Copolymers of fluoroethylene and vinyl ethers(FEVE)are soluble and curable at relatively low temperature,and are used as high-performance coatings and paints.Currently,most market-available FEVE products obtained thro...Copolymers of fluoroethylene and vinyl ethers(FEVE)are soluble and curable at relatively low temperature,and are used as high-performance coatings and paints.Currently,most market-available FEVE products obtained through solution polymerization contain a large fraction of organic solvent,and hence,volatile organic compound(VOC)emissions cause environmental issues.In this study,the emulsion copolymerization of chlorotrifluoroethylene(CTFE)and vinyl ethers using an environmentally friendly emulsification system to produce waterborne FEVE was investigated.In addition to mixed nonionic and ionic surfactants,macromolecular monomer with double bond and polyoxyethylene segments were used in the emulsification system.The effect of adding macromolecular monomer and polyoxyethylene segment length of the nonionic surfactant on emulsion copolymerization were analyzed.An optimized emulsifier system for FEVE is proposed,and the prepared FEVE latexes exhibit excellent storage stability and film formation ability.展开更多
To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polym...To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.展开更多
Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effectiv...Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.展开更多
Eucalyptus staigeriana essential oil(EsEO)has well-known anthelmintic activity in small ruminants.However,its volatility limits its therapeutic action.The aim of this study was to develop a water-in-oil sodium alginat...Eucalyptus staigeriana essential oil(EsEO)has well-known anthelmintic activity in small ruminants.However,its volatility limits its therapeutic action.The aim of this study was to develop a water-in-oil sodium alginatebased nanoemulsion with an effective in vitro effect on the eggs and larvae of Haemonchus contortus,a gastrointestinal parasite of sheep and goats.Four oil-in-water sodium alginate-based emulsions were prepared using a high-energy method with different proportions of Tween 80,EsEO,and sodium alginate(ALG)4%.The physical-chemical characterization included stability,particle size,zeta potential and infrared spectra.The effects of the emulsions were evaluated against H.contortus via the egg hatching test(EHT)and larval development test(LDT).The results showed that the emulsions were stable over 7 days,nanometer scale particles(218.8 to 371.5 nm)predominating and with negative zeta potentials(−28.9 to−46.9 mV).All four emulsions were more effective than EsEO in the EHT,with 50%effective concentrations(EC50)of 0.088 to 0.15 mg/mL for the emulsions and 0.308 mg/mL for EsEO.However,in the LDT,the emulsions and essential oil had similar effects,with EC50 values of 3.91 to 4.60 mg/mL for the emulsions and 4.17 mg/mL for EsEO.Emulsion 2,with low Tween 80/EsEO and ALG/EsEO ratios,was considered better overall in terms of physical,chemical and anthelmintic assessment and is a promising candidate for further in vivo assays against adult H.contortus.展开更多
Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catal...Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.展开更多
Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford prod...Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.展开更多
Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surfa...Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.展开更多
Organo-fly ash （OFA） was prepared with pretreated fly ash （FA） and hexadecyltrimethyl ammonium bromide （HDTMAB）, and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at dif...Organo-fly ash （OFA） was prepared with pretreated fly ash （FA） and hexadecyltrimethyl ammonium bromide （HDTMAB）, and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios （2.0 wt%, 5.0 wt%, 10.0 wt%, 15.0 wt% and 20.0 wt%） in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier. A polymerization procedure was supposed. The electrical conductivities of the composites were tested by the four-probe technique. The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction, respectively. Morphologies of FA, OFA and the composites were observed by SEM. The element analysis was performed by energy dispersive spectrometry. The thermal stability of the composites was analyzed by TGA. The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA, and the lowest value was 0.62 S/cm. HDTMAB and PAn were just adsorbed on the surface of FA and OFA, respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA. The surface became smoother after organification of FA by using HDTMAB, and its content on FA surfaces was about 26.9 wt%. The core/shell structure of the composite was observed by SEM analysis. The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system, the heat stability of PAn was increased by decreasing 31.8 wt% of weight loss after introducing 20 wt% of OFA.展开更多
Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant （bis-[2-（F-hexyl）ethyl]phosphate sodium）, water-soluble/CO2-insoluble acr...Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant （bis-[2-（F-hexyl）ethyl]phosphate sodium）, water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N＇-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 （w/c） microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2＇-azo-bisisobutyronitrile （AIBN）, cross-linked poly（acryloxyethyltrimethyl ammonium chloride） particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained.展开更多
Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl ...Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.展开更多
The particle size distribution of polymer always develops in emulsion polymerization systems,and certain key phenomena/mechanisms as well as properties of the final product are significantly affected by this distribut...The particle size distribution of polymer always develops in emulsion polymerization systems,and certain key phenomena/mechanisms as well as properties of the final product are significantly affected by this distribution.This review mainly focuses on the measurement methods of particle size distribution rather than average particle size during the emulsion polymerization process,including the existing off-line,on-line,and in-line measurement methods.Moreover,the principle,resolution,performance,advantages,and drawbacks of various methods for evaluating particle size distribution are contrasted and illustrated.Besides,several possible development directions or solutions of the in-line measurement technology are explored.展开更多
Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases an...Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases anddisappears at conversions greater than 30%. Scanning electron micrographs show that PVC grains are composed of looselycoalesced primary particles, especially for PVC resins prepared in the presence of poly(vinyl alcohol) dispersant. The size ofprimary particles increases and porosity decreases with the increase of conversion. In view of the particle features of PVCresin, a particle formation mechanism including the formation of primary particles and grains is proposed. The formationprocess of primary particles includes the formation of particle nuclei, coalescence of particle nuclei to form primary particles,and growth of primary particles. PVC grains are formed by the coagulation of primary particles. The loose coalescence ofprimary particles is caused by the colloidal stability of primary particles and the low swelling degree of vinyl chloride in the primary particles.展开更多
Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle s...Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.展开更多
Monodisperse functional polymer microspheres with different particle size and with clean surface were prepared by batch soap-free emulsion polymerization of styrene, methyl methacrylate and acrylic acid in the presenc...Monodisperse functional polymer microspheres with different particle size and with clean surface were prepared by batch soap-free emulsion polymerization of styrene, methyl methacrylate and acrylic acid in the presence of salts, and the influences of type and amount of electrolytes on polymerization process and particle morphology were investigated. Results showed that there was a critical concentration for different electrolyte to make polymerization process and the resultant emulsion stable, and the particle size increased with the increase of electrolyte concentration. The effect of metal ions was Ca^2＋〉〉K^＋〉Na^＋〉Li^＋, and the effect of haloids was Br〉Cl〉F. Keywords： Electrolyte, soap-free emulsion polymerization, polystyrene, latex particle morphology.展开更多
The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated. The ...The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated. The original latex particles with narrow size distribution were synthesized by a new sequence emulsifier-free/emulsifier emulsion copolymerization of styrene (St) and methacrylic acid (MAA). Results indicated that the pore size decreased and the pore number increased with the increase of SDBS amount, and the morphology of the posttreated latex particles was also significantly influenced by the introducing time of SDBS in the preparation of the original latex particles, and a suitable introducing time was 3 h of polymerization. (c) 2007 Cheng You Kan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
