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
Photoredox-mediated reversible-deactivation radical polymerization(RDRP)is an effective approach to synthesize polymers with defined composition and architecture.Current photoinduced RDRP primarily depends on outer-sp...Photoredox-mediated reversible-deactivation radical polymerization(RDRP)is an effective approach to synthesize polymers with defined composition and architecture.Current photoinduced RDRP primarily depends on outer-sphere electron transfer or homolysis mechanisms.Herein,we describe an example of iodine-mediated RDRP facilitated by photoinduced charge transfer complex(CTC)catalysis.The approach uses cheap and easily accessible N^(-)heterocyclic nitrenium salt(NHN^(+)...I^(-))as the photoactive CTC.Upon the irradiation of visible light,NHN^(+)...I^(-)undergoes single electron transfer to generate NHN·and I·radicals.The NHN·radical activates dormant Pn-I polymers via inner-sphere single electron transfer,leading to the propagating Pn·radical for chain growth and the I^(-)anion for recovering the CTC,and the I·radical deactivates the polymerization via coupling with Pn·.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
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
A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-...A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-PDMAEMA-grafted-Fe3O4 magnetic nanoparticles with amino and epoxy groups were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis, and scanning electron microscopy. Lipase from Burkholderia cepacia was successfully immobilized onto the magnetic nanoparticles by physical adsorption and covalent bonding. The immobilization capacity of the magnetic particles is 0.5 mg lipase per mg support, with an activity recovery of up to 43.1% under the optimum immobilization condition. Biochemical characterization shows that the immobilized lipase exhibits improved thermal stability, good tolerance to organic solvents with high lg P, and higher p H stability than the free lipase at p H 9.0. After six consecutive cycles, the residual activity of the immobilized lipase is still over55% of its initial activity.展开更多
In homogeneous media, N,N-Dimethylacrylamide (DMA) was grafted copolymerization to cellulose by a metal-catalyzed atom transfer radical polymerization (ATRP) process. First, cellulose was dissolved in DMAc/LiCl system...In homogeneous media, N,N-Dimethylacrylamide (DMA) was grafted copolymerization to cellulose by a metal-catalyzed atom transfer radical polymerization (ATRP) process. First, cellulose was dissolved in DMAc/LiCl system, and it reacted with 2-bromoisobutyloyl bromide (BiBBr) to produce macroinitiator (cell-BiB). Then DMA was polymerized to the cellulose backbone in a homogeneous DMSO solution in presence of the cell-BiB. Characterization with FT-IR, NMR, and GPC measurements showed that there obtained a graft copolymer with cellulose backbone and PDMA side chains (cell-PDMA) in well-defined structure. The proteins adsorption studies showed that the cellulose membranes modified by the as-prepared cell-PDMA copolymer owns good protein adsorption resistancet.展开更多
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
Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyry...Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyryl bromide(BriB-Br)to obtain efficient macroinitiator for ATRP.And the macroinitiator was grafted with HEMA in water aqueous using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine(PMDETA)as catalyst system.The effects of monomer concentration,the proportion of CuBr and PMDETA,grafting temperature and time on the silk grafting were discussed,and the optimal grafting technology was obtained.FT-IR characterization of the grafted silk showed a peak corresponding to HEMA,which indicated that HEMA was grafted onto the surface of silk.ATRP method could be applied on the silk modification and this technique provided a new way for silk grafting.展开更多
Organic nanophotocatalysts are promising candidates for solar fuels production,but they still face the challenge of unfavorable geminate recombination due to the limited exciton diffusion lengths.Here,we introduce a b...Organic nanophotocatalysts are promising candidates for solar fuels production,but they still face the challenge of unfavorable geminate recombination due to the limited exciton diffusion lengths.Here,we introduce a binary nanophotocatalyst fabricated by blending two polymers,PS-PEG5(PS)and PBT-PEG5(PBT),with matched absorption and emission spectra,enabling a Forster resonance energy transfer(FRET)process for enhanced photocatalysis.These heterostructure nanophotocatalysts are processed using a facile and scalable flash nanoprecipitation(FNP)technique with precious kinetic control over binary nanoparticle formation.The resulting nanoparticles exhibit an exceptional photocatalytic hydrogen evolution rate up to 65 mmol g^(-1) h^(-1),2.5 times higher than that single component nanoparticles.Characterizations through fluorescence spectra and transient absorption spectra confirm the hetero-energy transfer within the binary nanoparticles,which prolongs the excited-state lifetime and extends the namely“effective exciton diffusion length”.Our finding opens new avenues for designing efficient organic photocatalysts by improving exciton migration.展开更多
