• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    A green MXene-based organohydrogel with tunable mechanics and freezing tolerance for wearable strain sensors

    2022-06-20 06:22:52ShuoLiuXinyuTinXinshengZhngChongzhiXuLiliWngYnzhiXi
    Chinese Chemical Letters 2022年4期

    Shuo Liu,Xinyu Tin,Xinsheng Zhng,b,c,*,Chongzhi Xu,Lili Wng,**,Ynzhi Xi

    a State Key Laboratory of Bio-Fibers and Eco-Textiles,College of Textiles and Clothing,Collaborative Innovation Center for Marine Biomass Fibers,Materials and Textiles of Shandong Province,Institute of Marine Biobased Materials,Qingdao University,Qingdao 266071,China

    b Key Laboratory of Clean Dyeing and Finishing Technology of Zhejiang Province,Shaoxing University,Shaoxing 312000,China

    c Research Center for Intelligent and Wearable Technology,Intelligent Wearable Engineering Research Center of Qingdao,Qingdao University,Qingdao 266071,China

    ABSTRACT Conductive hydrogels have attracted considerable attention owing to their potential for use as electronic skin and sensors.However,the loss of the inherent elasticity or conductivity in cold environments severely limits their working conditions.Generally,organic solvents or inorganic salts can be incorporated into hydrogels as cryoprotectants.However,their toxicity and/or corrosive nature as well as the significant water loss during the solvent exchange present serious difficulties.Herein,a liquid-like yet non-toxic polymer-polyethylene glycol(PEG)was attempted as one of the components of solvent for hydrogels.In the premixed PEG-water hybrid solvent,polyacrylamide(PAAm)was in situ polymerized,overcoming the inevitable water loss induced by the high osmotic pressure of the PEG solution and achieving tailored water capacity.Interestingly,the mechanical strength(“soft-to-rigid”transition)and anti-freezing properties of organohydrogels can be simultaneously tuned over a very wide range through adjusting PEG content.This was due to that with increasing PEG in solvent,the PAAm chains transformed from stretching to curling conformation,while PEG bonded with water molecules via hydrogen bonds,weakening the crystallization of water at subzero temperature.Additionally,a highly conductive Ti3C2Tx-MXene was further introduced into the organohydrogels,achieving a uniform distribution triggered by the attractive interaction between the rich functional groups of the nanofillers and the polymer chains.The nanocomposite hydrogels demonstrate high electrical conductivity and strain sensitivity,along with a wide working temperature window.Such a material can be used for monitoring human joint movement even at low temperature and has potential applications in wearable strain sensors.

    Keywords:Organohydrogel Mechanical performance Temperature tolerance Strain sensor MXene

    Hydrogels are characterized by a three-dimensional network,which is composed of chemically or physically crosslinked polymer chains,surrounded by a large amount of water[1–4].Owing to their unique advantageous properties,including flexibility and high water content[5–8],they are widely used in various fields,such as tissue engineering and wearable electronics[9–13].However,extreme environments severely limit the applications of hydrogels due to a reduction in their performance.In particular,under low-temperature conditions,traditional hydrogels freeze,and thus,their flexibility,conductivity,and transparency are lost[14–17].To overcome this difficulty,in recent years,the development of anti-freezing hydrogels has attracted widespread attention.

    As seen in the literature,the incorporation of cryoprotectants into hydrogels has become a popular approach for fabricating antifreezing hydrogels.Cryoprotectants are mainly divided into the following three categories:(1)The freezing point of the water phase in the hydrogel can be effectively reduced by introducing inorganic salts(such as LiCl,CaCl2and ZnCl2);these salts endow the hydrogel with anti-freezing properties[18,19].Zhanget al.[20]introduced a mixture of ZnCl2/CaCl2into the cellulose hydrogel network,and the obtained inorganic salt–water gel retained excellent stretchability and toughness at low temperature.Morelleet al.[18]added CaCl2to the popular polyacrylamide(PAAm)/alginate double-network hydrogel.The inorganic salts not only inhibited the formation of ice crystals at low temperature but also endowed the hydrogel with ionic conductivity.The hydrogel exhibited superior electrical and tensile properties at a temperature of-57 °C.(2)Inspired by the fact that plants in nature can survive in ultra-low temperature environments,researchers have developed a series of binary solvent systems(including ethylene glycol or glycerol/water,betaine or proline/water,and ammonium hydroxide/water)based on the mechanism that inhibits the freezing of water through the introduction of lipids into cell membranes.Organic solvents are usually introduced into the hydrogel using the solvent replacement method[21–24],producing what are known as“organohydrogels”.Commonly used organic solvents include ethylene glycol(EG),dimethyl sulfoxide(DMSO),and glycerol[25,26].Suiet al.[27]introduced zwitterionic penetrants(betaine and proline)into the hydrogelviasolvent replacement.The resulting hydrogels exhibited excellent ionic conductivity at a temperature of-40 °C.The cationic groups of betaine and the anionic groups of proline formed hydrogen bonds with water moleculesviaelectrostatic-induced hydration.This hydrogen bond formation destroyed the inherent hydrogen bond network between the water molecules and thus hampered the crystallization of the water molecules.Moet al.[28]designed an anti-freezing hydrogel electrolyte by adding ethylene glycol monounsaturated fatty acid(EG-waPUA).Water molecules enhanced the interaction between the EG-WaPUA and the PAAm polymer chains.These interactions firmly locked the water molecules into the polymer network and disrupted lattice formation at low temperatures.Thus,the hydrogels obtained freezing resistance and maintained a high ionic conductivity at-20 °C.Yeet al.[29]used DMSO to induce the sol–gel conversion of a polyvinyl alcohol/cellulose nanofiber aqueous solution,in which hydrogen bonding interaction was formed between DMSO and the water molecules.The resulting hydrogels retained flexibility,conductivity,high stretchability,and high transparency at-70 °C.Liaoet al.[30]immersed MXene nanocomposite hydrogels into EG to replace a part of the water molecules.Hydrogen bonds were generated between EG and the water molecules,which destroyed the formation of ice crystals and endowed the hydrogels with freezing resistance.A hydrogel with excellent self-healing ability,mechanical properties,and electrical conductivity at-40 °C was successfully fabricated using this method.(3)Anti-freezing hydrogels can be obtained through the combined use of inorganic salts and organic solvents.Louet al.[31]designed a novel complex solvent system(EG/LiCl),where LiCl had high solubility in ethylene glycol.Under the joint action of inorganic salts and organic solvents,the obtained hydrogel maintained high toughness at-80 °C and electrical conductivity at-20 °C.The above investigations indicate that the introduction of organic solvents or inorganic salts using the solvent displacement method can endow hydrogels with improved anti-freezing properties,thus effectively broadening their working temperature range[32,33].However,these methods and their practical applications still have some issues.For example,most of the cryoprotectant agents,especially in the case of organic anti-freezing solvents(such as EG and DMSO),are toxic,and some effective inorganic salts(such as LiCl)are corrosive.More importantly,the water content of the hydrogel is significantly reduced during the solvent replacement process,thus sacrificing their inherent high water content and flexibility.The challenge therefore remains to develop a nontoxic,anti-freezing hydrogel with controllable water content.