Poly(styrene-co-glycidyl methacrylate) latex microspheres with uniform size and high-density epoxy groups on the surface were prepared by soap-free emulsion polymerization with batch wise operation mode in the presenc...Poly(styrene-co-glycidyl methacrylate) latex microspheres with uniform size and high-density epoxy groups on the surface were prepared by soap-free emulsion polymerization with batch wise operation mode in the presence of 2.2′- azobis(2-methylpropionamidine) dihydrochloride as an initiator.The kinetics of soap-free emulsion polymerization and the effects of polymerization factors were examined.In addition,the optimum polymerization conditions of poly(styrene-co- glycidyl methacrylate) latex microspheres for...展开更多
Submicron-sized peanut-shaped poly（methyl methacrylate）/polystyrene （PMMA/PS） particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed p...Submicron-sized peanut-shaped poly（methyl methacrylate）/polystyrene （PMMA/PS） particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed particles. The obtained peanut- shaped particles showed a novel internal morphology： PS phase formed one domain which linked to the other domain having PMMA core encased by PS shell.展开更多
Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast...Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl(n BHMA) and tert-butyl(t BHMA) α-hydroxymethyl acrylate, and thus possessing different water solubilities were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of n BHMA and t BHMA employing poly(ethylene glycol) macromolecular chain transfer agents(macro-CTAs, PEG45-CTA, and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for t BHMA, which has a higher water solubility than that of n BHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.展开更多
One of the major challenges associated with fuel cells is the design of highly efficient electrocatalysts to reduce the high overpotential of the oxygen reduction reaction (ORR). Here we report Polyaniline (PANI) base...One of the major challenges associated with fuel cells is the design of highly efficient electrocatalysts to reduce the high overpotential of the oxygen reduction reaction (ORR). Here we report Polyaniline (PANI) based micro/nanomaterials with or without transition metals, prepared by the emulsion polymerization and subsequent heat treatment. PANI microspheres with the diameter of about 0.7 mu m have been prepared in basic (NH3 solution) condition, using two different types of surfactant (CTAB, SDS) as the stabilizer, ammonium persulphate (APS) as oxidant with aniline/surfactants molar ratio at 1/1 under the hydrothermal treatment. PANI nanorods, Fe-PANI, and Fe-Co-PANI have been synthesized in acidic (HCI) medium with aniline/surfactants molar ratio at 1/2 and polymerization carried out without stirring for 24 h. Products mainly Fe-Co-PANI have shown high current density with increasing sweep rate and excellent specific capacitance 1753 F/g at the scan rate of 1 mV/s. Additionally, it has shown high thermal stability by thermogravimetric analysis (TGA). Fe-PANI has been investigated for excellent performance toward ORR with four electron selectivity in the basic electrolyte. The PANI-based catalysts from emulsion polymerization demonstrate that the method is valuable for making non-precious metal heterogeneous electrocatalysts for ORR or energy storage and conversion technology. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.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
基金financially supported by the joint lab of Shanghai Huayi 3F New Materials Co.,Ltd.Donghua University。
文摘Copolymers of fluoroethylene and vinyl ethers(FEVE)are soluble and curable at relatively low temperature,and are used as high-performance coatings and paints.Currently,most market-available FEVE products obtained through solution polymerization contain a large fraction of organic solvent,and hence,volatile organic compound(VOC)emissions cause environmental issues.In this study,the emulsion copolymerization of chlorotrifluoroethylene(CTFE)and vinyl ethers using an environmentally friendly emulsification system to produce waterborne FEVE was investigated.In addition to mixed nonionic and ionic surfactants,macromolecular monomer with double bond and polyoxyethylene segments were used in the emulsification system.The effect of adding macromolecular monomer and polyoxyethylene segment length of the nonionic surfactant on emulsion copolymerization were analyzed.An optimized emulsifier system for FEVE is proposed,and the prepared FEVE latexes exhibit excellent storage stability and film formation ability.
