In this study,a pair of dicarboxylic acids as cis-trans isomerism—citraconic acid(CA)and mesaconic acid(MA),was incorporated into polymeric networks of poly(N-isopropylacrylamide)(PNIPAM)-based core-shell microgels v...In this study,a pair of dicarboxylic acids as cis-trans isomerism—citraconic acid(CA)and mesaconic acid(MA),was incorporated into polymeric networks of poly(N-isopropylacrylamide)(PNIPAM)-based core-shell microgels via semi-batch precipitation polymerization.We demonstrated that the pH-temperature dual responsiveness of the core-shell microgels is highly correlated with the structure and position of the acid isomers.Both the cis-trans molecular structure and the crosslinking position of the dicarboxylic acids significantly influenced the hydration capacity and surface charge density of the core-shell microgels.These diverse properties first influenced the swelling behavior,further affecting the interfacial behavior of the microgels,including the oil-water dynamic interfacial tension and air-water compression isotherms.Furthermore,the rheological behavior of the microgel suspensions also displayed distinct dependences on the frequency and temperature,illustrating that the cis-trans molecular structure and crosslinked position of the dicarboxylic acids also significantly influenced the interparticle clustering in the bulk solution.Our results suggest that the pH sensitivity of the cis-trans dicarboxylic acid isomer affects the ionization and surface charge distribution of the core or shell layers of individual microgels,which further determines the interparticle interaction and cooperative rearrangement at interfaces and in the bulk.展开更多
Due to the rapid development and potential applications of iron(Ⅲ)-alginate(Fe-Alg)microgels in biomedical as well as environmental engineering,this study explores the preparation and characterization of spherical Fe...Due to the rapid development and potential applications of iron(Ⅲ)-alginate(Fe-Alg)microgels in biomedical as well as environmental engineering,this study explores the preparation and characterization of spherical Fe-Alg microgels using droplet microfluidics combined with an external ionic crosslinking method.This study focused on the role of Fe^(3+)and examined its effects on the physical/chemical properties of microgels under different ionic conditions and reduced or oxidized states.The pH-dependent release behavior of Fe^(3+)from these microgels demonstrates their potential biomedical and environmental applications.Furthermore,the microgels can exhibit magnetism simply by utilizing in situ oxidation,which can be further used for targeted drug delivery and magnetic separation technologies.展开更多
Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques desig...Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.展开更多
Microgels prepared from natural or synthetic hydrogel materials have aroused extensive attention as multifunctional cells or drug carriers,that are promising for tissue engineering and regenerative medicine.Microgels ...Microgels prepared from natural or synthetic hydrogel materials have aroused extensive attention as multifunctional cells or drug carriers,that are promising for tissue engineering and regenerative medicine.Microgels can also be aggregated into microporous scaffolds,promoting cell infiltration and proliferation for tissue repair.This review gives an overview of recent developments in the fabrication techniques and applications of microgels.A series of conventional and novel strategies including emulsification,microfluidic,lithography,electrospray,centrifugation,gas-shearing,three-dimensional bioprinting,etc.are discussed in depth.The characteristics and applications of microgels and microgel-based scaffolds for cell culture and delivery are elaborated with an emphasis on the advantages of these carriers in cell therapy.Additionally,we expound on the ongoing and foreseeable applications and current limitations of microgels and their aggregate in the field of biomedical engineering.Through stimulating innovative ideas,the present review paves new avenues for expanding the application of microgels in cell delivery techniques.展开更多
Photonic materials,which react to light,have garnered interest due to their capability to exhibit adjustable structural colors.Typically,light targets the UV,visible,or near-IR spectrums.In this study,microgel-based p...Photonic materials,which react to light,have garnered interest due to their capability to exhibit adjustable structural colors.Typically,light targets the UV,visible,or near-IR spectrums.In this study,microgel-based photonic materials that are capable of reversibly responding to Xrays have been engineered.To accomplish this,azobenzene(Azo)-containing poly(N-isopropylacrylamide)(pNiPAm)-based microgels are synthesized.Subsequently,ZnS scintillator and Cr/Au are applied on each side of the poly(methyl methacrylate(PMMA)substrate.Subsequently,the Azo MG monolayer is deposited onto the Au surface,followed by the deposition of an additional layer of Cr/Au.This process generates ZnS/PMMA/Cr/Au/Azo MG/Cr/Au or ZnS/Au-Azo MG-Au structure.Functioning as a typical interferometer,ZnS/Au-Azo MG-Au demonstrates tunable colors based on the separation distance between the two Au layers.The ZnS scintillator can absorb and convert X-rays into Uv light,initiating the transition of the Azo groups from a trans to a cis state.Consequently,this transition causes the Azo MG to swell.As Azo MG swells,the distance between the two Au layers increases,resulting in a red-shift of approximately 350 nm in the optical signal of the ZnS/Au-Azo MG-Au interferometer.Remarkably,this X-ray responsivity of the interferometer is reversible,as it returns to its initial state after being stored in the dark for 24 h.To demonstrate its capabilities,the ZnS/Au-Azo MG-Au interferometer successfully releases a drug when triggered by X-ray stimulation,thus validating its potential.The microgel-based interferometers hold significant promise for applications in chemoradiotherapy,radiobiology,and actuators in space.展开更多