    Fig.1.Schematic diagram of the arrangement of polymer chains for PAAm PEGbased hydrogels.(a) Cw,PEG = 0%.(b) Cw,PEG = 50%.(c) Cw,PEG = 60%.(d) Cw,PEG = 80%.(Cw,PEG200 represents the concentration of PEG200, Tc represents the crystallization temperature of water in the hydrogel,and σf represents the breaking strength of hydrogel.)

    We note that single molecules of EG exhibit toxicity,but the toxicity is greatly reduced after polymerizing them into polymer polyethylene glycol(PEG).For this reason,a green non-toxic PEG was investigated as a possible anti-freezing agent.In this context,the significant loss of water content due to the osmotic pressure of PEG upon solvent replacement is a major challenge(Fig.S1 in Supporting information).Here,the PAAm monomer and auxiliary agents with better solubility in PEG were chosen,and thein situpolymerization was undertaken in the as-prepared PEG/H2O binary solvent,thus successfully obtaining green organohydrogels with tailored water content.The influence of the molecular weight of PEG,the concentration of PEG in binary solvents,and the weight fraction of PAAm on the anti-freezing performance and mechanical properties was systematically explored.PAAm hydrogels were found to exhibit three states upon varying the PEG content in the binary solvents(Fig.1).Within the low-PEG-content regime(Fig.1b),a large number of water molecules were located around PAAm chains,giving the polymer chains a free state.In this case,the hydrogel was transparent and flexible,and its appearance was similar to that of the pure water PAAm hydrogel(Fig.1a).With the increase in the PEG concentration(Fig.1c),the number of water molecules around PAAm molecular chains was reduced,which was induced by the reduction of the water content and the attraction of water molecules to PEG,leading to the gradual approach of PAAm chains.Here,the mobility of the polymer chains and the transparency of the hydrogels decreased.When the PEG concentration reached its peak(Fig.1d),rare water molecules could surround with PAAm chains.The phase separation of the PAAm chains was induced in this regime,leading to considerable curling of the polymer chains and thus the white appearance of the hydrogel.It is notable that,with the increase in the PEG concentration,the strength and anti-freezing performance of the hydrogels increased,but the resilience of the hydrogel gradually decreased.In summary,PEG molecules were introducedin situto effectively regulate the aggregation of the polymer chains in hydrogels and were found to simultaneously generate a hydrogen bonding interaction with water molecules,achieving the tunability of mechanical properties and anti-freezing properties of the hydrogels.

    Fig.2.(a)Phase diagram of constituents-temperature-frozen state for PEG200/H2O binary solvent.(b)The effect of PEG molecular weight on the transition temperature of liquid state to liquid solid coexistence state.(c)The morphology of PEG200/H2O binary solvent at different temperatures(Cw,PEG200 of binary solvent from left to right in each figure is 100%,80%,70%,60%,50%,40%,30%,20% and 0%).

    The effects of the PEG concentration in the PEG/H2O binary solvent and the molecular weight of PEG on the freezing resistance of the mixed solution are presented in Fig.2.The phase diagram depicting the PEG concentration,temperature,and state of the PEG200/H2O binary solvent is presented in Fig.2a.The phase diagram is divided into three regions,namely,the liquid region(unfrozen state),the liquid–solid coexistence region(semi-frozen state),and the solid region(completely frozen state).The specific frozen state of the EG/H2O and PEG/H2O binary solvents with various values ofCw,EGandCw,PEGwas derived from their frozen state using a refrigerator at different temperatures(Fig.2c and Fig.S2 in Supporting information).For example,with Cw,PEG200= 60%,the mixed solution was found to remain in its liquid state when kept at a temperature of-20 °C for 24 h(Figs.2c-i and a-i).The mixed solution also remained its liquid state(Figs.2c-ii and aii)when exposed to-50 °C for 24 h,whereas it became solid when kept at-80 °C for 24 h(Figs.2c-iii and a-iii).As the temperature decreased,the binary solvent first transitioned from a liquid state to a liquid–solid coexistence state and then transformed from the liquid–solid coexistence state to a solid state.The PEG concentration of the binary solvent played a significant role in determining its anti-freezing performance.Within the regime ofCw,PEG200<75%,the temperatures of the transitions from the liquid state to the liquid–solid coexistence state and from the liquid–solid coexistence state to the solid state of the binary solvent gradually decreased with the increase inCw,PEG200,indicating an improved freezing resistance with increasingCw,PEG200.WhenCw,PEG200was higher than 80%,the abovementioned transition temperatures gradually increased with the increase inCw,PEG200,indicating that,above this threshold,the freezing resistance was gradually weakened with increasingCw,PEG200.WhenCw,PEG200was in the range of 75%–80%,the mixed solution was still not completely frozen even when exposed to temperatures of-80 °C for 24 h(Fig.2c),indicating that this solvent had the strongest freezing resistance.The correlation between the PEG concentration in binary solvents and the corresponding anti-freezing ability is due to the fact that,within the low-PEG-concentration regime,with the increase in the PEG concentration,more water molecules are capable of bonding with the PEG molecules forming hydrogen bonds.As a result,the number of free water molecules decreases,reducing the content of low-temperature-induced crystallized water molecules and thus enhancing the anti-freezing performance of the binary solvent.However,within the high-PEG-concentration regime(>80%),the number of water molecules in the system decreases,and the number of free PEG molecules thus increases.In this case,more PEG molecules crystallize at low temperature,leading to the poor anti-freezing performance.