基金the support from the Jiangsu Provincial Senior Talent Program (Dengfeng,Jiangsu University)the support from the National Key R&D Program of China (No.2024YFB3612600)+3 种基金the National Natural Science Foundation of China (Nos.22275098,62288102)Basic Research Program of Jiangsu (No.BK20243057)the Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (No.NY222097)the National Natural Science Foundation of China (No.62205035)。
文摘To precisely control intrachain π-electron delocalization and interchain interaction simultaneously is the prerequisite to obtain stable and efficient deep-blue light-emitting p-n polymer semiconductors for the polymer light-emitting diodes(PLEDs).Herein,we introduced the steric carbazole-fluorene nanogrid into light-emitting diphenyl sulfone-based p-n polymer semiconductors(PG and PDG) via metal-free C-N coupling polymerization for the fabrication of deep-blue PLEDs.The steric,rigid and twisted configuration between nanogrid and diphenyl sulfone in PG and PDG present the unique characteristic of large steric hindrance interaction to suppress interchain aggregation in solid state.Due to the different length of electron-deficient diphenyl sulfone monomers,PG showed a deep-blue emission with a maximum peak at 428 nm but red-shifted to 480 nm for the PDG films.Interestingly,similar deep-blue emission behavior of PG in diluted non-polar solution and films suggested the extremely weak interchain aggregation.Finally,PLEDs based on PG are fabricated with a stable deep-blue emission of CIE(0.15,0.10),and corresponding EL spectral profile is also completely identical to PL ones of diluted solution,revealed the intrachain emission without obvious interchain excited state,confirmed effectiveness of the steric hindrance functionalization of nanogrid in p-n polymer semiconductor for deep-blue light-emitting organic optoelectronics.
基金financially supported by the National Natural Science Foundation of China(No.52473338)the National Natural Science Foundation of China(Nos.52173004 and 51873055)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0540000)Advanced Materials-National Science and Technology Major Project(No.2025ZD0614000)Hebei Natural Science Foundation(No.E2022202015)Anhui Province Science and Technology Innovation Tackling Key Project(No.202423i08050025)。
文摘Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.
基金supported by Conselho Nacional de Desenvolvimento Cientifico eTecnologico(CNPq)(grant No.142165/2018-2)Mr.Araujo-Filho had a doctoral scholarship and Dr.Bevilaqua has a research fellowship(grant No.305911/2019-8)from CNPq.
文摘Eucalyptus staigeriana essential oil(EsEO)has well-known anthelmintic activity in small ruminants.However,its volatility limits its therapeutic action.The aim of this study was to develop a water-in-oil sodium alginatebased nanoemulsion with an effective in vitro effect on the eggs and larvae of Haemonchus contortus,a gastrointestinal parasite of sheep and goats.Four oil-in-water sodium alginate-based emulsions were prepared using a high-energy method with different proportions of Tween 80,EsEO,and sodium alginate(ALG)4%.The physical-chemical characterization included stability,particle size,zeta potential and infrared spectra.The effects of the emulsions were evaluated against H.contortus via the egg hatching test(EHT)and larval development test(LDT).The results showed that the emulsions were stable over 7 days,nanometer scale particles(218.8 to 371.5 nm)predominating and with negative zeta potentials(−28.9 to−46.9 mV).All four emulsions were more effective than EsEO in the EHT,with 50%effective concentrations(EC50)of 0.088 to 0.15 mg/mL for the emulsions and 0.308 mg/mL for EsEO.However,in the LDT,the emulsions and essential oil had similar effects,with EC50 values of 3.91 to 4.60 mg/mL for the emulsions and 4.17 mg/mL for EsEO.Emulsion 2,with low Tween 80/EsEO and ALG/EsEO ratios,was considered better overall in terms of physical,chemical and anthelmintic assessment and is a promising candidate for further in vivo assays against adult H.contortus.
基金financial support from the National Natural Science Foundation of China(Nos.22401274,U23B6011)the Jilin Provincial Science and Technology Department Program(No.20250102070JC)。
文摘Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.