Manganese oxide hollow spheres were prepared by a novel and facile approach using pH- responsive microgels as templates. The final products were thoroughly characterized with X-ray powder diffraction, thermogravimetri...Manganese oxide hollow spheres were prepared by a novel and facile approach using pH- responsive microgels as templates. The final products were thoroughly characterized with X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared, and transmission electron microscopy. The results reveal that the shell thickness of manganese oxide hollow spheres increased with the dosage of KMnO4, which implies that a controllable and feasible strategy for manganese oxide hollow spheres prepa- ration has been established. Further studies on the microgels template showed some of them had an irreversible swelling/deswelling transition due to the uneven cross-link extent. Based on the results, a probable formation mechanism for the hollow spheres was proposed.展开更多
MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based o...MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.展开更多
Injecting CO_(2)into the underground for oil displacement and shortage is an important technique for carbon capture,utilization and storage(CCUS).One of the main problems during the CO_(2)injection is the channeling p...Injecting CO_(2)into the underground for oil displacement and shortage is an important technique for carbon capture,utilization and storage(CCUS).One of the main problems during the CO_(2)injection is the channeling plugging.Finding an effective method for the gas channeling plugging is a critical issue in the CO_(2)EOR process.In this work,an acid-resistance microgel named dispersed particle gel(DPG)was characterized and its stability was tested in the CO_(2)environment.The microgel size selection strategies for the homogeneous and heterogeneous reservoirs were respectively investigated using the single core flooding and three parallel core flooding experiments.Moreover,the comparison of microgel alternate CO_(2)(MAC)injection and water alternate CO_(2)(WAC)injection in the dual core flooding experiments were presented for the investigation of the role of microgel on the conformance control in CO_(2)flooding process.The results have shown that the microgel featured with ANH and CAN groups can keep its morphology after aging 7 days in the CO_(2)environment.Where,the small microgel with unobstructed migration and large microgel with good plugging efficiency for the high permeability zone were respectively featured with the higher recovery factor in homogeneous and heterogeneous conditions,which indicate they are preferred used for the oil displacement and conformance control.Compared to WAC injection,MAC injection had a higher incremental recovery factor of 12.4%.It suggests the acid-resistance microgel would be a good candidate for the conformance control during CO_(2)flooding process.展开更多
Microgels with a thermo-sensitive poly(N-isopropylacrylamide)(polyNIPAm) backbone and bis-imidazolium(VIM) ionic cross-links, denoted as poly(NIPAm-co-VIM), were successfully prepared. The as-synthesized ionic microge...Microgels with a thermo-sensitive poly(N-isopropylacrylamide)(polyNIPAm) backbone and bis-imidazolium(VIM) ionic cross-links, denoted as poly(NIPAm-co-VIM), were successfully prepared. The as-synthesized ionic microgels were converted to nanoreactors, denoted as Au@PNI MGs, upon generation and immobilization of gold nanoparticles(Au NPs) of 5–8 nm in size into poly(NIPAm-co-VIM). The content of Au NPs in microgels could be regulated by controlling the 1,6-dibromohexane/vinylimidazole molar ratio in the quaternization reaction. The microgel-based nanoreactors were morphologically spherical and uniform in size, and presented reversible thermo-sensitive behavior with volume phase transition temperatures(VPTTs) at 39–40 °C. The Au@PNI MGs were used for the reduction of 4-nitrophenol, of which the catalytic activity could be modulated by temperature.展开更多
A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPA...A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPAM） microgels were first synthesized by seed precipitation polymerization using colloidal Si O2 nanoparticles as seeds, followed by removing the silica cores of the formed Si O2/PNIPAM core/shell composite microgels with hydrofluoric acid. Then, the discontinuously hollow hydrogel microfibers were produced by unidirectional freezing of 1 wt% hollow PNIPAM microgel aqueous dispersion in liquid nitrogen bath, followed by freeze-drying to remove the formed ice crystals. Many orderly arrayed dents were observed on the surfaces of the hydrogel microfibers by field-emission scanning electron microscopy, indicating that they are constructed by closely packed monodisperse hollow PNIPAM microgels. The effect of freezing method and the hollow microgel concentration in the aqueous dispersion on the morphological structure of the hollow hydrogel microfibers was investigated.展开更多
Three-dimensional(3D)bioprinting is a powerful approach that enables the fabrication of 3D tissue constructs that retain complex biological functions.However,the dense hydrogel networks that form after the gelation of...Three-dimensional(3D)bioprinting is a powerful approach that enables the fabrication of 3D tissue constructs that retain complex biological functions.However,the dense hydrogel networks that form after the gelation of bioinks often restrict the migration and proliferation of encapsulated cells.Herein,a sacrificial microgel-laden bioink strategy was designed for directly bioprinting constructs with mesoscale pore networks(MPNs)for enhancing nutrient delivery and cell growth.The sacrificial microgel-laden bioink,which contains cell/gelatin methacryloyl(GelMA)mixture and gelled gelatin microgel,is first thermo-crosslinked to fabricate temporary predesigned cell-laden constructs by extrusion bioprinting onto a cold platform.Then,the construct is permanently stabilized through photo-crosslinking of GelMA.The MPNs inside the printed constructs are formed after subsequent dissolution of the gelatin microgel.These MPNs allowed for effective oxygen/nutrient diffusion,facilitating the generation of bioactive tissues.Specifically,osteoblast and human umbilical vein endothelial cells encapsulated in the bioprinted large-scale constructs(≥1 cm)with MPNs showed enhanced bioactivity during culture.The 3D bioprinting strategy based on the sacrificial microgel-laden bioink provided a facile method to facilitate formation of complex tissue constructs with MPNs and set a foundation for future optimization of MPN-based tissue constructs with applications in diverse areas of tissue engineering.展开更多