    In addition,by comparing the transitions of the liquid state to the liquid–solid coexistence state for PEG/H2O solvents with different PEG molecular weights(MWPEG)(Fig.2b),it can be observed that the temperature of the binary solvent state transition gradually increases with the increase in the PEG molecular weight.Under the same PEG concentration,the anti-freezing performance of the binary solvent becomes stronger with the decrease in MWPEG.In most work reported in the literature,researchers adopt EG as an anti-freezing agent[26,30].This may be due to the fact that,as the MWPEGincreases,PEG transforms from a colorless,viscous liquid state into a solid wax state.This transition is accompanied by a gradual increase in solution viscosity,which results in a significantly decreased solubility of PEG in binary solvents.In other words,for large MWPEG,the dispersion degree of PEG and water molecules is reduced,and the water molecules cannot effectively bond with the PEG chains,leading to the observed poor freezing resistance of the mixed solution.Considering both the freezing resistance and solvent toxicity,PEG200 was selected as one component of the binary solvents used to prepare green anti-freezing organohydrogels.

    In order to prepare the anti-freezing flexible PAAm hydrogel that can meet the requirements of low temperature environment in winter,northern cities(Heilongjiang,China,etc.)and Antarctica,PEG200/H2O(Cw,PEG200= 80%,70%,60%,50%)with superior anti-freezing properties was chosen as the solvent.The mechanical performance of the PAAm PEG-based hydrogels is presented in Fig.3.The stress–strain curves of the PAAm PEG-based hydrogels in the case ofCw,AAm= 30% with different Cw,PEGare presented in Fig.3a.With increasingCw,PEG,the fracture strength(σf)of the hydrogels increases,but the strain at breakage(εf)decreases,indicating a“soft-to-rigid”transition of the hydrogel.We therefore find that the mechanical parameters of the PAAm PEG-based hydrogels can be tuned over an extraordinarily broad range by varying the content of PEG in the binary solvent.For instance,when Cw,PEG= 50%,theεfof the hydrogel was 10.5,whereasσfwas only 50 kPa,indicating that the sample had the properties of a soft and flexible hydrogel.WhenCw,PEGincreased to 80%,σfcould reach 275 kPa,butεfwas only 1,representing a rigid hydrogel.The influence of the PEG content in the binary solvent on the elastic recovery of the PAAm PEG-based hydrogels is presented in Fig.3d.It can be observed that the area of the hysteretic circle in the tensile cycle curve significantly increases with the increase in strain,especially in the largeCw,PEGregime,indicating the greater energy loss during loading and thus a lower elastic recovery rate of the hydrogel.Therefore,within the regime of low PEG content in the binary solvent,the hydrogel exhibits excellent elastic recovery.This is due to the fact that,with the increase in the PEG concentration in the binary solvent,the number of water molecules around the PAAm molecular chains decreases,which significantly reduces the mobility of the polymer chains.For this reason,the hydrogels exhibit reduced elastic recovery,higher strength,and a white appearance(Fig.3e).The bending performance of the PAAm PEGbased hydrogels frozen at-50 °C for 24 h varied according to their differentCw,PEG(Fig.3e):the hydrogel withCw,PEG= 0% became white;this color arose from the low-temperature-induced crystallization of water molecules.In this case,the hydrogels lost flexibility,and some cracks caused by bending appeared in the samples.This indicates that the neat PAAm hydrogels cannot be used in low-temperature environments;such a restriction is a common issue in hydrogels.However,using PEG/H2O as the solvent,the obtained hydrogels can be bent freely even at a low temperature.

    Fig.3.(a)The stress-strain curves of PAAm PEG-based hydrogels(Cw,AAm = 30%)prepared by different Cw,PEG.(b)Comparison of fracture strength,fracture strain,fracture energy,elastic recovery rate and freezing point of hydrogels in Fig.3a.(c)The stress-strain curves of PAAm PEG-based hydrogels(Cw,PEG = 70%)prepared by different Cw,AAm.(d)The tensile cycle curves of PAAm PEG-based hydrogels(Cw,AAm = 30%)with Cw,PEG = 50%,60% and 70%,respectively.(e)The bending morphology of PAAm PEG-based hydrogels(Cw,AAm = 30%)with different Cw,PEG after frozen at-50 °C for 24 h.

    To explore the effect of the AAm content(Cw,AAm)on the ultimate performance of the PAAm hydrogels,the binary solvent(Cw,PEG= 70%)with the best anti-freezing performance was chosen,and the mechanical properties obtained with varyingCw,AAmwere established(Fig.3c).As can be seen from the Fig.3c,with the increase inCw,AAm,the fracture strength of the hydrogels gradually increases,but the fracture strain decreases.In the case of lowCw,AAm,a low density of polymer chains or a sufficient number of water molecules around the polymer chains leads to weak polymer entanglement and hydrogen bonding interactions,giving rise to a high mobility of the PAAm chains and thus the ductile nature of the hydrogel.WhenCw,AAmbecomes too high,the increased density of polymer chains or the reduced number of water molecules around the PAAm chains enhances polymer entanglement and hydrogen bonding interactions,resulting in a decreased mobility of the polymer chains and thus a poor elasticity of the hydrogels.It was thus found that the mechanical parameters of the PAAm PEG-based hydrogels can be regulated in a wide range by adjustingCw,AAm.

