The root system actively reacts to mechanical stimuli in its environment,transmitting mechanical signals to optimize the utilization of environmental resources.While the mechanical impedance created by the growth medi...The root system actively reacts to mechanical stimuli in its environment,transmitting mechanical signals to optimize the utilization of environmental resources.While the mechanical impedance created by the growth medium serves as the primary source of stimulation for the roots,extensive research has focused on the roots'response to static mechanical stimulation.However,the impact of dynamic mechanical stimulation on root phenotype remains underexplored.In this study,we utilized a low acyl gellan gum/polyacrylamide(GG/PAM)double network elastic hydrogel as the growth medium for rapeseed.We constructed a mechanical device to investigate the effects of reciprocating extrusion stimulation on the growth of the rapeseed root system.After three weeks of mechanical stimulation,the root system exhibited a significant increase in lateral roots.This branching enhanced the roots'anchoring and penetration into the hydrogel,thereby improving the root system's adaptability to its environment.Our findings offer valuable data and insights into the effects of reciprocating mechanical stimulation on root growth,providing a new way for engineering root phenotype.展开更多
Hydrogels with good antifouling and mechanical properties as well as biocompatibility have great application potential in the field of biomedicine.In this paper,a newly double network(DN)hydrogel was prepared based on...Hydrogels with good antifouling and mechanical properties as well as biocompatibility have great application potential in the field of biomedicine.In this paper,a newly double network(DN)hydrogel was prepared based on zwitterionic material sulfobetaine methacrylate(SBMA)and natural polysaccharide,sodium alginate(SA).The PSBMA network is covalently crosslinked while the SA network is ionically crosslinked by Ca^(2+).The hybrid crosslinked double network structure endows the DN hydrogel with excellent mechanical properties(E=0.19±0.01 MPa,σ=0.73±0.03 MPa),fast self-recovery ability as well as excellent fatigue resistance.Moreover,the results show that the PSBMA/SA-Ca^(2+)DN hydrogel is biocompatible and resists the absorption of non-specific proteins and adhesion of microorganisms,such as cells and algae,exhibiting outstanding antifouling properties.These unique characteristics of PSBMA/SA-Ca^(2+)DN hydrogel make it a promising candidate for biomedical application,such as artificial connective tissues,implantable devices,and underwater equipment.展开更多
Double network(DN)hydrogels as one kind of tough gels have attracted extensive at-tention for their potential applications in biomedical and load-bearing fields.Herein,we import more functions like shape memory into t...Double network(DN)hydrogels as one kind of tough gels have attracted extensive at-tention for their potential applications in biomedical and load-bearing fields.Herein,we import more functions like shape memory into the conventional tough DN hydro-gel system.We synthesize the PEG-PDAC/P(AAm-co-AAc)DN hydrogels,of which the first network is a well-defined PEG(polyethylene glycol)network loaded with PDAC(poly(acryloyloxyethyltrimethyl ammonium chloride))strands,while the second network is formed by copolymerizing AAm(acrylamide)with AAc(acrylic acid)and cross-linker MBAA(N;N′-methylenebisacrylamide).The PEG-PDAC/P(AAm-co-AAc)DN gels exhibits high mechanical strength.The fracture stress and toughness of the DN gels reach up to 0.9 MPa and 3.8 MJ/m^3,respectively.Compared with the conventional double network hydrogels with neutral polymers as the soft and ductile second network,the PEG-PDAC/P(AAm-co-AAc)DN hydrogels use P(AAm-co-AAc),a weak polyelectrolyte,as the second network.The AAc units serve as the coordination points with Fe^3+ions and physically crosslink the second network,which realizes the shape memory property activated by the reducing ability of ascorbic acid.Our results indicate that the high mechanical strength and shape memory properties,probably the two most important characters related to the potential application of the hydrogels,can be introduced simultaneously into the DN hydrogels if the functional monomer has been integrated into the network of DN hydrogels smartly.展开更多