Reversible addition-fragmentation chain transfer(RAFT) mediated grafting of acrylonitrile onto Polyethylene/Poly(ethylene terephthalate)(PE/PET) composite fibers was performed using γ-irradiation as the initial sourc...Reversible addition-fragmentation chain transfer(RAFT) mediated grafting of acrylonitrile onto Polyethylene/Poly(ethylene terephthalate)(PE/PET) composite fibers was performed using γ-irradiation as the initial source at ambient temperature. Different initial concentrations of 2-cyanoprop-2-yl dithiobenzonate were used as the chain transfer agent. The kinetics of graft polymerization is in accordance with the living RAFT polymerization. The successful grafting of acrylonitrile is proved by Fourier transform infrared spectroscopy analysis.The results of monofilament tensile test show that mechanical properties of the fibers change slightly after grafting. Scanning electronic microscopy images of the fibers show that the surface of RAFT grafted fibers is smoother than that of fibers grafted conventionally.展开更多
The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-b...The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by ~1H-NMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.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
Electron transfer processes at polymer electrolyte/electrode interfaces play a central role in modern electrochemical devices of energy conversion,however,current understanding of electron transfers through electroche...Electron transfer processes at polymer electrolyte/electrode interfaces play a central role in modern electrochemical devices of energy conversion,however,current understanding of electron transfers through electrochemical interfaces was established exclusively based on the studies of liquid/solid electrochemical interfaces.Thus,similarities and differences of liquid and polymer electrolyte/electrode interfaces need to be mapped out to guide the design of device level electrochemical interfaces.In this work,we employ the sulfonate adsorption/desorption as a probe reaction to understand the electron-transfer steps in polymer and liquid electrolytes.Through cyclic voltametric investigations on the well-define single-crystal Pd_(ML)Pt(111)electrode,we demonstrate that the oxidative adsorption and reductive desorption of sulfonates at the polymer electrolyte/electrode interface are chemically distinct from those in liquid electrolytes,with the former occurring mostly via the proton-coupled pathway while the latter proceeding mainly through the solvation-mediated pathway.Importantly,the sulfonate adsorption/desorption behaviors of alkylsulfonates become increasingly similar to those in Nafion with longer alkyl chains,suggesting that the interfacial hydrophobicity and solvation environment conferred by the perfluorinated polymer play a decisive role in the electron-transfer mechanism.Results reported in this study highlight the mechanistic distinctions between electron-transfer processes at electrochemical interfaces involving polymer and liquid electrolytes,and provide a framework for understanding electron-transfer processes at polymer electrolyte/electrode interfaces.展开更多
A simple and effective method for surface molecularly imprinted composite membranes （MICMs） for artemisinin （Ars） based on regenerated cellulose membranes was first prepared through surface- initiated atom transfe...A simple and effective method for surface molecularly imprinted composite membranes （MICMs） for artemisinin （Ars） based on regenerated cellulose membranes was first prepared through surface- initiated atom transfer radical polymerization （ATRP）, and the as-prepared MICMs were then evaluated as adsorbents for selective recognition and separation of Ars molecules. Batch rebinding studies were conducted to determine the specific adsorption equilibrium, kinetics and selective permeation performance. The adsorption capacity of MICMs toward Ars by the Langmuir isotherm model was 2.008 mgg-1, which was nearly 5.0 times higher than non-molecularly imprinted composite membranes （NICMs）. The kinetic property of MICMs was well-fitted by the pseudo-second-order rate equation. The selective permeation experiments were successfully investigated to prove the excellent selective permeation performance for Ars than the competitive analog （artemether）.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
A novel liquid hyperbranched polyether epoxy （HBPEE） based on commercially available hydroquinone （HQ） and 1,1,1-trihydroxymethylpropane triglycidyl ether （TMPGE） was synthesized through an A2 ＋ B3 one-step pro...A novel liquid hyperbranched polyether epoxy （HBPEE） based on commercially available hydroquinone （HQ） and 1,1,1-trihydroxymethylpropane triglycidyl ether （TMPGE） was synthesized through an A2 ＋ B3 one-step proton transfer polymerization. In order to improve the toughness, the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A （DGEBA） in different ratios to form hybrids and cured with triethylenetetramine （TETA）. Thermal and mechanical properties of the cured hybrids were evaluated. Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at 〈 20 wt% loading, without compromising the tensile strength. However, the glass transition temperature （Tg） of the cured hybrids decreases with increasing HBPEE content. Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE. The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness. Furthermore, based on the morphology of fractured surfaces and the single Tg in each hybrid, no sign of phase separation was found in the cured hybrid systems. As a result, the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.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
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.