    In conclusion,we compare the properties of hydrogels with different PEG concentrations(Fig.3b):the hydrogels withCw,PEG= 50% exhibit fracture strain of 10.5,fracture strength of 50 kPa,toughness of 258 kJ/m3,and elastic recovery rate of 80%.The obtained hydrogels demonstrate high flexibility,ductility,and resilience and have a freezing point of as low as-60 °C.These flexible hydrogels are ideal candidates for wearable strain sensors,and their inherent flexibility,elastic recovery,and environmental stability are prerequisites for this application.To demonstrate this possible application,the aforementioned hydrogels withCw,PEG= 50% andCw,AAm= 30% were chosen for use as a matrix for flexible sensors.Furthermore,MXene,a two-dimensional material with excellent electrical conductivity,was introduced into the PAAm PEG-based hydrogels to fabricate an organohydrogel sensor,which can be used in cold environments.

    To demonstrate the possible use of the obtained anti-freezing organohydrogels in the field of wearable sensor,the twodimensional materials,MXene nanosheet,were fabricated using the HF etching method;they were characterized by a large specific surface area and short ion transport path[34,35].In addition,the rich functional groups(-OH,-O,-F)[36,37]on the surface of MXene endowed it with high hydrophilicity,which facilitated their dispersion and strong combination with the organohydrogels.The MXene nanosheets were incorporated into the PAAm PEG-based hydrogelsvia in situpolymerization,making a conductive organohydrogel sensor with high resistance to freezing.After the removal of aluminum atoms in the MAX phase(Ti3AlC2)using an etching agent,the-OH,-O and-F groups in the solution were combined with the bonded unsaturated MX layer units to form MXene.In the transmission electron microscopy(TEM)and atomic force microscopy(AFM)images(Figs.4a and b,respectively),ultra-thin nanosheets with good elimination can be observed.These nanosheets exhibit a single-layer structure with a thickness of about 1.5 nm.These features offer effective MXene conductive pathways in the organohydrogels and thus provide good conductivity to the organohydrogels.

    Fig.4.The TEM(a)and AFM(b)images of MXene nanosheets.(c)The display of flexible PAAm/MXene PEG-based organohydrogels at room temperature.(d)The mechanism of better dispersion of MXene in the organohydrogels.The changes of relative resistance for PAAm/MXene PEG-based organohydrogels at small strain(e)and large strain(f)tensile cycles.

    After the MXene nanosheets were embedded in the PAAm PEGbased hydrogels,the obtained nanocomposite hydrogels demonstrated excellent flexibility(Fig.4c).The overall uniform black appearance of the organohydrogels indicates that MXene nanosheets were evenly distributed in the organohydrogels.This was induced by the formation of a large number of hydrogen bonds between the hydroxyl groups on the surface of MXene and the amino groups in the PAAm chains or the hydroxyl groups in the polyethylene glycol chains(Fig.4d).This bond formation promotes a high dispersion of MXene in the organohydrogel matrix and strong bonding with the organohydrogel matrix(Fig.4c).This strong interaction could be further confirmed by the mechanical properties of PAAm/MXene PEG-based hydrogels(Fig.S3 in Supporting information).When MXene was introduced,the fracture strength of hydrogels increased and the fracture strain decreased to a certain extent.Therefore,the addition of MXene could improve the mechanical strength of the PAAm/MXene PEG-based hydrogels.Tensile cycle testing was also conducted on the nanocomposite organohydrogels in the regime of small(0.2 and 0.8)and large strains(1,3 and 5)while simultaneously evaluating their electromechanical properties.As can be seen from Fig.4e,the organohydrogel has high strain sensitivity in the low-strain regime(tested with strains of 0.2 and 0.8),andΔR/R0demonstrates good stability and reproducibility over prolonged testing.To further test the electromechanical properties under large strain,strains of 1,3 and 5 were selected for tensile cycle testing to obtain theΔR/R0variations(Fig.4f).It can be seen that,in the initial phase of testing,the resistance almost completely recovers,and with the increase in strain,ΔR/R0gradually increases,indicating the sensitivity and long-term electrical stability of the sensor.These properties arise from the fact that the nanocomposite organohydrogels withCw,PEG= 50% andCw,AAm= 30% have excellent ductility and elastic recovery(Fig.3),which enable the organohydrogels to maintain the integrity of structure even when exposed to large strain.This ensures that the electrical signal can be effectively and repeatedly transmitted.It should be pointed out thatΔR/R0slightly increases with the increase in the number of cycles at a large strain of 5.This may be due to the deterioration of the microstructure of the nanocomposite organohydrogels caused when the external strain exceeds the critical value.This critical value is observed where the continuous MXene nanosheets are separated to some degree,and a simultaneous increase in the resistance for the conductive path is observed at this critical strain.In summary,the PAAm/MXene PEGbased organohydrogels demonstrate high strain sensitivity,which thus makes them excellent candidates for use as strain sensors.

    To evaluate the working ability of the above hydrogels under extreme conditions,the stability of the PAAm/MXene PEG-based organohydrogels at low temperature was also investigated.When the hydrogels were frozen at-20 °C for a long time of 24 h,the nanocomposite hydrogels could still bend freely and achieve complex shapes(Fig.5a).This indicates that the PAAm/MXene PEG-based organohydrogels retained their excellent flexibility even at low temperature,thus meeting the deformation requirements of wearable sensors.Additionally,in order to simulate the sensing performance at low temperature as much as possible,the PAAm/MXene PEG-based organohydrogels were frozen in the refrigerator(-20 °C)for a sufficient time of 24 h.After that,the hydrogels were taken out immediately and the measurements of sensing performance was collected,where the whole process took about 1,2 min and guaranteed the low temperature of hydrogels.According to the electromechanical properties under tensile cyclic loading(Fig.5b),the nanocomposite hydrogels retain their strain sensitivity and electrical stability at a low temperature.The relative resistance before and after freezing does not significantly change.The PAAm/MXene PEG-based organohydrogels prepared in this work demonstrated to have high flexibility(Fig.5a)and conductivity(Fig.5b),thus making them an ideal candidate for strain sensors[38–40].These PAAm/MXene PEG-based organohydrogels have many exceptional properties,including good extendibility,toughness,elastic recovery,sensitivity,electrical stability,and freezing resistance(Fig.5c).In view of these properties,the proposed PAAm/MXene PEG-based organohydrogels have high application potential in the field of wearable sensing devices.With this application in mind,a hydrogel strain sensor was attached to the joints of the human body using an adhesive tape and used to monitor joint motion by observing the value ofΔR/R0.As presented in Fig.5d,an organohydrogel strain sensor was attached to a joint on the finger.When the finger was bent by 90°,a simultaneous increase in the relative resistance was observed.In addition,the resistance variations exhibited high repeatability,indicating that the strain sensor has high stability and a rapid response ability.Subsequently,the motion of the wrist joint was monitored using the same method(Fig.5e),and similar variations in resistance were observed.This work indicates that the PAAm/MXene PEG-based organohydrogel strain sensors can be used to detect human motion.They also have potential applications in the fields of flexible,wearable electronic devices and sensors.