基金financially supported by National Key R&D Program Young Scientists Project(No.2023YFC3903100)the National Natural Science Foundation of China(No.22322503)analytical and testing assistance from the Analysis and Testing Center of HUST。
文摘Switchable polymerization is emerging as a powerful tool to construct block copolymers directly from mixtures of monomers.However,current achievements typically iterate between two polymerization cycles to afford products with fixed sequences and compositions.Herein,we report the triethylborane/1,8-diazabicyclo[5.4.0]undec-7-ene(Et_3B/DBU)pair-mediated four-component switchable polymerization of propylene oxide(PO),CO_(2),phthalic anhydride(PA),and racemic lactide(rac-LA),which enables the on-demand synthesis of four different block copolymers,i.e.,poly(propylene phthalate)-b-polylactide(PPE-b-PLA),PPE-b-PLA-b-poly(propylene carbonate)(PPC),PPE-b-PPC-b-PLA,and PPE-b-PPCb-poly(propylene oxide)(PPO),through rationally modulating the Lewis pair(LP)ratio.Core to this protocol is that increasing the loading of Et_(3)B accelerates the ring-opening of PO while impeding the reactivity of rac-LA,thus allowing for fine-tuning of the thermodynamic and kinetic of the switchable polymerization.Therefore,the four polymerization cycles involving PO/PA ring-opening copolymerization(ROCOP),PO/CO_(2) ROCOP,rac-LA ring-opening polymerization(ROP),and PO ROP can be connected and discriminated in precisely programmed manners.
基金This research was financially supported by the Key Project of China Educational Ministry (No. 103064)the Doctoral Foundation of University (No. 20020246031)
文摘Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.
基金supported by the Shaanxi Provincial Education Department(No.09JK528) and Program of Shaanxi Key Subject
文摘Organo-fly ash （OFA） was prepared with pretreated fly ash （FA） and hexadecyltrimethyl ammonium bromide （HDTMAB）, and the composites composed of OFA and polyaniline were obtained by emulsion polymerization at different OFA weight ratios （2.0 wt%, 5.0 wt%, 10.0 wt%, 15.0 wt% and 20.0 wt%） in the presence of dodecylbenzenesulfonic acid as dopant and emulsifier. A polymerization procedure was supposed. The electrical conductivities of the composites were tested by the four-probe technique. The chemical structure and crystallinity of the composites were confirmed by FT-IR and X-ray diffraction, respectively. Morphologies of FA, OFA and the composites were observed by SEM. The element analysis was performed by energy dispersive spectrometry. The thermal stability of the composites was analyzed by TGA. The results showed that the electrical conductivity of the composites decreased with increasing the feed weight ratio of OFA, and the lowest value was 0.62 S/cm. HDTMAB and PAn were just adsorbed on the surface of FA and OFA, respectively according to the physical adsorption without destroying the crystalline structure of FA or OFA. The surface became smoother after organification of FA by using HDTMAB, and its content on FA surfaces was about 26.9 wt%. The core/shell structure of the composite was observed by SEM analysis. The composites showed a higher thermal stability than pure PAn by introduction of OFA into this polymerization system, the heat stability of PAn was increased by decreasing 31.8 wt% of weight loss after introducing 20 wt% of OFA.
基金This work was financially supported by the STC Program of the US National Science Foundation under Agreement No.CHE-9876674.
文摘Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant （bis-[2-（F-hexyl）ethyl]phosphate sodium）, water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N＇-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 （w/c） microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2＇-azo-bisisobutyronitrile （AIBN）, cross-linked poly（acryloxyethyltrimethyl ammonium chloride） particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained.
文摘Methyl methacrylate (MMA) emulsion polymerization in the presence of nanometer calcium carbonate(nano-CaCO3) surface modified with γ-methacryloxypropyltrimethoxysilane (MPTMS) was carried out to prepare poly (methyl methacrylate) (PMMA)/nano-CaCO3 composite. The reaction between nano-CaCO3 and MPTMS, and the grafting of PMMA onto nano-CaCO3 were confirmed by infrared spectrum. The grafting ratio and grafting efficiency of PMMA on nano-CaCO3 modified with MPTMS were much higher than that on nano-CaCO3 modified with stearic acid. The grafting ratio of PMMA increased as the weight ratio between MMA and nano-CaCO3 increased, while the grafting efficiency of PMMA decreased. Transmission electron micrograph showed that nano-CaCO3 covered with PMMA was formed by in-situ emulsion polymerization.