The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM ...The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM microgel)by seed-precipitation polymerization method using butenoic acid modified Au @ Ag NRs as seeds. When the temperature of the aqueous medium increases from 20℃ to 50℃,the localized surface plasmon resonance( LSPR) band of the entrapped Au @ Ag NR is pronouncedly red-shifted because of the decreased spatial distances between them as a result of shrinkage of the microgels,leading to their plasmonic coupling. The temperature tunable plasmonic coupling is demonstrated by temperature dependence of the surface enhanced Raman spectroscopy( SERS) signal of 1-naphthol in aqueous solution. Different from static plasmonic coupling modes from nanostructured assembly or array system of noble metals,the proposed plasmonic coupling can be dynamically controlled by environmental temperature. Therefore, the thermo responsive hybrid microgels have potential applications in mobile LSPR or SERS microsensors for living tissues or cells.展开更多
The novel microgels, poly[di（ethylene glycol） methyl ether methacrylate-co-2-methoxyethyl acrylate] poly（DEGMMA-co-MEA） microgels, were synthesized. The poly（DEGMMA-co-MEA） microgels were thermo-sensitive and ex...The novel microgels, poly[di（ethylene glycol） methyl ether methacrylate-co-2-methoxyethyl acrylate] poly（DEGMMA-co-MEA） microgels, were synthesized. The poly（DEGMMA-co-MEA） microgels were thermo-sensitive and exhibited a volume phase transitive temperature（VPTT） of 14–22 ℃. The incorporation of hydrophobic comonomer MEA shifted the VPTT of poly（DEGMMA-co-MEA） microgels to lower temperatures. The interfacial interaction of poly（DEGMMA-co-MEA） microgels and three model proteins, namely fibrinogen, bovine serum albumin and lysozyme, was investigated by quartz crystal microbalance（QCM）. An injection sequence of ＂microgel-after-protein＂ was then established for the real-time study of the interaction of proteins and the microgels at their swollen and collapsed states by using QCM technique. The results indicated that the interfacial interaction of poly（DEGMMA-co-MEA） microgels and adsorbed protein layers was mainly determined by the electrostatic interaction. Because poly（DEGMMA-co-MEA） microgels were negatively charged in Tris-HCl buffer solution（pH = 7.4）, the microgels did not adsorb on negatively charged fibrinogen and bovine serum albumin layers but strongly adsorbed on positively charged lysozyme layer. Stronger interaction between lysozyme and the microgels at collapsed state（i.e. at 37 ℃） was observed. Furthermore, the incorporation of MEA might weaken the interaction between poly（DEGMMA-co-MEA） microgels and proteins.展开更多
The research and application of responsive materials have long been hampered by their complicated designs and tedious construction processes.Besides,many current responsive materials show retard or weak responsiveness...The research and application of responsive materials have long been hampered by their complicated designs and tedious construction processes.Besides,many current responsive materials show retard or weak responsiveness.In this study,responsive hybrid poly(vinyl alcohol)hydrogel membranes with embedded poly(N-isopropylacrylamide-acrylic acid)microgels as valves were constructed by simple mixing and subsequent freezing-thawing process.In the structure of the membranes,the matrix poly(vinyl alcohol)chains thread through and entangle with the microgels,and the microgels are firmly constrained within the hybrid hydrogel network.The fast and sharp temperature responsiveness of the embedded microgels was largely retained and endowed the hydrogel membrane with excellent temperature and pH responsiveness.Moreover,the hydrogel membrane showed excellent fatigue resistance in both temperature and pH-responsive flux examination.This study presented the great potential of these hybrid hydrogel membranes in biomedical applications and provided a new strategy for the future design and construction of responsive biomaterials.展开更多
Adopting N, N＇-methylene-bis （aculamide） （MBA） and inorganic clay （hectorite） as chemical and physical crosslinking agent, respectively, a series temperature sensitive microgels, based on N-isopropylacrylamide ...Adopting N, N＇-methylene-bis （aculamide） （MBA） and inorganic clay （hectorite） as chemical and physical crosslinking agent, respectively, a series temperature sensitive microgels, based on N-isopropylacrylamide （NIPAM） as a main monomer and tert-butyl acrylate （tBA） as a comonomer were synthesized by surfactant-free emulsion polymerization （SFEP）. The microgel particle size and morphology was investigated by means of Atomic Force Microscope （AFM）. The surface tension of latex particles was measured by OCA 40 Micro Video based contact angle measuring device. The results showed that the particle size of the microgels with clay as cross-linker was smaller than that using MBA as chemical cross-linker, but exterior morphology of physical microgels is not as clean and neat as chemical microgels. In general, surface tension decreases with increasing hydrophobic tBA content. These smart microgels varied with tetnperature have the potential applications in the field of drug delivery and intelligent gel fiber.展开更多