    Fig.5.(a)The display of flexible PAAm/MXene PEG-based organohydrogels after frozen at-20 °C for 24 h.(b)The electromechanical properties of PAAm/MXene PEG-based organohydrogels after freezing at-20 °C for 24 h.(c)The schematic diagram of anti-freezing PAAm/MXene PEG-based organohydrogels strain sensor.The applications of PAAm/MXene PEG-based organohydrogels for detection of human motions.The changes of relative resistance with bend of(d)finger and(e)wrist.

    In conclusion,a green anti-freezing PAAm organohydrogel and the corresponding strain sensor were preparedvia in situpolymerization using a non-toxic liquid-like polyethylene glycol as one component of the solvent.The addition of PEG not only regulates the conformation and aggregation state of the PAAm chains but also forms hydrogen bonds with the water molecules,which effectively suppressed the crystallization of water.Therefore,the simultaneous tuning of the mechanical properties and freezing resistance of the hydrogels are achieved by altering PEG content.Considering the tensile properties and resilience of the anti-freezing hydrogels,and with the aim of increasing the functionality of the hydrogels,a highly conductive MXene was introduced into the PAAm PEG-based“organohydrogels”.Interestingly,the MXene nanosheets uniformly distributed in the hydrogel matrix induced by the formation of hydrogen bonds between the functional groups on the surface of MXene and the PAAm chains.The resulting PAAm/MXene nanocomposite organohydrogels demonstrated excellent conductivity and strain sensitivity,which has potential application in the monitoring of human joint motion.This research provides a new method for the preparation of green,anti-freezing,and flexible hydrogel sensors,which have potential application in wearable electronic devices,electrodes,and sensors.

    Declaration of competing interest

    The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

    Acknowledgments

    The current work was financially supported by the National Natural Science Foundation of China(Nos.51803101 and 52003131),Natural Science Foundation of Shandong Province(Nos.ZR2019BEM005 and ZR2019BEM026),China Postdoctoral Science Foundation(No.2021T140352),State Key Laboratory of Bio-Fibers and Eco-Textiles(Qingdao University,Nos.ZKT14,ZKT32,GZRC202016,ZFZ201805),Project of Key Laboratory of Clean Dyeing and Finishing Technology of Zhejiang Province(No.QJRZ1904),Program for Changjiang Scholars and Innovative Research Team in University(No.IRT_14R30)and Taishan Scholar Program of Shandong Province(No.tspd20181208).

    Supplementary materials

    Supplementary material associated with this article can be found,in the online version,at doi:10.1016/j.cclet.2021.09.063.