Current animal models of nerve root compression due to lumbar disc herniation only assess the mechanical compression of nerve roots and the inflammatory response. Moreover, the pressure applied in these models is stat...Current animal models of nerve root compression due to lumbar disc herniation only assess the mechanical compression of nerve roots and the inflammatory response. Moreover, the pressure applied in these models is static, meaning that the nerve root cannot be dynamically compressed. This is very different from the pathogenesis of lumbar disc herniation. In this study, a chitosan/polyacrylamide double-network hydrogel was prepared by a simple two-step method. The swelling ratio of the double-network hydrogel increased with prolonged time, reaching 140. The compressive strength and compressive modulus of the hydrogel reached 53.6 and 0.34 MPa, respectively. Scanning electron microscopy revealed the hydrogel's crosslinked structure with many interconnecting pores. An MTT assay demonstrated that the number of viable cells in contact with the hydrogel extracts did not significantly change relative to the control surface. Thus, the hydrogel had good biocompatibility. Finally, the double-network hydrogel was used to compress the L4 nerve root of male sand rats to simulate lumbar disc herniation nerve root compression. The hydrogel remained in its original position after compression, and swelled with increasing time. Edema appeared around the nerve root and disappeared 3 weeks after operation. This chitosan/polyacrylamide double-network hydrogel has potential as a new implant material for animal models of lumbar nerve root compression. All animal experiments were approved by the Animal Ethics Committee of Neurosurgical Institute of Beijing, Capital Medical University, China(approval No. 201601006) on July 29, 2016.展开更多
Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydr...Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydrogel using a strategy that has been developed to prepare dual-network(DN) hydrogels. A hydrophobic rhodamine derivative(Rh mechanophore) was covalently incorporated into a first network as a cross-linker. This first network embedded with Rh mechanophore within the DN hydrogel was pre-stretched. This guaranteed that the stress could be transferred extensively to the Rh-crosslinked first network once the hydrogel was under an applied force. Interestingly, we found that the threshold stress required to activate the mechanochromism of the hydrogel was less than 200 kPa, and much less than those in previous reports. Moreover, because of the excellent sensitivity of the hydrogel to stress, the DN hydrogel exhibited reversible freezing-induced mechanochromism. Benefiting from the sensitivity of Rh mechanophore to both p H and force, the DN hydrogel showed p H-regulated mechanochromic behavior. Our experimental results indicate that the preparation strategy we used introduces sensitive mechanochromism into the hydrogel and preserves the advantageous mechanical properties of the DN hydrogel. These results will be beneficial to the design and preparation of mechanochromic hydrogels with high stress sensitivity, and foster their practical applications in a number of fields such as damage reporting and stress/strain sensing.展开更多
A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl...A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles （VSNPs） as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels （H gels） and a series of poly（acrylamide-co-dimethylacrylamide） （P（AM-co-DMAA）） NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles （SNPs）. Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P（AM-co-DMAA） NCP gels, the P（AM-co- DMAA） chains are grafted on VSNPs and the polydimethylacrylamide （PDMAA） only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P（AM-co-DMAA） NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.展开更多
Developing a low-cost and well-recyclable adsorbent with high adsorption capacity is greatly desirable in dye wastewater treatment. Here, we demonstrate a kind of novel tough and reusable hydrogel beads with quite hig...Developing a low-cost and well-recyclable adsorbent with high adsorption capacity is greatly desirable in dye wastewater treatment. Here, we demonstrate a kind of novel tough and reusable hydrogel beads with quite high capacity of dye adsorption via incorporating mussel-bioinspired poly（L-DOPA） （PDOPA） into alginate/poly（acrylamide） double network （DN） hydrogels. The synthesized PDOPA nanoaggregates were introduced into the DN hydrogels by simple one-pot mixing with the monomers prior to polymerization. The fabricated hydrogel beads exhibited high mechanical strength and good elastic recovery due to the interpenetrating Ca2＋-alginate and poly（acrylamide） networks. It was shown that the beads exhibited relatively high dye adsorption capacity compared to other adsorbents reported in literature, and the introduction of PDOPA with an appropriate amount raised the adsorption capacity. It is believed that the addition of PDOPA and the matrix of double network architecture contributed synergistically to the high adsorption capacity of hydrogel beads. Moreover, the desorption of dyes could be easily realized via rinsing in acidic water and ethanol solution. The hydrogel beads remained the high adsorption capacity even after 5 times of adsorption and desorption cycles. This tough and stable hydrogel with high adsorption capacity may have potential in treatment of dye wastewater released by textile dyeing industry.展开更多