基金The National Key Research and Development Program(2020YFA0906804)the National Natural Science Foundation of China(22078325,22035007,91934301)+1 种基金the NSFC-EU project(31961133018)the Special Project of Strategic Leading Science and Technology,CAS(XDC06010302)are gratefully acknowledged.
文摘The particle size distribution of polymer always develops in emulsion polymerization systems,and certain key phenomena/mechanisms as well as properties of the final product are significantly affected by this distribution.This review mainly focuses on the measurement methods of particle size distribution rather than average particle size during the emulsion polymerization process,including the existing off-line,on-line,and in-line measurement methods.Moreover,the principle,resolution,performance,advantages,and drawbacks of various methods for evaluating particle size distribution are contrasted and illustrated.Besides,several possible development directions or solutions of the in-line measurement technology are explored.
基金The project is supported by the National Natural Science Foundation of China (No. 29906009)
文摘Suspended emulsion polymerization was used to prepare poly(vinyl chloride) (PVC) resin. Fine PVC particleswere formed at low polymerization conversions. The amount of fine panicles decreases as conversion increases anddisappears at conversions greater than 30%. Scanning electron micrographs show that PVC grains are composed of looselycoalesced primary particles, especially for PVC resins prepared in the presence of poly(vinyl alcohol) dispersant. The size ofprimary particles increases and porosity decreases with the increase of conversion. In view of the particle features of PVCresin, a particle formation mechanism including the formation of primary particles and grains is proposed. The formationprocess of primary particles includes the formation of particle nuclei, coalescence of particle nuclei to form primary particles,and growth of primary particles. PVC grains are formed by the coagulation of primary particles. The loose coalescence ofprimary particles is caused by the colloidal stability of primary particles and the low swelling degree of vinyl chloride in the primary particles.
基金Supported by the National Natural Science Foundation of China (No. 29906009).
文摘Suspended emulsion polymerization of vinyl chloride was carried out in a 5 L autoclave. The influence of agitation, polymerization conversion, dispersant and surfactant on the average particle size (PS) and particle size distribution (PSD), particle morphology and porosity of polyvinyl chloride (PVC) resin was investigated. It showed that the agitator had great influence on the smooth operation of polymerization, PS and PSD. The PS increased and PSD became narrow as polymerization conversion became high. The porosity decreased with the increase of conversion. A convenient choice of additives, both dispersants and non-ionic surfactants, allows one to adjust PS and PSD. The PS decreased with the addition of polyvinyl alcohol or hydroxypropyl methylcellulose dispersants,and increased with the addition of Span surfactants. The addition of dispersants or surfactants also affected the morphology and porosity of resin, and PVC resin with looser agglomeration and homogeneous distribution of primary particles was prepared.
文摘Monodisperse functional polymer microspheres with different particle size and with clean surface were prepared by batch soap-free emulsion polymerization of styrene, methyl methacrylate and acrylic acid in the presence of salts, and the influences of type and amount of electrolytes on polymerization process and particle morphology were investigated. Results showed that there was a critical concentration for different electrolyte to make polymerization process and the resultant emulsion stable, and the particle size increased with the increase of electrolyte concentration. The effect of metal ions was Ca^2＋〉〉K^＋〉Na^＋〉Li^＋, and the effect of haloids was Br〉Cl〉F. Keywords： Electrolyte, soap-free emulsion polymerization, polystyrene, latex particle morphology.
文摘The effects of ionic emulsifier, sodium dodecylbenzene sulfate (SDBS), on the formation of the multihollow structures in sub-micron sized polymer particles produced by alkali/acid posttreatment were investigated. The original latex particles with narrow size distribution were synthesized by a new sequence emulsifier-free/emulsifier emulsion copolymerization of styrene (St) and methacrylic acid (MAA). Results indicated that the pore size decreased and the pore number increased with the increase of SDBS amount, and the morphology of the posttreated latex particles was also significantly influenced by the introducing time of SDBS in the preparation of the original latex particles, and a suitable introducing time was 3 h of polymerization. (c) 2007 Cheng You Kan. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
基金supported by the State Key Laboratory of Chemical Engineering of Zhejiang Universitythe financial support from the National Natural Science Foundation of China (No.20676113).