    国产伦精品一区二区三区四那| 少妇被粗大猛烈的视频| 免费大片黄手机在线观看| 中文在线观看免费www的网站| 熟妇人妻不卡中文字幕| 国产成人aa在线观看| 日本爱情动作片www.在线观看| 久久这里只有精品中国| 国产精品av视频在线免费观看| 日本一本二区三区精品| 91久久精品国产一区二区三区| 一个人看的www免费观看视频| 国产乱来视频区| 国产 一区精品| 久久久精品免费免费高清| 最近最新中文字幕免费大全7| 天堂av国产一区二区熟女人妻| or卡值多少钱| 欧美日本视频| 婷婷色综合www| 国产永久视频网站| 国产成人a区在线观看| 中文字幕人妻熟人妻熟丝袜美| 亚洲精品成人av观看孕妇| 麻豆乱淫一区二区| 99热这里只有精品一区| 别揉我奶头 嗯啊视频| 国产精品久久久久久久久免| 午夜爱爱视频在线播放| 国产美女午夜福利| 国产在视频线精品| 国产免费视频播放在线视频 | 免费在线观看成人毛片| 最近的中文字幕免费完整| 亚洲国产精品成人久久小说| av女优亚洲男人天堂| 日本一二三区视频观看| 麻豆成人午夜福利视频| 国语对白做爰xxxⅹ性视频网站| 91久久精品国产一区二区成人| 久久韩国三级中文字幕| 免费看美女性在线毛片视频| 久久99热这里只频精品6学生| av一本久久久久| 久久久久久久午夜电影| 亚洲国产欧美在线一区| 日韩三级伦理在线观看| 亚洲av福利一区| 国国产精品蜜臀av免费| 激情五月婷婷亚洲| 男女国产视频网站| 18禁在线播放成人免费| 日日摸夜夜添夜夜爱| 亚洲精品久久午夜乱码| 深爱激情五月婷婷| 综合色av麻豆| 深爱激情五月婷婷| 91久久精品国产一区二区成人| 欧美一区二区亚洲| 两个人视频免费观看高清| 男女视频在线观看网站免费| 在线观看免费高清a一片| 啦啦啦中文免费视频观看日本| av在线播放精品| 嫩草影院入口| 18禁在线无遮挡免费观看视频| 亚洲国产精品成人综合色| 春色校园在线视频观看| 精品一区二区三区视频在线| av国产久精品久网站免费入址| 久久久久九九精品影院| 日本一二三区视频观看| 亚洲高清免费不卡视频| 欧美成人一区二区免费高清观看| 亚洲四区av| 国产在视频线精品| 久久韩国三级中文字幕| 一二三四中文在线观看免费高清| 69av精品久久久久久| 久久97久久精品| 毛片一级片免费看久久久久| 性色avwww在线观看| 午夜免费激情av| 一本一本综合久久| 亚洲成人久久爱视频| 免费观看的影片在线观看| 高清欧美精品videossex| 嫩草影院入口| 国产老妇伦熟女老妇高清| 在线 av 中文字幕| 男插女下体视频免费在线播放| 能在线免费看毛片的网站| 午夜福利视频1000在线观看| 丝袜美腿在线中文| 日韩欧美精品免费久久| 一本一本综合久久| 99热6这里只有精品| 成年免费大片在线观看| 乱系列少妇在线播放| 精品一区二区三区视频在线| 十八禁网站网址无遮挡 | 国产精品蜜桃在线观看| 成年免费大片在线观看| 狠狠精品人妻久久久久久综合| 成人美女网站在线观看视频| 精品一区二区三卡| 久久久精品免费免费高清| 日日摸夜夜添夜夜添av毛片| 成人亚洲精品一区在线观看 | 久久久久久久午夜电影| 18禁在线播放成人免费| 日日干狠狠操夜夜爽| 亚洲av一区综合| 国产免费视频播放在线视频 | 黄色一级大片看看| 黄色一级大片看看| 精品不卡国产一区二区三区| av福利片在线观看| 肉色欧美久久久久久久蜜桃 | 少妇高潮的动态图| 看十八女毛片水多多多| av天堂中文字幕网| 欧美xxⅹ黑人| 天天躁夜夜躁狠狠久久av| freevideosex欧美| 97人妻精品一区二区三区麻豆| 日韩大片免费观看网站| 五月伊人婷婷丁香| 国产精品久久久久久精品电影| 七月丁香在线播放| 欧美日韩精品成人综合77777| 色吧在线观看| 高清av免费在线| 免费观看性生交大片5| 深夜a级毛片| 亚洲欧美日韩东京热| 亚洲在线观看片| 五月天丁香电影| 亚洲精品国产成人久久av| 精品人妻视频免费看| 女人久久www免费人成看片| 韩国av在线不卡| 大香蕉97超碰在线| 日本免费a在线| 91久久精品电影网| 亚洲性久久影院| 黄色欧美视频在线观看| 性色avwww在线观看| 国产一区亚洲一区在线观看| 亚洲av日韩在线播放| 国产亚洲精品av在线| 国产一级毛片在线| 人妻少妇偷人精品九色| 国产精品伦人一区二区| 特大巨黑吊av在线直播| 久久久a久久爽久久v久久| av在线老鸭窝| 中国美白少妇内射xxxbb| 久久精品国产亚洲av涩爱| 欧美日韩综合久久久久久| 精品人妻偷拍中文字幕| 亚洲成人精品中文字幕电影| 日韩欧美三级三区| 97在线视频观看| 欧美成人一区二区免费高清观看| 国产亚洲精品久久久com| 欧美丝袜亚洲另类| 狠狠精品人妻久久久久久综合| 内地一区二区视频在线| 老女人水多毛片| 日韩电影二区| 啦啦啦韩国在线观看视频| 午夜免费男女啪啪视频观看| 欧美+日韩+精品| 国产成人freesex在线| 成年版毛片免费区| 欧美日韩精品成人综合77777| 国产精品精品国产色婷婷| 99久久精品国产国产毛片| 别揉我奶头 嗯啊视频| 青春草视频在线免费观看| 大又大粗又爽又黄少妇毛片口| 一级爰片在线观看| 国产精品不卡视频一区二区| 99久久九九国产精品国产免费| 人人妻人人澡人人爽人人夜夜 | 91av网一区二区| 精品久久久久久电影网| 久久精品综合一区二区三区| 国产精品三级大全| 在线观看免费高清a一片| 亚洲国产精品成人久久小说| 中文字幕制服av| 十八禁国产超污无遮挡网站| 97超碰精品成人国产| 美女脱内裤让男人舔精品视频| 两个人的视频大全免费| 边亲边吃奶的免费视频| 亚洲熟女精品中文字幕| 