基金Supported by the National Natural Science Foundation of China(Nos.21773240 and 22173103)the University of the Chinese Academy of Sciences and Beijing National Laboratory for Molecular Sciences(No.BNLMS2023014)。
文摘Photoredox-mediated reversible-deactivation radical polymerization(RDRP)is an effective approach to synthesize polymers with defined composition and architecture.Current photoinduced RDRP primarily depends on outer-sphere electron transfer or homolysis mechanisms.Herein,we describe an example of iodine-mediated RDRP facilitated by photoinduced charge transfer complex(CTC)catalysis.The approach uses cheap and easily accessible N^(-)heterocyclic nitrenium salt(NHN^(+)...I^(-))as the photoactive CTC.Upon the irradiation of visible light,NHN^(+)...I^(-)undergoes single electron transfer to generate NHN·and I·radicals.The NHN·radical activates dormant Pn-I polymers via inner-sphere single electron transfer,leading to the propagating Pn·radical for chain growth and the I^(-)anion for recovering the CTC,and the I·radical deactivates the polymerization via coupling with Pn·.
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.
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Supported by the National Basic Research Program of China(2009CB724706)
文摘A block copolymer of 2-dimethylaminoethyl methacrylate(DMAEMA) and glycidyl methacrylate(GMA)was grafted onto the surface of magnetic nanoparticles(Fe3O4) via atom transfer radical polymerization.The resultant PGMA-b-PDMAEMA-grafted-Fe3O4 magnetic nanoparticles with amino and epoxy groups were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermo-gravimetric analysis, and scanning electron microscopy. Lipase from Burkholderia cepacia was successfully immobilized onto the magnetic nanoparticles by physical adsorption and covalent bonding. The immobilization capacity of the magnetic particles is 0.5 mg lipase per mg support, with an activity recovery of up to 43.1% under the optimum immobilization condition. Biochemical characterization shows that the immobilized lipase exhibits improved thermal stability, good tolerance to organic solvents with high lg P, and higher p H stability than the free lipase at p H 9.0. After six consecutive cycles, the residual activity of the immobilized lipase is still over55% of its initial activity.
文摘In homogeneous media, N,N-Dimethylacrylamide (DMA) was grafted copolymerization to cellulose by a metal-catalyzed atom transfer radical polymerization (ATRP) process. First, cellulose was dissolved in DMAc/LiCl system, and it reacted with 2-bromoisobutyloyl bromide (BiBBr) to produce macroinitiator (cell-BiB). Then DMA was polymerized to the cellulose backbone in a homogeneous DMSO solution in presence of the cell-BiB. Characterization with FT-IR, NMR, and GPC measurements showed that there obtained a graft copolymer with cellulose backbone and PDMA side chains (cell-PDMA) in well-defined structure. The proteins adsorption studies showed that the cellulose membranes modified by the as-prepared cell-PDMA copolymer owns good protein adsorption resistancet.