Droplet based microfluidic is an effective, versatile and scalable approach which can be used to produce structured microgels with desirable features. The high degree of control endowed with microfluidics enables the ...Droplet based microfluidic is an effective, versatile and scalable approach which can be used to produce structured microgels with desirable features. The high degree of control endowed with microfluidics enables the formation of various functional microgels such as multicompartment encapsulations, Janus shaped particles and non spherical microgels. These microgels have aroused great interest in biological engineering aspect, since they outperform their counterparts produced from other techniques and have been applied in drug delivery, 3 Dimensional cell culture, micro tissues, single cell assay, tissue engineering and bioimaging. In this review, we will summarize the fabrication processes, technology comparisons and the usages in biomedical applications.展开更多
The non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends was investigated by differential scanning calorimetry(DSC). The Mo equation was employed to analyze the non-isothermal crystallization da...The non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends was investigated by differential scanning calorimetry(DSC). The Mo equation was employed to analyze the non-isothermal crystallization data. The crystallization activation energies were also evaluated by the Kissinger method. The results show that the crystallization onset temperature(T onset) and crystallization peak temperature(T p) decrease with the increase of the content of reactive microgel, while ΔT(T onset–T p), the crystallization half-time(t1/2) and the crystallization enthalpy(ΔH c) increase. The required cooling rates of blends are higher than that of neat nylon6 in order to achieve the same relative crystallinity in a unit of time. The crystallization activation energies of the reactive microgel/nylon 6 blends are greater than those of the neat nylon 6. When the content of reactive microgel is 30%, the relative crystallinity(X t) reaches the maximum.展开更多
The curing of a microgel-epoxy resin two phase polymer prepared by in situ copolymerization of unsaturated polyester with acrylic monomer was studied. The unsaturated unit reacted with N—H during the cure of the resi...The curing of a microgel-epoxy resin two phase polymer prepared by in situ copolymerization of unsaturated polyester with acrylic monomer was studied. The unsaturated unit reacted with N—H during the cure of the resin with ethylene diamine. The Michael type reaction was ten times more rapid than the addition of N—H to epoxide.This was accounted for the lower apparent activation energy of the curing of the two phase resin.展开更多
In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In th...In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.展开更多
Reactive acrylate microgels with different reactive groups such as carboxyl, hydroxide groups had excellent properties such as quick-dry, low viscosity, high adhesion and hardness, which made them extensively used in ...Reactive acrylate microgels with different reactive groups such as carboxyl, hydroxide groups had excellent properties such as quick-dry, low viscosity, high adhesion and hardness, which made them extensively used in preparing paints or in coating-modification. Reactive acrylate microgels were prepared by emulsion co-polymerization with zwitterions surfactant, anionic surfactant and nonionic surfactant as co-emulsifier. The water-base baking paints made from reactive acrylate microgels and melamine-formaldehyde resin had excellent combination properties. The aluminium powder can be well-dispersed in the paints. The influences of monomer components on the properties of the water-base baking paints were discussed in this paper. And the baking paints were also compared with the marketing solvent acrylate baking paints. It was found that the water-base acrylate amino baking paints had better combination properties than the organic solvent acrylate baking paints, which means that the water-base baking paints had a bright marketing future.展开更多
基金financially supported by the National Natural Science Foundation of China(No.22303033)the Fundamental Research Funds for the Central Universities,China(No.JUSRP123017)+1 种基金Wuxi“Taihu Light”Science and Technology Project-Basic Research(No.K20231063)the Research Matching Grant Scheme at CUHK(No.8601309)。
文摘In this study,a pair of dicarboxylic acids as cis-trans isomerism—citraconic acid(CA)and mesaconic acid(MA),was incorporated into polymeric networks of poly(N-isopropylacrylamide)(PNIPAM)-based core-shell microgels via semi-batch precipitation polymerization.We demonstrated that the pH-temperature dual responsiveness of the core-shell microgels is highly correlated with the structure and position of the acid isomers.Both the cis-trans molecular structure and the crosslinking position of the dicarboxylic acids significantly influenced the hydration capacity and surface charge density of the core-shell microgels.These diverse properties first influenced the swelling behavior,further affecting the interfacial behavior of the microgels,including the oil-water dynamic interfacial tension and air-water compression isotherms.Furthermore,the rheological behavior of the microgel suspensions also displayed distinct dependences on the frequency and temperature,illustrating that the cis-trans molecular structure and crosslinked position of the dicarboxylic acids also significantly influenced the interparticle clustering in the bulk solution.Our results suggest that the pH sensitivity of the cis-trans dicarboxylic acid isomer affects the ionization and surface charge distribution of the core or shell layers of individual microgels,which further determines the interparticle interaction and cooperative rearrangement at interfaces and in the bulk.
基金financially supported by the Fundamental Research Funds for the Central Universities(No.KVJBMC23001536)Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing(No.20240518)+2 种基金the State Key Laboratory of Molecular Engineering of Polymers(Fudan University)(No.K2024-15)the Central Universities support from Beijing Jiaotong University(No.KVYJS24011536)the National Natural Science Foundation of China(No.62175012).