婷婷六月久久综合丁香| 男女边吃奶边做爰视频| 六月丁香七月| 国产精品一区www在线观看| 亚洲美女搞黄在线观看| 99久久精品一区二区三区| 少妇高潮的动态图| 天堂av国产一区二区熟女人妻| 久久久久久久久久成人| 午夜福利在线观看免费完整高清在| 亚洲精品亚洲一区二区| 寂寞人妻少妇视频99o| 欧美高清性xxxxhd video| 97超碰精品成人国产| 亚洲精品aⅴ在线观看| 日本与韩国留学比较| 久久久精品94久久精品| 熟女人妻精品中文字幕| 亚洲av成人精品一区久久| 国产成人一区二区在线| 网址你懂的国产日韩在线| 男女下面进入的视频免费午夜| 天天躁日日操中文字幕| 亚洲美女搞黄在线观看| 国产精品一区二区在线观看99 | 亚洲精品久久久久久婷婷小说| 国内揄拍国产精品人妻在线| 欧美成人一区二区免费高清观看| 老师上课跳d突然被开到最大视频| 可以在线观看毛片的网站| 国产精品一区二区三区四区免费观看| 中文天堂在线官网| 高清av免费在线| 秋霞在线观看毛片| 国产伦理片在线播放av一区| 亚洲av国产av综合av卡| 中国国产av一级| 99热6这里只有精品| 80岁老熟妇乱子伦牲交| 中文天堂在线官网| 欧美精品一区二区大全| 高清在线视频一区二区三区| 日韩视频在线欧美| 伦精品一区二区三区| 1000部很黄的大片| 3wmmmm亚洲av在线观看| 97超视频在线观看视频| 欧美一区二区亚洲| 国产v大片淫在线免费观看| 搞女人的毛片| 亚洲精品,欧美精品| av一本久久久久| 国产av国产精品国产| 国产中年淑女户外野战色| 又爽又黄a免费视频| 成人一区二区视频在线观看| 久久久久久久久久成人| 自拍偷自拍亚洲精品老妇| 淫秽高清视频在线观看| 亚洲欧美清纯卡通| 极品教师在线视频| 一级爰片在线观看| 国产毛片a区久久久久| 国产乱人视频| 精品一区二区免费观看| 在线观看美女被高潮喷水网站| 国产精品久久久久久精品电影小说 | 午夜亚洲福利在线播放| 日韩一区二区三区影片| 日韩视频在线欧美| 夜夜看夜夜爽夜夜摸| 国产成人免费观看mmmm| 69av精品久久久久久| 亚洲欧美一区二区三区国产| 亚洲av中文字字幕乱码综合| 国产免费一级a男人的天堂| 美女国产视频在线观看| 亚洲aⅴ乱码一区二区在线播放| 成人性生交大片免费视频hd| 欧美潮喷喷水| 天堂中文最新版在线下载 | 高清午夜精品一区二区三区| 免费播放大片免费观看视频在线观看| 在线观看免费高清a一片| 久热久热在线精品观看| 亚洲精华国产精华液的使用体验| 久久热精品热| 又粗又硬又长又爽又黄的视频| 国产片特级美女逼逼视频| 国产一区有黄有色的免费视频 | 3wmmmm亚洲av在线观看| 69av精品久久久久久| 国产乱人偷精品视频| 十八禁网站网址无遮挡 | 九九爱精品视频在线观看| 亚洲成色77777| 精华霜和精华液先用哪个| 国产高清国产精品国产三级 | 精品一区二区免费观看| 床上黄色一级片| 精品久久久久久久末码| 又爽又黄a免费视频| 日本免费在线观看一区| 99热网站在线观看| 在线观看免费高清a一片| 欧美日韩亚洲高清精品| 美女黄网站色视频| 久久6这里有精品| 亚洲美女搞黄在线观看| 免费大片黄手机在线观看| 美女大奶头视频| 青青草视频在线视频观看| 99热全是精品| 色5月婷婷丁香| 国产午夜精品久久久久久一区二区三区| 搡老妇女老女人老熟妇| 中文字幕免费在线视频6| 黄色配什么色好看| 亚洲av成人精品一二三区| 在线观看免费高清a一片| 亚洲av不卡在线观看| 精品国产一区二区三区久久久樱花 | 国产亚洲5aaaaa淫片| 日韩av免费高清视频| 午夜激情福利司机影院| 国产午夜精品论理片| 男人舔奶头视频| 欧美性感艳星| 欧美极品一区二区三区四区| av福利片在线观看| 免费电影在线观看免费观看| 亚洲av免费高清在线观看| av专区在线播放| 久久久亚洲精品成人影院| or卡值多少钱| 特大巨黑吊av在线直播| 黄色一级大片看看| 久久这里只有精品中国| 一级毛片我不卡| 国产综合懂色| 天堂中文最新版在线下载 | 纵有疾风起免费观看全集完整版 | 亚洲av日韩在线播放| 在线天堂最新版资源| 成人毛片60女人毛片免费| 亚洲国产高清在线一区二区三| 两个人的视频大全免费| 亚洲av国产av综合av卡| 欧美成人精品欧美一级黄| 婷婷色综合www| 久久久亚洲精品成人影院| 久久99蜜桃精品久久| 日韩强制内射视频| 久久久久久久午夜电影| 一二三四中文在线观看免费高清| 中文字幕免费在线视频6| 三级经典国产精品| 国产精品福利在线免费观看| 美女xxoo啪啪120秒动态图| 麻豆乱淫一区二区| 久久这里有精品视频免费| 国产午夜精品久久久久久一区二区三区| 青春草亚洲视频在线观看| 国产在线一区二区三区精| 欧美日韩一区二区视频在线观看视频在线 | 三级国产精品欧美在线观看| 一本久久精品| 插逼视频在线观看| 一区二区三区乱码不卡18| 伊人久久精品亚洲午夜| 淫秽高清视频在线观看| 亚洲国产日韩欧美精品在线观看| 国产精品女同一区二区软件| 内射极品少妇av片p| 久久精品综合一区二区三区| 久久久欧美国产精品| 国产亚洲午夜精品一区二区久久 | 国产成人精品久久久久久| 午夜免费激情av| 人体艺术视频欧美日本| 高清欧美精品videossex| 插逼视频在线观看| 国产片特级美女逼逼视频| 日本免费在线观看一区| 国产精品嫩草影院av在线观看| 天堂中文最新版在线下载 | 18禁在线播放成人免费| 中文字幕人妻熟人妻熟丝袜美| 国产精品综合久久久久久久免费| 69人妻影院| 国产成人精品一,二区| 只有这里有精品99| 亚洲国产精品成人综合色| 极品少妇高潮喷水抽搐| 