We developed a fluorescent double network hydrogel with ionic responsiveness and high mechanical properties for visual detection.The nanocomposite hydrogel of laponite and polyacrylamide serves as the first network,wh...We developed a fluorescent double network hydrogel with ionic responsiveness and high mechanical properties for visual detection.The nanocomposite hydrogel of laponite and polyacrylamide serves as the first network,while the ionic cross-linked hydrogel of terbium ions and sodium alginate serves as the second network.The double-network structure,the introduction of nanoparticles and the reversible ionic crosslinked interactions confer high mechanical properties to the hydrogel.Terbium ions are not only used as the ionic cross-linked points,but also used as green emitters to endow hydrogels with fluorescent properties.On the basis of the “antenna effect” of terbium ions and the ion exchange interaction,the fluorescence of the hydrogels can make selective responses to various ions(such as organic acid radical ions,transition metal ions) in aqueous solutions,which enables a convenient strategy for visual detection toward ions.Consequently,the fluorescent double network hydrogel fabricated in this study is promising for use in the field of visual sensor detection.展开更多
The interpenetrating polymer network(IPN) silicone hydrogels with improved oxygen permeability and mechanical strength were prepared by UV-initiated polymerization of monomers including methacryloxypropyl tris(trimeth...The interpenetrating polymer network(IPN) silicone hydrogels with improved oxygen permeability and mechanical strength were prepared by UV-initiated polymerization of monomers including methacryloxypropyl tris(trimethylsiloxy)silane(TRIS),2-hydroxyethylmethacrylate(HEMA) and N-vinyl pyrrolidone(NVP) in the presence of free radical photoinitiator and cationic photoinitiator.The polymerization mechanism was investigated by the formation of gel network.The structure of IPN hydrogels was characterized by Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry(DSC) and transmission electron microscopy(TEM).The results showed that the IPN hydrogels exhibited a heterogeneous morphology.The mechanical properties,surface wettability and oxygen permeability were examined by using a tensile tester,a contact angle goniometer and an oxygen transmission tester,respectively.The equilibrium water content of the hydrogels was measured by the gravimetric method.The results revealed that the IPN hydrogels possessed hydrophilic surface and high water content.They exhibited improved oxygen permeability and mechanical strength because of the incorporation of TRIS.展开更多
The design principles and preparation methods of the double-network hydrogels are reviewed. In addition,the application of the double-network hydrogels in different fields is also introduced.
CTS-g-（AA-co-SS）/ISC hybrid hydrogel adsorbent with crosslinked network structure and superior adsorption performance for rare-earth metal ions was successfully synthesized in aqueous solution by a simple one-step f...CTS-g-（AA-co-SS）/ISC hybrid hydrogel adsorbent with crosslinked network structure and superior adsorption performance for rare-earth metal ions was successfully synthesized in aqueous solution by a simple one-step free-radical grafting polymerization reaction among acrylic acid（AA）, sodium p-styrenesulfonate（SS） and chitosan（CTS） using illite/smectite clay（ISC） as the inorganic additive. The structure of the as-prepared CTS-g-（AA-co-SS）/ISC hydrogel adsorbent was characterized, and the reaction parameters such as AA/SS molar ratio and ISC content were optimized, and the effects of pH values, initial concentration and contact time on the adsorption performance for Ce（Ⅲ） and Gd（Ⅲ） were systematically evaluated. It was found that the maximum adsorption capacities of the hydrogel adsorbent toward Ce（Ⅲ） and Gd（Ⅲ） reached 174.05 and 223.79 mg/g, respectively, and the adsorption quickly achieved equilibrium within 15–20 min. The adsorbed Ce（Ⅲ） and Gd（Ⅲ） could be easily desorbed for recovery, and the used adsorbent was able to be regenerated for reuse. After five adsorption-desorption cycles, the regenerated adsorbent could still retain the adsorption capacities that were close to the initial value. The adsorption process was well described by pseudo-second-order kinetic mode and the Langmuir isotherm model, and the chemical complexation between ions and –COO~–was mainly responsible for the high adsorption capacity. As a whole, the hybrid hydrogel adsorbent was potential to be used for the adsorption and recovery of Ce（Ⅲ） and Gd（Ⅲ） from water.展开更多