文摘Due to the rapid development and potential applications of iron(Ⅲ)-alginate(Fe-Alg)microgels in biomedical as well as environmental engineering,this study explores the preparation and characterization of spherical Fe-Alg microgels using droplet microfluidics combined with an external ionic crosslinking method.This study focused on the role of Fe^(3+)and examined its effects on the physical/chemical properties of microgels under different ionic conditions and reduced or oxidized states.The pH-dependent release behavior of Fe^(3+)from these microgels demonstrates their potential biomedical and environmental applications.Furthermore,the microgels can exhibit magnetism simply by utilizing in situ oxidation,which can be further used for targeted drug delivery and magnetic separation technologies.
基金supported by the National Natural Science Foundation project“Micro-Scale Effect of Oil-Gas Flow and the Mechanism of Enhancing Shale Oil Recovery by Natural Gas Injection”(No.52074317)。
文摘Oilfields worldwide are increasingly grappling with challenges such as early water breakthrough and high water production,yet direct,targeted solutions remain elusive.In recent years,chemical flooding techniques designed for tertiary oil recovery have garnered significant attention,with microgel flooding emerging as a particularly prominent area of research.Despite its promise,the complex mechanisms underlying microgel flooding have been rarely investigated numerically.This study aims to address these gaps by characterizing the distribution of microgel concentration and viscosity within different pore structures.To enhance the accuracy of these characterizations,the viscosity of microgels is adjusted to account for the shear effects induced by flow rate and the swelling effects driven by salinity variations.The absolute permeability of the rock and the relative permeability of both oil and microgel are also analyzed to elucidate the mechanisms of microgel flooding.Additionally,a connectivity model is employed to achieve a quantitative representation of fluid flow capacity.The proposed model is validated through conceptual examples and applied to real oilfield blocks,demonstrating its accuracy and practical applicability.
基金supported by the National Key Research and Development Program of China(No.2022YFA1104600)the National Natural Science Foundation of China(NSFC)Program(Nos.32201183,31927801,32101105)the Science and Technology Program of Guangzhou(SL2022A04J00774).
文摘Microgels prepared from natural or synthetic hydrogel materials have aroused extensive attention as multifunctional cells or drug carriers,that are promising for tissue engineering and regenerative medicine.Microgels can also be aggregated into microporous scaffolds,promoting cell infiltration and proliferation for tissue repair.This review gives an overview of recent developments in the fabrication techniques and applications of microgels.A series of conventional and novel strategies including emulsification,microfluidic,lithography,electrospray,centrifugation,gas-shearing,three-dimensional bioprinting,etc.are discussed in depth.The characteristics and applications of microgels and microgel-based scaffolds for cell culture and delivery are elaborated with an emphasis on the advantages of these carriers in cell therapy.Additionally,we expound on the ongoing and foreseeable applications and current limitations of microgels and their aggregate in the field of biomedical engineering.Through stimulating innovative ideas,the present review paves new avenues for expanding the application of microgels in cell delivery techniques.
基金supported by Natural Science Foundation of Jiangsu Province(No.BK20221359)Interdisciplinary Basic Frontier Innovation Program of Suzhou Medical College of Soochow University,State Key Laboratory of Radiation Medicine and Protection(No.GZC00501)+1 种基金the National Natural Science Foundation of China(No.51873137)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Photonic materials,which react to light,have garnered interest due to their capability to exhibit adjustable structural colors.Typically,light targets the UV,visible,or near-IR spectrums.In this study,microgel-based photonic materials that are capable of reversibly responding to Xrays have been engineered.To accomplish this,azobenzene(Azo)-containing poly(N-isopropylacrylamide)(pNiPAm)-based microgels are synthesized.Subsequently,ZnS scintillator and Cr/Au are applied on each side of the poly(methyl methacrylate(PMMA)substrate.Subsequently,the Azo MG monolayer is deposited onto the Au surface,followed by the deposition of an additional layer of Cr/Au.This process generates ZnS/PMMA/Cr/Au/Azo MG/Cr/Au or ZnS/Au-Azo MG-Au structure.Functioning as a typical interferometer,ZnS/Au-Azo MG-Au demonstrates tunable colors based on the separation distance between the two Au layers.The ZnS scintillator can absorb and convert X-rays into Uv light,initiating the transition of the Azo groups from a trans to a cis state.Consequently,this transition causes the Azo MG to swell.As Azo MG swells,the distance between the two Au layers increases,resulting in a red-shift of approximately 350 nm in the optical signal of the ZnS/Au-Azo MG-Au interferometer.Remarkably,this X-ray responsivity of the interferometer is reversible,as it returns to its initial state after being stored in the dark for 24 h.To demonstrate its capabilities,the ZnS/Au-Azo MG-Au interferometer successfully releases a drug when triggered by X-ray stimulation,thus validating its potential.The microgel-based interferometers hold significant promise for applications in chemoradiotherapy,radiobiology,and actuators in space.
