with predictable molecular weights.This study extends the monomer scope suitable for photoenzymatic RAFT polymerization from hydrophilic to hydrophobic monomers and demonstrates that oxygen-toleranee can be equally achieved for emulsion polymerization with excellent RAFT control.
基金support from the Science and Technology Program of Guangzhou(No.202102020631)the National Natural Science Foundation of China(Nos.22171055 and 21971047)+1 种基金Innovation Project of Education Department in Guangdong(No.2018KTSCX053)support from Guangdong Special Support Program(No.2017TX04N371)。
文摘Stimulus-responsive vesicles have broad applications in a variety of areas. Herein, oxidation-responsive framboidal triblock copolymer vesicles are prepared by photoinitiated RAFT seeded emulsion polymerization of a thioether-functionalized monomer using diblock copolymer vesicles as seeds. The obtained framboidal vesicles can transform into worms or spheres in the presence of reactive oxygen species,which can be further used for controlled release of cargos(e.g., silica nanoparticles).
文摘Reversible addition-fragmentation transfer （RAPT） miniemulsion polymerizations for PMMA with cumyl dithiobenzoate （CDB） as a chain transfer agent （CTA） has been carried out. Higher temperature made the polymerization much faster and the PDI remained below 1.20, when the temperature was upon 70 ℃.
基金financially supported by 973 Program of China,under the contract(No.2015CB655105)the National Science Fund for Distinguished Young Scholars(No.51225801)+1 种基金the National Natural Science Foundation of China(No.51408275)the Provincial Science and Technology Cooperation Project of Jiangsu-Guangxi cooperation project(No.BM2014050)
文摘The doubly thermo-responsive triblock copolymer nanoparticles of polystyrene-block-poly（N- isopropylacrylamide）-block-poly[N,N-（dimethylamino） ethyl methacrylate] （PS-b-PNIPAM-b-PDMAEMA） are successfully prepared through the seeded RAFT polymerization in situ by using the PS-b-PNIPAM-TTC diblock copolymer nanoparticles as the seed. The seeded RAFT polymerization undergoes a pseudo-first-order kinetics procedure, and the molecular weight increases with the monomer conversion linearly. The hydrodynamic diameter （Dh） of the triblock copolymer nanoparticles increases with the extension of the PDMAEMA block. In addition, the double thermo-response behavior of the PS-b-PNIPAM-b-PDMAEMA nanoparticles is detected by turbidity analysis, temperature-dependent 1H-NMR analysis, and DLS analysis. The seeded RAFT polymerization is believed as a valid method to prepare triblock copolymer nanoparticles containing two thermo-responsive blocks.
基金support from the Science and Technology Program of Guangzhou(No.2024A04J2821)the National Natural Science Foundation of China(Nos.52222301,22171055)the Guangdong Natural Science Foundation for Distinguished Young Scholar(No.2022B1515020078)。
文摘Core-shell colloidal particles with a polymer layer have broad applications in different areas.Herein,we developed a two-step method combining aqueous surface-initiated photoinduced polymerization-induced self-assembly and photoinduced seeded reversible addition-fragmentation chain transfer(RAFT)polymerization to prepare a diverse set of core-shell colloidal particles with a well-defined polymer layer.Chemical compositions,structures,and thicknesses of polymer layers could be conveniently regulated by using different types of monomers and feed[monomer]/[chain transfer agent]ratios during seeded RAFT polymerization.
基金This work was supported by the National Science Foundation of China (No. 20204013).
文摘The novel cyclic trithiocarbonate was synthesized by dialkylation of trithiocarbonate anion with 2,2＇- bis（bromomethyl）biphenyl in a two-phase system using an onium salt as a phase-transfer agent. Styrene polymerization was carried out in the presence of cyclic trithiocarbonate （CTTC）. CTTC undergoes ring opening-polymerization and the incorporated trithiocarbonate moiety derived from CTTC performs as the reversible addition-fragmentation chain transfer （RAFT） agent. Through this mechanism, multiblock polys-tyrenes containing various narrow polydispersity blocks can be prepared.
基金the National Natural Science Foundation of China(Nos.50803048 and 50703030)
文摘The gradient copolymers of acrylic acid and trifluoroethyl methacrylate（coded as P（TFEMAgrad-AA）） were synthesized via reversible addition-fragmentation transfer（RAFT） emulsifier-free emulsion polymerization. The spontaneous batch feeding approach was used to control the gradient chain sequence. Transmission electron microscopy（TEM） analysis revealed that the P（TFEMA-grad-AA） can self-assemble to form spherical micelles, rodlike micelles or vesicles in selective solvents. Morphological transition of the P（TFEMA-grad-AA） micelles was sensitive to the water content of the dioxane/water mixed solvent. More interestingly, Ag nanoparticles（NPs） were encapsulated by the P（TFEMA-grad-AA） micelles during the selfassembly process. The gradient chain sequence made the Ag NPs easily enter the core of the micelles, even when P（TFEMA-grad-AA） had less hydrophobic fluoro-units and more hydrophilic units. TEM images with energy dispersive spectrometer indicated that the nanocomposite micelles consisted of a Ag NPs core and a gradient copolymer shell.