Soil aggregation plays an important role in agricultural production activities.However,the structure of soil aggregation is destroyed by the natural environment and unreasonable farming management,resulting in the los...Soil aggregation plays an important role in agricultural production activities.However,the structure of soil aggregation is destroyed by the natural environment and unreasonable farming management,resulting in the loss of water,fertilizers and pesticides in soil.At present,hydrogels have been widely reported to promote the formation of soil aggregation.In this paper,amphiphilic calcium alginate(ASA/Ca^(2+))was applied to promote the formation of soil aggregation and enhance pesticide retention.Initially,an ASA was obtained through the one-pot Ugi condensation(a four-component green chemical reaction).Then,ASA/Ca^(2+) hydrogel is prepared by Ca^(2+) cross-linking.The formation of soil aggregation was determined through the Turbiscan Lab Expert stability analyzer,Confocal Laser Scanning Microscope(CLSM),and Transmission Electron Microscope(TEM).And the effect of soil aggregation on acetamiprid environmental behavior was investigated by adsorption kinetics,adsorption isotherms,and leaching.The results shown that the three-dimensional network structure of ASA/Ca^(2+) hydrogel can promote the formation of soil aggregation.Aggregate durability index(ADI)was 0.55 in the presence of ASA/Ca^(2+) hydrogel,indicating that amphiphilic hydrogel can enhance the stability of soil aggregation.The adsorbing capacity of acetamiprid was 1.58 times higher than pure soil,and the release of acetamiprid only about 20%in the presence of ASA/Ca^(2+) hydrogel.These results would be helpful for the formation of soil aggregation and pesticides adsorption on soil aggregation.Thus,ASA/Ca^(2+) hydrogel is likely to improve soil quality,simultaneously it can minimize the mobility of pesticides in the agricultural system.展开更多
基金supporting from Shanghai Pujiang Program(23PJ1400400)DHU startup grant,the Fundamental Research Funds for the Central Universities,DHU Distinguished Young Professor Program.
文摘The root system actively reacts to mechanical stimuli in its environment,transmitting mechanical signals to optimize the utilization of environmental resources.While the mechanical impedance created by the growth medium serves as the primary source of stimulation for the roots,extensive research has focused on the roots'response to static mechanical stimulation.However,the impact of dynamic mechanical stimulation on root phenotype remains underexplored.In this study,we utilized a low acyl gellan gum/polyacrylamide(GG/PAM)double network elastic hydrogel as the growth medium for rapeseed.We constructed a mechanical device to investigate the effects of reciprocating extrusion stimulation on the growth of the rapeseed root system.After three weeks of mechanical stimulation,the root system exhibited a significant increase in lateral roots.This branching enhanced the roots'anchoring and penetration into the hydrogel,thereby improving the root system's adaptability to its environment.Our findings offer valuable data and insights into the effects of reciprocating mechanical stimulation on root growth,providing a new way for engineering root phenotype.
基金financially supported by the National Natural Science Foundation of China(Nos.52073256,21404091 and 21404089)the Zhejiang Provincial Natural Science Foundation of China(No.LBY21E030001)。
文摘Hydrogels with good antifouling and mechanical properties as well as biocompatibility have great application potential in the field of biomedicine.In this paper,a newly double network(DN)hydrogel was prepared based on zwitterionic material sulfobetaine methacrylate(SBMA)and natural polysaccharide,sodium alginate(SA).The PSBMA network is covalently crosslinked while the SA network is ionically crosslinked by Ca^(2+).The hybrid crosslinked double network structure endows the DN hydrogel with excellent mechanical properties(E=0.19±0.01 MPa,σ=0.73±0.03 MPa),fast self-recovery ability as well as excellent fatigue resistance.Moreover,the results show that the PSBMA/SA-Ca^(2+)DN hydrogel is biocompatible and resists the absorption of non-specific proteins and adhesion of microorganisms,such as cells and algae,exhibiting outstanding antifouling properties.These unique characteristics of PSBMA/SA-Ca^(2+)DN hydrogel make it a promising candidate for biomedical application,such as artificial connective tissues,implantable devices,and underwater equipment.