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National Natural Science Foundation of China(No.50673071,No.50973079)Natural Science Fund for Colleges and Universities in Jiangsu Province,China(No.07KJD540188,No.09KJA540001)
文摘Silk was grafted using 2-hydroxyethyl methacrylate(HEMA)by atom transfer radical polymerization(ATRP)method.The amino groups and hydroxyl groups on the side chains of the silk fibroin was reacted with 2-bromoisobutyryl bromide(BriB-Br)to obtain efficient macroinitiator for ATRP.And the macroinitiator was grafted with HEMA in water aqueous using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine(PMDETA)as catalyst system.The effects of monomer concentration,the proportion of CuBr and PMDETA,grafting temperature and time on the silk grafting were discussed,and the optimal grafting technology was obtained.FT-IR characterization of the grafted silk showed a peak corresponding to HEMA,which indicated that HEMA was grafted onto the surface of silk.ATRP method could be applied on the silk modification and this technique provided a new way for silk grafting.
基金supported by National Natural Science Foundation of China(NSFC,22338006,92356301,9235630033 and 22375062)Shanghai Municipal Science and Technology Major Project(21JC1401700)+4 种基金Shanghai Pilot Program for Basic Research(22TQ1400100-10)Fundamental Research Funds for the Central UniversitiesShanghai Pujiang Program(22PJ1402400)“Chenguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(22CGA32)the Young Elite Scientists Sponsorship Program by CAST(2023QNRC001).
文摘Organic nanophotocatalysts are promising candidates for solar fuels production,but they still face the challenge of unfavorable geminate recombination due to the limited exciton diffusion lengths.Here,we introduce a binary nanophotocatalyst fabricated by blending two polymers,PS-PEG5(PS)and PBT-PEG5(PBT),with matched absorption and emission spectra,enabling a Forster resonance energy transfer(FRET)process for enhanced photocatalysis.These heterostructure nanophotocatalysts are processed using a facile and scalable flash nanoprecipitation(FNP)technique with precious kinetic control over binary nanoparticle formation.The resulting nanoparticles exhibit an exceptional photocatalytic hydrogen evolution rate up to 65 mmol g^(-1) h^(-1),2.5 times higher than that single component nanoparticles.Characterizations through fluorescence spectra and transient absorption spectra confirm the hetero-energy transfer within the binary nanoparticles,which prolongs the excited-state lifetime and extends the namely“effective exciton diffusion length”.Our finding opens new avenues for designing efficient organic photocatalysts by improving exciton migration.
基金Supported by the National Natural Science Foundation of China(Nos.11475246 and 11175234)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA02030205)
文摘Reversible addition-fragmentation chain transfer(RAFT) mediated grafting of acrylonitrile onto Polyethylene/Poly(ethylene terephthalate)(PE/PET) composite fibers was performed using γ-irradiation as the initial source at ambient temperature. Different initial concentrations of 2-cyanoprop-2-yl dithiobenzonate were used as the chain transfer agent. The kinetics of graft polymerization is in accordance with the living RAFT polymerization. The successful grafting of acrylonitrile is proved by Fourier transform infrared spectroscopy analysis.The results of monofilament tensile test show that mechanical properties of the fibers change slightly after grafting. Scanning electronic microscopy images of the fibers show that the surface of RAFT grafted fibers is smoother than that of fibers grafted conventionally.
基金This project was supported in part by the Ministry of Education of China (No. JG2000-11).
文摘The radical copolymerization of methyl methacrylate and 2-hydroxyethyl methacrylate was carried out via atomtransfer radical polymerization (ATRP) initiated by ethyl 2-bromoisobutyrate and catalyzed by CuBr/2,2'-bipyridinecomplex. This polymerization proceeds in a living fashion with controlled molecular weight and low polydispersity. Theobtained copolymer was esterified with 2-bromoisobutylryl bromide yielding a macroinitiator, poly(methyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-(2-bromoisobutyryloxy)ethyl methacrylate), and its structure was characterized by ~1H-NMR. This macroinitiator was used for ATRP of styrene to synthesize poly(methyl methacrylate)-graft-polystyrene. Themolecular weight of graft copolymer increased with the monomer conversion, and the polydispersity remained relatively low.The individual grafted polystyrene chains were cleaved from the macroinitiator backbone by hydrolysis and the hydrolyzed product was characterized by ~1H-NMR and GPC.