基金National Natural Science Foundation of China(No.21303014)
文摘The monomer 6-O-vinyladipoyl-D-glucopyranose( VAG)was synthesized by lipase catalyzed trans-esterification of divinyladipate with D-glucopyranose. A novel double hydrophilic glycopolymer poly( diethyleneglycol methacrylate-co-6-Ovinyladipoyl-D-glucopyranose)( P( DEGMA-co-VAG)) with narrow polydispersity( PDI) and thermosensitivity was prepared by reversible addition-fragmentation chain transfer( RAFT)polymerization. P( DEGMA-co-VAG) was characterized by1 H NMR,FTIR and gel permeation chromatography( GPC). The characterization of UV-visible spectroscopy showed that the micelles from glycopolymer P( DEGMA-co-VAG) were thermo-responsive and the low critical solution temperature( LCST) could be controlled by the molar ratio of monomers. When the molar ratio of DEGMA and VAG was 2∶ 1,the LCST of P( DEGMA-co-VAG) was36 ℃ in aqueous solution,which could form nano micelles in the human body environment. It was found that P( DEGMA-co-VAG)was non-toxic at 0. 1-1 mg / m L concentrations when incubated with pig iliac endothelial cells( PIECs) for 24 h. Thus,the synthesized glycopolymers has great potential as drug delivery carriers.
基金financially supported by the National Natural Science Foundation of China(No.22171017).
文摘The alternating copolymerization of hydroxyalkyl vinyl ethers and dialkyl maleates is investigated by conventional radical polymerization and reversible addition-fragmentation chain transfer polymerization(RAFT).The influence of comonomer structure,comonomer feeding ratios,and monomer concentrations on the copolymerization and the copolymer structure have been investigated systematically.With 2-hydroxyethyl vinyl ether(HEVE)and dimethyl maleates(DMM)as comonomers,a well-defined alternating copolymer is prepared with M_(n)=3400 and M_(w)/M_(n)=1.93 up to 71.6% monomer.The alternating sequential chain structure of the copolymers has been proved by both NMR and matrixassisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS).The experimental reactivity ratios and theoretical calculated highest occupied molecular orbital and the lowest unoccupied molecular orbital of vinyl ethers and alkyl maleates support that these monomer pairs have tendency to form alternating copolymers.With 2-cyanopropan-2-yl N-methyl-N-(pyridin-4-yl)carbamodithioate as the RAFT agent,the molecular weight of HEVE and DMM copolymer increases with the monomer conversion,demonstrating a controlled radical polymerization feature with well-controlled molecular weight and relatively narrower molecular weight distribution.With alternating copolymer of HEVE and DMM as macro-CTA(M_(n)=5200 and M_(w)/M_(n)=1.46),both the chain extension with HEVE and DMM(M_(n)=10400 and M_(w)/M_(n)=1.72)and block copolymerization with vinyl acetate have been successfully achieved(M_(n)=8500 and M_(w)/M_(n)=1.52).
基金supported by the Recruitment Program of Global Experts of China,the National Natural Science Foundation of China(Nos.21602028 and 22371240)Beijing National Laboratory for Molecular Sciences(No.BNLMS201913)100-Talent program of Fujian,Fuzhou University and Xiamen University.
文摘The tacticity of vinyl polymers is a key factor affecting the properties of materials.Recently,organic Brønsted acids have been demonstrated as effective catalysts for the development of highly stereoselective cationic reversible addition-fragmentation chain transfer(RAFT)polymerizations of vinyl ethers,in which the use of RAFT agents could allow the control the molecular weight and tacticity of polymer products simultaneously.However,the effect of RAFT agents on the tacticity-regulation remains elusive and lacks of investigation.In this study,we synthesized four types of RAFT agents and evaluated their influence in the stereoselective cationic polymerization of isobutyl vinyl ether in the presence of PADI as a Brønsted acid catalyst,which unveils that the Z group of RAFT agents could not only affect the polydispersity of the products,but also exert a profound effect on the stereoselectivity.After extensive screening of the RAFT agents,high stereoregularity(isotacticity,90%m)was obtained when using dithiocarbonate ester-type RAFT agents with a benzyloxy Z group.
基金supported by the National Natural Science Foundation of China (Nos. 21935008 and 21774084)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)
文摘Transforming immature DCs into mature state to activate cellular immunity is a critical step in initiating immunoprophylaxis and immunotherapy.Lipopolysaccharides(LPS)can promote DCs maturation by binding receptor on DCs surface,but their clinical application is limited due to biological toxicity.Although many LPS analogues have been developed,complex synthesis and purification hinder their practical application.Here,we propose a novel and simple strategy to synthesize LPS analogues with adjustable structural units.Using monomer units similar to the key functional groups of LPS,we synthesize LPS analogues with different group ratios by RAFT polymerization.The obtained analogues have little negative effect on cell viability.Compared with LPS,the analogues show greater promoting effect on DCs maturation.And the analogues can be applied to different scenarios since the degrees of promoting DCs maturation by LPS analogues with different group ratios are different.This strategy provides a new direction for synthesizing LPS analogues,and it has the potential to produce LPS analogues on a large scale with tunable promoting DCs maturation effect.
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.
文摘<div style="text-align:justify;"> A series of different sequence structure containing stearyl acrylate (SA) and hydroxyethyl acrylate (HEA) copolymer were synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The crystallization property of PHEA-<em>b</em>-PSA, PHEA-<em>b</em>-PSA-<em>b</em>-PHEA, PSA-<em>b</em>-PHEA-<em>b</em>-PSA, PHEA-<em>co</em>-PSA, and PHEA-<em>grad-b</em>-PSA were characterized by Differential Scanning Calorimetry (DSC). The condensed structure of different sequence copolymers were investigated using small-angle X-ray scattering (SAXS). A series of copolymers with different sequence structure were coated on the surface of polyester fabric, which can be found that PHEA-b-PSA-b-PHEA block copolymer has good water repellency. </div>