基金supported by the National Natural Science Foundation of China (No.51273189)the National Science and Technology Major Project of the Ministry of Science and Technology of China (No.2016ZX05016),the National Science and Technology Major Project of the Ministry of Science and Technology of China (No.2016ZX05046)
文摘Double network(DN)hydrogels as one kind of tough gels have attracted extensive at-tention for their potential applications in biomedical and load-bearing fields.Herein,we import more functions like shape memory into the conventional tough DN hydro-gel system.We synthesize the PEG-PDAC/P(AAm-co-AAc)DN hydrogels,of which the first network is a well-defined PEG(polyethylene glycol)network loaded with PDAC(poly(acryloyloxyethyltrimethyl ammonium chloride))strands,while the second network is formed by copolymerizing AAm(acrylamide)with AAc(acrylic acid)and cross-linker MBAA(N;N′-methylenebisacrylamide).The PEG-PDAC/P(AAm-co-AAc)DN gels exhibits high mechanical strength.The fracture stress and toughness of the DN gels reach up to 0.9 MPa and 3.8 MJ/m^3,respectively.Compared with the conventional double network hydrogels with neutral polymers as the soft and ductile second network,the PEG-PDAC/P(AAm-co-AAc)DN hydrogels use P(AAm-co-AAc),a weak polyelectrolyte,as the second network.The AAc units serve as the coordination points with Fe^3+ions and physically crosslink the second network,which realizes the shape memory property activated by the reducing ability of ascorbic acid.Our results indicate that the high mechanical strength and shape memory properties,probably the two most important characters related to the potential application of the hydrogels,can be introduced simultaneously into the DN hydrogels if the functional monomer has been integrated into the network of DN hydrogels smartly.
基金supported by the High Levels of Health Technical Personnel in Beijing Health System of China,No.2013-3-050(to JZY)
文摘Current animal models of nerve root compression due to lumbar disc herniation only assess the mechanical compression of nerve roots and the inflammatory response. Moreover, the pressure applied in these models is static, meaning that the nerve root cannot be dynamically compressed. This is very different from the pathogenesis of lumbar disc herniation. In this study, a chitosan/polyacrylamide double-network hydrogel was prepared by a simple two-step method. The swelling ratio of the double-network hydrogel increased with prolonged time, reaching 140. The compressive strength and compressive modulus of the hydrogel reached 53.6 and 0.34 MPa, respectively. Scanning electron microscopy revealed the hydrogel's crosslinked structure with many interconnecting pores. An MTT assay demonstrated that the number of viable cells in contact with the hydrogel extracts did not significantly change relative to the control surface. Thus, the hydrogel had good biocompatibility. Finally, the double-network hydrogel was used to compress the L4 nerve root of male sand rats to simulate lumbar disc herniation nerve root compression. The hydrogel remained in its original position after compression, and swelled with increasing time. Edema appeared around the nerve root and disappeared 3 weeks after operation. This chitosan/polyacrylamide double-network hydrogel has potential as a new implant material for animal models of lumbar nerve root compression. All animal experiments were approved by the Animal Ethics Committee of Neurosurgical Institute of Beijing, Capital Medical University, China(approval No. 201601006) on July 29, 2016.
基金financially supported by the National Natural Science Foundation of China (No. 51273189)the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2016ZX05016)the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2016ZX05046)
文摘Mechanochromic hydrogels, a new class of stimuli-responsive soft materials, have potential applications in a number of fields such as damage reporting and stress/strain sensing. We prepared a novel mechanochromic hydrogel using a strategy that has been developed to prepare dual-network(DN) hydrogels. A hydrophobic rhodamine derivative(Rh mechanophore) was covalently incorporated into a first network as a cross-linker. This first network embedded with Rh mechanophore within the DN hydrogel was pre-stretched. This guaranteed that the stress could be transferred extensively to the Rh-crosslinked first network once the hydrogel was under an applied force. Interestingly, we found that the threshold stress required to activate the mechanochromism of the hydrogel was less than 200 kPa, and much less than those in previous reports. Moreover, because of the excellent sensitivity of the hydrogel to stress, the DN hydrogel exhibited reversible freezing-induced mechanochromism. Benefiting from the sensitivity of Rh mechanophore to both p H and force, the DN hydrogel showed p H-regulated mechanochromic behavior. Our experimental results indicate that the preparation strategy we used introduces sensitive mechanochromism into the hydrogel and preserves the advantageous mechanical properties of the DN hydrogel. These results will be beneficial to the design and preparation of mechanochromic hydrogels with high stress sensitivity, and foster their practical applications in a number of fields such as damage reporting and stress/strain sensing.