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supported by the National Key R&D Program of China(No.2021YFA1501003)。
文摘Electron transfer processes at polymer electrolyte/electrode interfaces play a central role in modern electrochemical devices of energy conversion,however,current understanding of electron transfers through electrochemical interfaces was established exclusively based on the studies of liquid/solid electrochemical interfaces.Thus,similarities and differences of liquid and polymer electrolyte/electrode interfaces need to be mapped out to guide the design of device level electrochemical interfaces.In this work,we employ the sulfonate adsorption/desorption as a probe reaction to understand the electron-transfer steps in polymer and liquid electrolytes.Through cyclic voltametric investigations on the well-define single-crystal Pd_(ML)Pt(111)electrode,we demonstrate that the oxidative adsorption and reductive desorption of sulfonates at the polymer electrolyte/electrode interface are chemically distinct from those in liquid electrolytes,with the former occurring mostly via the proton-coupled pathway while the latter proceeding mainly through the solvation-mediated pathway.Importantly,the sulfonate adsorption/desorption behaviors of alkylsulfonates become increasingly similar to those in Nafion with longer alkyl chains,suggesting that the interfacial hydrophobicity and solvation environment conferred by the perfluorinated polymer play a decisive role in the electron-transfer mechanism.Results reported in this study highlight the mechanistic distinctions between electron-transfer processes at electrochemical interfaces involving polymer and liquid electrolytes,and provide a framework for understanding electron-transfer processes at polymer electrolyte/electrode interfaces.
基金financially supported by the National Natural Science Foundation of China(Nos.21077046,21107037,21176107,21174057,2100403,21207051)National key basic research development program(973 Program,No. 2012CBB21500)+2 种基金Ph.D.Programs Foundation of Ministry of Education of China(No.20123227120015)Natural Science Foundation of Jiangsu Province(Nos.BK2011461,SBK2011459, BK2011514)China Postdoctoral Science Foundation funded project(Nos.2012M511220,2013M530240)
文摘A simple and effective method for surface molecularly imprinted composite membranes （MICMs） for artemisinin （Ars） based on regenerated cellulose membranes was first prepared through surface- initiated atom transfer radical polymerization （ATRP）, and the as-prepared MICMs were then evaluated as adsorbents for selective recognition and separation of Ars molecules. Batch rebinding studies were conducted to determine the specific adsorption equilibrium, kinetics and selective permeation performance. The adsorption capacity of MICMs toward Ars by the Langmuir isotherm model was 2.008 mgg-1, which was nearly 5.0 times higher than non-molecularly imprinted composite membranes （NICMs）. The kinetic property of MICMs was well-fitted by the pseudo-second-order rate equation. The selective permeation experiments were successfully investigated to prove the excellent selective permeation performance for Ars than the competitive analog （artemether）.
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.
基金supported by the Natural Science Foundation of Beijing(No.2092023)National Natural Science Foundation of China(No.51173012)the Fundamental Research Funds for the Central Universities(No.ZZ0912)
文摘A novel liquid hyperbranched polyether epoxy （HBPEE） based on commercially available hydroquinone （HQ） and 1,1,1-trihydroxymethylpropane triglycidyl ether （TMPGE） was synthesized through an A2 ＋ B3 one-step proton transfer polymerization. In order to improve the toughness, the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A （DGEBA） in different ratios to form hybrids and cured with triethylenetetramine （TETA）. Thermal and mechanical properties of the cured hybrids were evaluated. Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at 〈 20 wt% loading, without compromising the tensile strength. However, the glass transition temperature （Tg） of the cured hybrids decreases with increasing HBPEE content. Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE. The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness. Furthermore, based on the morphology of fractured surfaces and the single Tg in each hybrid, no sign of phase separation was found in the cured hybrid systems. As a result, the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.
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.