文摘Manganese oxide hollow spheres were prepared by a novel and facile approach using pH- responsive microgels as templates. The final products were thoroughly characterized with X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, Fourier transform infrared, and transmission electron microscopy. The results reveal that the shell thickness of manganese oxide hollow spheres increased with the dosage of KMnO4, which implies that a controllable and feasible strategy for manganese oxide hollow spheres prepa- ration has been established. Further studies on the microgels template showed some of them had an irreversible swelling/deswelling transition due to the uneven cross-link extent. Based on the results, a probable formation mechanism for the hollow spheres was proposed.
基金financially supported by the National Natural Science Foundation of China(No.52002354)China Postdoctoral Science Foundation(No.2020M672256)。
文摘MXene nanomaterials are one of the most promising electrode material candidates for supercapacitors owing to their high conductivity,abundant surface functional groups and large surface area.However,electrodes based on MXene may result in low ion-accessible surface area and blocked ion transport pathways because of the self-restacking of MXene nanosheets.It is essential to suppress the self-res tacking of nanosheets and increase the electrochemical active sites in order to optimize the electrode.In this work,bidirectionally aligned MXene hybrid aerogel(A-MHA)assembled with MXene nanosheets and microgels is prepared using a facile bidirectional freeze casting and freeze-drying method.The bidirectionally aligned structure together with the three-dimensional structured microgels in the A-MHAs,can improve the ionaccessible surface area and provide more barrier-free channels by exposing more active sites and ensuring electrolyte transport freely.The A-MHA with MXene microgels content of 40 wt%exhibits a high specific capacitance of 760 F·g^(-1)at 1 A·g^(-1)and a remarkable cyclic performance of 97%after 10,000 cycles at100 mV·s^(-1)in 1 mol·L^(-1)H_(2)SO_(4)electrolyte.A-MHAs show remarkable electrochemical properties and are of potential application in energy storage.
基金supported by the National Natural Science Foundation of China(52004305)the Postdoctoral Research Foundation of China(2021M693497)the Science Foundation of China University of Petroleum,Beijing(2462020XKBH006)。
文摘Injecting CO_(2)into the underground for oil displacement and shortage is an important technique for carbon capture,utilization and storage(CCUS).One of the main problems during the CO_(2)injection is the channeling plugging.Finding an effective method for the gas channeling plugging is a critical issue in the CO_(2)EOR process.In this work,an acid-resistance microgel named dispersed particle gel(DPG)was characterized and its stability was tested in the CO_(2)environment.The microgel size selection strategies for the homogeneous and heterogeneous reservoirs were respectively investigated using the single core flooding and three parallel core flooding experiments.Moreover,the comparison of microgel alternate CO_(2)(MAC)injection and water alternate CO_(2)(WAC)injection in the dual core flooding experiments were presented for the investigation of the role of microgel on the conformance control in CO_(2)flooding process.The results have shown that the microgel featured with ANH and CAN groups can keep its morphology after aging 7 days in the CO_(2)environment.Where,the small microgel with unobstructed migration and large microgel with good plugging efficiency for the high permeability zone were respectively featured with the higher recovery factor in homogeneous and heterogeneous conditions,which indicate they are preferred used for the oil displacement and conformance control.Compared to WAC injection,MAC injection had a higher incremental recovery factor of 12.4%.It suggests the acid-resistance microgel would be a good candidate for the conformance control during CO_(2)flooding process.
基金the National Natural Science Foundation of China(No.21704092)Science Foundation of Zhejiang SciTech University(No.16062194-Y)for financial support
文摘Microgels with a thermo-sensitive poly(N-isopropylacrylamide)(polyNIPAm) backbone and bis-imidazolium(VIM) ionic cross-links, denoted as poly(NIPAm-co-VIM), were successfully prepared. The as-synthesized ionic microgels were converted to nanoreactors, denoted as Au@PNI MGs, upon generation and immobilization of gold nanoparticles(Au NPs) of 5–8 nm in size into poly(NIPAm-co-VIM). The content of Au NPs in microgels could be regulated by controlling the 1,6-dibromohexane/vinylimidazole molar ratio in the quaternization reaction. The microgel-based nanoreactors were morphologically spherical and uniform in size, and presented reversible thermo-sensitive behavior with volume phase transition temperatures(VPTTs) at 39–40 °C. The Au@PNI MGs were used for the reduction of 4-nitrophenol, of which the catalytic activity could be modulated by temperature.
基金supported by the National Natural Science Foundation of China(Nos.51073033 and 51373030)the Fundamental Research Funds for the Central Universities(No.2232014D3-43)
文摘A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPAM） microgels were first synthesized by seed precipitation polymerization using colloidal Si O2 nanoparticles as seeds, followed by removing the silica cores of the formed Si O2/PNIPAM core/shell composite microgels with hydrofluoric acid. Then, the discontinuously hollow hydrogel microfibers were produced by unidirectional freezing of 1 wt% hollow PNIPAM microgel aqueous dispersion in liquid nitrogen bath, followed by freeze-drying to remove the formed ice crystals. Many orderly arrayed dents were observed on the surfaces of the hydrogel microfibers by field-emission scanning electron microscopy, indicating that they are constructed by closely packed monodisperse hollow PNIPAM microgels. The effect of freezing method and the hollow microgel concentration in the aqueous dispersion on the morphological structure of the hollow hydrogel microfibers was investigated.