文摘Poly(styrene-co-glycidyl methacrylate) latex microspheres with uniform size and high-density epoxy groups on the surface were prepared by soap-free emulsion polymerization with batch wise operation mode in the presence of 2.2′- azobis(2-methylpropionamidine) dihydrochloride as an initiator.The kinetics of soap-free emulsion polymerization and the effects of polymerization factors were examined.In addition,the optimum polymerization conditions of poly(styrene-co- glycidyl methacrylate) latex microspheres for...
基金supported by National Natural Science Foundation of China(No.50943028)Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘Submicron-sized peanut-shaped poly（methyl methacrylate）/polystyrene （PMMA/PS） particles were successfully synthesized by seeded soap-free emulsion polymerization of styrene on the spherical crosslinked PMMA seed particles. The obtained peanut- shaped particles showed a novel internal morphology： PS phase formed one domain which linked to the other domain having PMMA core encased by PS shell.
基金financially supported by the National Natural Science Foundation of China (No. 21674059)
文摘Polymerization-induced self-assembly(PISA) is an efficient and versatile method to afford polymeric nano-objects with polymorphic morphologies. Compared to dispersion PISA syntheses based on soluble monomers, the vast majority of emulsion PISA formulations using insoluble monomers leads to kinetically-trapped spheres. Herein, we present aqueous emulsion PISA formulations generating worms and vesicles besides spheres. Two monomers with different butyl groups, n-butyl(n BHMA) and tert-butyl(t BHMA) α-hydroxymethyl acrylate, and thus possessing different water solubilities were synthesized via Baylis-Hillman reaction. Photoinitiated aqueous emulsion polymerizations of n BHMA and t BHMA employing poly(ethylene glycol) macromolecular chain transfer agents(macro-CTAs, PEG45-CTA, and PEG113-CTA) at 40 °C were systematically investigated to evaluate the effect of monomer structure and solubility on the morphology of the generated block copolymer nano-objects. Higher order morphologies including worms and vesicles were readily accessed for t BHMA, which has a higher water solubility than that of n BHMA. This study proves that plasticization of the core-forming block by water plays a key role in enhancing chain mobility required for morphological transition in emulsion PISA.
基金support by the National Natural Science Foundation of China(Grant no.21373042)
文摘One of the major challenges associated with fuel cells is the design of highly efficient electrocatalysts to reduce the high overpotential of the oxygen reduction reaction (ORR). Here we report Polyaniline (PANI) based micro/nanomaterials with or without transition metals, prepared by the emulsion polymerization and subsequent heat treatment. PANI microspheres with the diameter of about 0.7 mu m have been prepared in basic (NH3 solution) condition, using two different types of surfactant (CTAB, SDS) as the stabilizer, ammonium persulphate (APS) as oxidant with aniline/surfactants molar ratio at 1/1 under the hydrothermal treatment. PANI nanorods, Fe-PANI, and Fe-Co-PANI have been synthesized in acidic (HCI) medium with aniline/surfactants molar ratio at 1/2 and polymerization carried out without stirring for 24 h. Products mainly Fe-Co-PANI have shown high current density with increasing sweep rate and excellent specific capacitance 1753 F/g at the scan rate of 1 mV/s. Additionally, it has shown high thermal stability by thermogravimetric analysis (TGA). Fe-PANI has been investigated for excellent performance toward ORR with four electron selectivity in the basic electrolyte. The PANI-based catalysts from emulsion polymerization demonstrate that the method is valuable for making non-precious metal heterogeneous electrocatalysts for ORR or energy storage and conversion technology. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
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).