基金financially supported by the National Natural Science Foundation of China(Nos.21474058 and 51633003)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(No.LK1404)+1 种基金Tsinghua University Scientific Research Project(No.2014Z22069)State Key Laboratory of Organic-Inorganic Composites,Beijing University of Chemical Technology(No.OIC-201601006)
文摘A facile method to fabricate tough and highly stretchable polyacrylamide （PAM） nanocomposite physical hydrogel （NCP gel） was proposed. The hydrogels are dually crosslinked single network with the PAM grafted vinyl hybrid silica nanoparticles （VSNPs） as the analogous covalent crosslinking points and the reversible hydrogen bonds among the PAM chains as the physical crosslinking points. In order to further elucidate the toughening mechanism of the PAM NCP gel, especially to understand the role of the dual crosslinking points, the PAM hybrid hydrogels （H gels） and a series of poly（acrylamide-co-dimethylacrylamide） （P（AM-co-DMAA）） NCP gels were designed and fabricated. Their mechanical properties were compared with those of the PAM NCP gels. The PAM H gels are prepared by simply mixing the PAM chains with bare silica nanoparticles （SNPs）. Relative to the poor mechanical properties of the PAM H gel, the PAM NCP gel is remarkably tough and stretchable and also generates large number of micro-cracks to stop notch propagation, indicating the important role of PAM grafted VSNPs in toughening the NCP gel. In the P（AM-co-DMAA） NCP gels, the P（AM-co- DMAA） chains are grafted on VSNPs and the polydimethylacrylamide （PDMAA） only forms very weak hydrogen bonds between themselves. It is found that mechanical properties of the PAM NCP gel, such as the tensile strength and the elongation at break, are enhanced significantly, but those of the P（AM-co-DMAA） NCP gels decreased rapidly with decreasing AM content. This result reveals the role of the hydrogen bonds among the grafted polymer chains as the physical crosslinking points in toughening the NCP gel.
基金supported by the National Natural Science Foundation of China(Nos.51573159 and 51273176)the Fundamental Research Funds for the Central Universities(No.2016QNA4032)
文摘Developing a low-cost and well-recyclable adsorbent with high adsorption capacity is greatly desirable in dye wastewater treatment. Here, we demonstrate a kind of novel tough and reusable hydrogel beads with quite high capacity of dye adsorption via incorporating mussel-bioinspired poly（L-DOPA） （PDOPA） into alginate/poly（acrylamide） double network （DN） hydrogels. The synthesized PDOPA nanoaggregates were introduced into the DN hydrogels by simple one-pot mixing with the monomers prior to polymerization. The fabricated hydrogel beads exhibited high mechanical strength and good elastic recovery due to the interpenetrating Ca2＋-alginate and poly（acrylamide） networks. It was shown that the beads exhibited relatively high dye adsorption capacity compared to other adsorbents reported in literature, and the introduction of PDOPA with an appropriate amount raised the adsorption capacity. It is believed that the addition of PDOPA and the matrix of double network architecture contributed synergistically to the high adsorption capacity of hydrogel beads. Moreover, the desorption of dyes could be easily realized via rinsing in acidic water and ethanol solution. The hydrogel beads remained the high adsorption capacity even after 5 times of adsorption and desorption cycles. This tough and stable hydrogel with high adsorption capacity may have potential in treatment of dye wastewater released by textile dyeing industry.
基金Funded by the National Natural Science Foundation of China(No.51873167)the National Innovation and Entrepreneurship Training Program for College Students(No.226801001)。
文摘We developed a fluorescent double network hydrogel with ionic responsiveness and high mechanical properties for visual detection.The nanocomposite hydrogel of laponite and polyacrylamide serves as the first network,while the ionic cross-linked hydrogel of terbium ions and sodium alginate serves as the second network.The double-network structure,the introduction of nanoparticles and the reversible ionic crosslinked interactions confer high mechanical properties to the hydrogel.Terbium ions are not only used as the ionic cross-linked points,but also used as green emitters to endow hydrogels with fluorescent properties.On the basis of the “antenna effect” of terbium ions and the ion exchange interaction,the fluorescence of the hydrogels can make selective responses to various ions(such as organic acid radical ions,transition metal ions) in aqueous solutions,which enables a convenient strategy for visual detection toward ions.Consequently,the fluorescent double network hydrogel fabricated in this study is promising for use in the field of visual sensor detection.
基金supported by the National Natural Science Foundation of China(Nos.50573011 and 50673019)
文摘The interpenetrating polymer network(IPN) silicone hydrogels with improved oxygen permeability and mechanical strength were prepared by UV-initiated polymerization of monomers including methacryloxypropyl tris(trimethylsiloxy)silane(TRIS),2-hydroxyethylmethacrylate(HEMA) and N-vinyl pyrrolidone(NVP) in the presence of free radical photoinitiator and cationic photoinitiator.The polymerization mechanism was investigated by the formation of gel network.The structure of IPN hydrogels was characterized by Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry(DSC) and transmission electron microscopy(TEM).The results showed that the IPN hydrogels exhibited a heterogeneous morphology.The mechanical properties,surface wettability and oxygen permeability were examined by using a tensile tester,a contact angle goniometer and an oxygen transmission tester,respectively.The equilibrium water content of the hydrogels was measured by the gravimetric method.The results revealed that the IPN hydrogels possessed hydrophilic surface and high water content.They exhibited improved oxygen permeability and mechanical strength because of the incorporation of TRIS.