基金sponsored by the National Nature Science Foundation of China(Nos.U1609207,81827804).
文摘Three-dimensional(3D)bioprinting is a powerful approach that enables the fabrication of 3D tissue constructs that retain complex biological functions.However,the dense hydrogel networks that form after the gelation of bioinks often restrict the migration and proliferation of encapsulated cells.Herein,a sacrificial microgel-laden bioink strategy was designed for directly bioprinting constructs with mesoscale pore networks(MPNs)for enhancing nutrient delivery and cell growth.The sacrificial microgel-laden bioink,which contains cell/gelatin methacryloyl(GelMA)mixture and gelled gelatin microgel,is first thermo-crosslinked to fabricate temporary predesigned cell-laden constructs by extrusion bioprinting onto a cold platform.Then,the construct is permanently stabilized through photo-crosslinking of GelMA.The MPNs inside the printed constructs are formed after subsequent dissolution of the gelatin microgel.These MPNs allowed for effective oxygen/nutrient diffusion,facilitating the generation of bioactive tissues.Specifically,osteoblast and human umbilical vein endothelial cells encapsulated in the bioprinted large-scale constructs(≥1 cm)with MPNs showed enhanced bioactivity during culture.The 3D bioprinting strategy based on the sacrificial microgel-laden bioink provided a facile method to facilitate formation of complex tissue constructs with MPNs and set a foundation for future optimization of MPN-based tissue constructs with applications in diverse areas of tissue engineering.
基金National Natural Science Foundation of China(No.51373030)Chinese Universities Scientific Fund(No.CUSF-DH-D-2014023)
文摘The monodisperse Au@Ag bimetallic nanorod is encapsulated by crosslinked poly( N-isopropylacrylamide)( PNIPAM) to produce thermo-responsive composite microgel with well-defined core-shell structure( Au@ Ag NR@ PNIPAM microgel)by seed-precipitation polymerization method using butenoic acid modified Au @ Ag NRs as seeds. When the temperature of the aqueous medium increases from 20℃ to 50℃,the localized surface plasmon resonance( LSPR) band of the entrapped Au @ Ag NR is pronouncedly red-shifted because of the decreased spatial distances between them as a result of shrinkage of the microgels,leading to their plasmonic coupling. The temperature tunable plasmonic coupling is demonstrated by temperature dependence of the surface enhanced Raman spectroscopy( SERS) signal of 1-naphthol in aqueous solution. Different from static plasmonic coupling modes from nanostructured assembly or array system of noble metals,the proposed plasmonic coupling can be dynamically controlled by environmental temperature. Therefore, the thermo responsive hybrid microgels have potential applications in mobile LSPR or SERS microsensors for living tissues or cells.
基金financially supported by the National Natural Science Foundation of China(Nos.21274129 and 21322406)the Fundamental Research Funds for the Central Universities(No.2014XZZX003-21)+2 种基金the third level of 2013 Zhejiang Province 151 Talent ProjectOpen Research Fund of State Key Laboratory of Polymer Physics and ChemistryChangchun Institute of Applied Chemistry,Chinese Academy of Sciences
文摘The novel microgels, poly[di（ethylene glycol） methyl ether methacrylate-co-2-methoxyethyl acrylate] poly（DEGMMA-co-MEA） microgels, were synthesized. The poly（DEGMMA-co-MEA） microgels were thermo-sensitive and exhibited a volume phase transitive temperature（VPTT） of 14–22 ℃. The incorporation of hydrophobic comonomer MEA shifted the VPTT of poly（DEGMMA-co-MEA） microgels to lower temperatures. The interfacial interaction of poly（DEGMMA-co-MEA） microgels and three model proteins, namely fibrinogen, bovine serum albumin and lysozyme, was investigated by quartz crystal microbalance（QCM）. An injection sequence of ＂microgel-after-protein＂ was then established for the real-time study of the interaction of proteins and the microgels at their swollen and collapsed states by using QCM technique. The results indicated that the interfacial interaction of poly（DEGMMA-co-MEA） microgels and adsorbed protein layers was mainly determined by the electrostatic interaction. Because poly（DEGMMA-co-MEA） microgels were negatively charged in Tris-HCl buffer solution（pH = 7.4）, the microgels did not adsorb on negatively charged fibrinogen and bovine serum albumin layers but strongly adsorbed on positively charged lysozyme layer. Stronger interaction between lysozyme and the microgels at collapsed state（i.e. at 37 ℃） was observed. Furthermore, the incorporation of MEA might weaken the interaction between poly（DEGMMA-co-MEA） microgels and proteins.
基金supported by the National Natural Science Foundation of China(Nos.22275137 and 82202342)Natural Science Foundation of Tianjin Municipal Science and Technology Commission(No.21JCYBJC01810).