文摘The design principles and preparation methods of the double-network hydrogels are reviewed. In addition,the application of the double-network hydrogels in different fields is also introduced.
基金Project supported by the National Natural Science Foundation of China(51403221,21377135,U1407114)the“863”Project of the Chinese Ministry of Science and Technology(2013AA032003)
文摘CTS-g-（AA-co-SS）/ISC hybrid hydrogel adsorbent with crosslinked network structure and superior adsorption performance for rare-earth metal ions was successfully synthesized in aqueous solution by a simple one-step free-radical grafting polymerization reaction among acrylic acid（AA）, sodium p-styrenesulfonate（SS） and chitosan（CTS） using illite/smectite clay（ISC） as the inorganic additive. The structure of the as-prepared CTS-g-（AA-co-SS）/ISC hydrogel adsorbent was characterized, and the reaction parameters such as AA/SS molar ratio and ISC content were optimized, and the effects of pH values, initial concentration and contact time on the adsorption performance for Ce（Ⅲ） and Gd（Ⅲ） were systematically evaluated. It was found that the maximum adsorption capacities of the hydrogel adsorbent toward Ce（Ⅲ） and Gd（Ⅲ） reached 174.05 and 223.79 mg/g, respectively, and the adsorption quickly achieved equilibrium within 15–20 min. The adsorbed Ce（Ⅲ） and Gd（Ⅲ） could be easily desorbed for recovery, and the used adsorbent was able to be regenerated for reuse. After five adsorption-desorption cycles, the regenerated adsorbent could still retain the adsorption capacities that were close to the initial value. The adsorption process was well described by pseudo-second-order kinetic mode and the Langmuir isotherm model, and the chemical complexation between ions and –COO~–was mainly responsible for the high adsorption capacity. As a whole, the hybrid hydrogel adsorbent was potential to be used for the adsorption and recovery of Ce（Ⅲ） and Gd（Ⅲ） from water.
基金suppoted by the Key Projects in the Hainan provincial Science&Technology Program(No.ZDYF2020191)the National Natural Science Foundation of China(Nos.22068011,22007025)+1 种基金the Natural Science Foundation of Hainan Province(Nos.220MS006,220QN182)the Start-up Grants from Hainan University(Nos.KYQD(ZR)20041,KYQD(ZR)20040).
文摘Soil aggregation plays an important role in agricultural production activities.However,the structure of soil aggregation is destroyed by the natural environment and unreasonable farming management,resulting in the loss of water,fertilizers and pesticides in soil.At present,hydrogels have been widely reported to promote the formation of soil aggregation.In this paper,amphiphilic calcium alginate(ASA/Ca^(2+))was applied to promote the formation of soil aggregation and enhance pesticide retention.Initially,an ASA was obtained through the one-pot Ugi condensation(a four-component green chemical reaction).Then,ASA/Ca^(2+) hydrogel is prepared by Ca^(2+) cross-linking.The formation of soil aggregation was determined through the Turbiscan Lab Expert stability analyzer,Confocal Laser Scanning Microscope(CLSM),and Transmission Electron Microscope(TEM).And the effect of soil aggregation on acetamiprid environmental behavior was investigated by adsorption kinetics,adsorption isotherms,and leaching.The results shown that the three-dimensional network structure of ASA/Ca^(2+) hydrogel can promote the formation of soil aggregation.Aggregate durability index(ADI)was 0.55 in the presence of ASA/Ca^(2+) hydrogel,indicating that amphiphilic hydrogel can enhance the stability of soil aggregation.The adsorbing capacity of acetamiprid was 1.58 times higher than pure soil,and the release of acetamiprid only about 20%in the presence of ASA/Ca^(2+) hydrogel.These results would be helpful for the formation of soil aggregation and pesticides adsorption on soil aggregation.Thus,ASA/Ca^(2+) hydrogel is likely to improve soil quality,simultaneously it can minimize the mobility of pesticides in the agricultural system.