文摘The research and application of responsive materials have long been hampered by their complicated designs and tedious construction processes.Besides,many current responsive materials show retard or weak responsiveness.In this study,responsive hybrid poly(vinyl alcohol)hydrogel membranes with embedded poly(N-isopropylacrylamide-acrylic acid)microgels as valves were constructed by simple mixing and subsequent freezing-thawing process.In the structure of the membranes,the matrix poly(vinyl alcohol)chains thread through and entangle with the microgels,and the microgels are firmly constrained within the hybrid hydrogel network.The fast and sharp temperature responsiveness of the embedded microgels was largely retained and endowed the hydrogel membrane with excellent temperature and pH responsiveness.Moreover,the hydrogel membrane showed excellent fatigue resistance in both temperature and pH-responsive flux examination.This study presented the great potential of these hybrid hydrogel membranes in biomedical applications and provided a new strategy for the future design and construction of responsive biomaterials.
基金Supported by the Major Project of Science and Technology Research of the Educational Ministry of China (No.105077) and DoctorateInnovation Foundation of Donghua University(No.106 06 001900611)
文摘Adopting N, N＇-methylene-bis （aculamide） （MBA） and inorganic clay （hectorite） as chemical and physical crosslinking agent, respectively, a series temperature sensitive microgels, based on N-isopropylacrylamide （NIPAM） as a main monomer and tert-butyl acrylate （tBA） as a comonomer were synthesized by surfactant-free emulsion polymerization （SFEP）. The microgel particle size and morphology was investigated by means of Atomic Force Microscope （AFM）. The surface tension of latex particles was measured by OCA 40 Micro Video based contact angle measuring device. The results showed that the particle size of the microgels with clay as cross-linker was smaller than that using MBA as chemical cross-linker, but exterior morphology of physical microgels is not as clean and neat as chemical microgels. In general, surface tension decreases with increasing hydrophobic tBA content. These smart microgels varied with tetnperature have the potential applications in the field of drug delivery and intelligent gel fiber.
文摘Droplet based microfluidic is an effective, versatile and scalable approach which can be used to produce structured microgels with desirable features. The high degree of control endowed with microfluidics enables the formation of various functional microgels such as multicompartment encapsulations, Janus shaped particles and non spherical microgels. These microgels have aroused great interest in biological engineering aspect, since they outperform their counterparts produced from other techniques and have been applied in drug delivery, 3 Dimensional cell culture, micro tissues, single cell assay, tissue engineering and bioimaging. In this review, we will summarize the fabrication processes, technology comparisons and the usages in biomedical applications.
基金Supported by the Graduate Innovative Fund of Wuhan Institute of Technology(CX2013019)
文摘The non-isothermal crystallization kinetics of reactive microgel/nylon 6 blends was investigated by differential scanning calorimetry(DSC). The Mo equation was employed to analyze the non-isothermal crystallization data. The crystallization activation energies were also evaluated by the Kissinger method. The results show that the crystallization onset temperature(T onset) and crystallization peak temperature(T p) decrease with the increase of the content of reactive microgel, while ΔT(T onset–T p), the crystallization half-time(t1/2) and the crystallization enthalpy(ΔH c) increase. The required cooling rates of blends are higher than that of neat nylon6 in order to achieve the same relative crystallinity in a unit of time. The crystallization activation energies of the reactive microgel/nylon 6 blends are greater than those of the neat nylon 6. When the content of reactive microgel is 30%, the relative crystallinity(X t) reaches the maximum.
基金The project is supported by National Natural Science Foundation of China.
文摘The curing of a microgel-epoxy resin two phase polymer prepared by in situ copolymerization of unsaturated polyester with acrylic monomer was studied. The unsaturated unit reacted with N—H during the cure of the resin with ethylene diamine. The Michael type reaction was ten times more rapid than the addition of N—H to epoxide.This was accounted for the lower apparent activation energy of the curing of the two phase resin.
基金This work was supported by the National Natural Science Foundation of China(Nos.90206020 and 29901001).
文摘In the UV-Vis spectra of pure light-scattering systems, there is an exponential relationship between absorbance and wavelength （A = Kλ^-n）. Here, the exponent n is named as flocculation-coagulation parameter. In the present paper, the effects of different additives on the stability of poly（N,N＇-methylenebisacrylamide-co-4-vinylpyridine） （poly（Bis-co-4-VP）） microgel dispersion were studied in detail via this parameter. The results showed that the stability of the dispersion mainly comes from the ionization of pyridine groups, making the microgel positively charged on its surface. This was confirmed by the measurement of Zeta potential and the result of conductometric titration. The result of fluorescence analysis indicated that the hydrophobicity in the microgels is enhanced with the increase in total 4-VP unit content.
基金supported by the Science Foundation of Shanghai Municipal Education Commission (Grant No.03AK59)
文摘Reactive acrylate microgels with different reactive groups such as carboxyl, hydroxide groups had excellent properties such as quick-dry, low viscosity, high adhesion and hardness, which made them extensively used in preparing paints or in coating-modification. Reactive acrylate microgels were prepared by emulsion co-polymerization with zwitterions surfactant, anionic surfactant and nonionic surfactant as co-emulsifier. The water-base baking paints made from reactive acrylate microgels and melamine-formaldehyde resin had excellent combination properties. The aluminium powder can be well-dispersed in the paints. The influences of monomer components on the properties of the water-base baking paints were discussed in this paper. And the baking paints were also compared with the marketing solvent acrylate baking paints. It was found that the water-base acrylate amino baking paints had better combination properties than the organic solvent acrylate baking paints, which means that the water-base baking paints had a bright marketing future.