亚洲av国产av综合av卡| 一区二区三区免费毛片| 久久久久久久久中文| 色综合亚洲欧美另类图片| 美女被艹到高潮喷水动态| 床上黄色一级片| 免费人成在线观看视频色| 一边亲一边摸免费视频| 亚洲丝袜综合中文字幕| 综合色av麻豆| 国产精品99久久久久久久久| 国产av国产精品国产| 国产伦在线观看视频一区| 久久人人爽人人爽人人片va| 欧美成人午夜免费资源| 国内少妇人妻偷人精品xxx网站| 亚洲婷婷狠狠爱综合网| 欧美变态另类bdsm刘玥| 中文欧美无线码| 久久久色成人| 免费无遮挡裸体视频| 久久久精品94久久精品| 高清在线视频一区二区三区| av播播在线观看一区| 日韩 亚洲 欧美在线| 久久精品人妻少妇| 麻豆av噜噜一区二区三区| 亚洲自拍偷在线| 久久草成人影院| 国产一区二区在线观看日韩| 日日啪夜夜爽| 精品午夜福利在线看| 国产一区有黄有色的免费视频 | 久久久久久久大尺度免费视频| 国产不卡一卡二| 99久久人妻综合| 亚洲av男天堂| 大又大粗又爽又黄少妇毛片口| 国产成人91sexporn| 久久久久久久大尺度免费视频| 日日啪夜夜撸| 日本免费a在线| 日日摸夜夜添夜夜爱| 欧美成人午夜免费资源| 欧美日韩在线观看h| 久久草成人影院| 国产精品无大码| 啦啦啦啦在线视频资源| 午夜日本视频在线| 能在线免费观看的黄片| 亚洲av日韩在线播放| 久久久久九九精品影院| 亚洲av二区三区四区| 观看美女的网站| 日韩国内少妇激情av| 国产精品女同一区二区软件| 秋霞伦理黄片| 美女大奶头视频| 免费在线观看成人毛片| 成人毛片60女人毛片免费| 啦啦啦中文免费视频观看日本| 国产精品人妻久久久久久| av一本久久久久| 午夜免费男女啪啪视频观看| 国产成人精品婷婷| 老师上课跳d突然被开到最大视频| 亚洲美女视频黄频| 99久国产av精品| 男的添女的下面高潮视频| 亚洲婷婷狠狠爱综合网| 国内精品一区二区在线观看| av在线天堂中文字幕| 国产精品不卡视频一区二区| 亚洲内射少妇av| 十八禁国产超污无遮挡网站| 色综合亚洲欧美另类图片| 成人亚洲精品av一区二区| 国产精品福利在线免费观看| 国产淫片久久久久久久久| 你懂的网址亚洲精品在线观看| 日日干狠狠操夜夜爽| 小蜜桃在线观看免费完整版高清| 美女黄网站色视频| 欧美成人精品欧美一级黄| av播播在线观看一区| 非洲黑人性xxxx精品又粗又长| 男的添女的下面高潮视频| 51国产日韩欧美| 精品一区二区三区人妻视频| 欧美成人a在线观看| 国产伦在线观看视频一区| 中文精品一卡2卡3卡4更新| 丝袜喷水一区| 亚洲一级一片aⅴ在线观看| 欧美日韩亚洲高清精品| 亚洲激情五月婷婷啪啪| 性色avwww在线观看| 白带黄色成豆腐渣| 少妇裸体淫交视频免费看高清| 小蜜桃在线观看免费完整版高清| 亚洲国产欧美在线一区| 乱码一卡2卡4卡精品| 免费观看a级毛片全部| 国产亚洲一区二区精品| 日产精品乱码卡一卡2卡三| 久久人人爽人人片av| 国产极品天堂在线| 亚洲国产色片| 日韩一本色道免费dvd| 蜜桃亚洲精品一区二区三区| 我的女老师完整版在线观看| 国产探花在线观看一区二区| 在线观看美女被高潮喷水网站| 亚洲性久久影院| 插阴视频在线观看视频| 午夜福利网站1000一区二区三区| 国产乱来视频区| 国产真实伦视频高清在线观看| 伊人久久国产一区二区| 国产高清国产精品国产三级 | 亚洲精品456在线播放app| 亚洲怡红院男人天堂| 精品国内亚洲2022精品成人| 综合色丁香网| 国产精品久久久久久久电影| 欧美丝袜亚洲另类| 日韩中字成人| 夜夜爽夜夜爽视频| 亚洲av一区综合| 精品不卡国产一区二区三区| 午夜精品在线福利| 亚洲激情五月婷婷啪啪| 别揉我奶头 嗯啊视频| 97在线视频观看| 岛国毛片在线播放| 亚洲av免费高清在线观看| 日韩av在线免费看完整版不卡| 国产视频内射| 免费不卡的大黄色大毛片视频在线观看 | 99热网站在线观看| 少妇的逼水好多| 少妇猛男粗大的猛烈进出视频 | 久久久久久国产a免费观看| 国产一区二区三区综合在线观看 | 国产成人精品婷婷| 欧美激情国产日韩精品一区| 国产精品熟女久久久久浪| 老司机影院毛片| 国产精品久久久久久精品电影小说 | 人人妻人人看人人澡| 一个人免费在线观看电影| 免费看光身美女| 久久久久久久午夜电影| 午夜老司机福利剧场| 一个人看的www免费观看视频| 久久6这里有精品| 成人高潮视频无遮挡免费网站| 久久精品久久精品一区二区三区| 国产一区二区三区综合在线观看 | 51国产日韩欧美| 久久久午夜欧美精品| 国产精品国产三级国产专区5o| 久久99蜜桃精品久久| 国产精品熟女久久久久浪| 亚洲欧美精品专区久久| 黄色欧美视频在线观看| 久久6这里有精品| 精品人妻偷拍中文字幕| 免费看日本二区| 搡女人真爽免费视频火全软件| 乱码一卡2卡4卡精品| 一级片'在线观看视频| 亚洲丝袜综合中文字幕| 久久久久久久午夜电影| 人人妻人人看人人澡| 欧美一区二区亚洲| 在线播放无遮挡| 中国国产av一级| 国产午夜精品论理片| 搡老乐熟女国产| 91狼人影院| 国产高清有码在线观看视频| 成人亚洲精品一区在线观看 | 久久久久久久久久成人| 女人十人毛片免费观看3o分钟| 永久免费av网站大全| 久久久久久久国产电影| 久久精品综合一区二区三区| 美女脱内裤让男人舔精品视频| 免费看av在线观看网站| av又黄又爽大尺度在线免费看| 国产毛片a区久久久久| 午夜爱爱视频在线播放| 热99在线观看视频| 日韩成人伦理影院| 男插女下体视频免费在线播放| 日韩中字成人| 18+在线观看网站| 午夜免费激情av| 婷婷色综合大香蕉| av专区在线播放| 精品久久久精品久久久| 国产午夜精品久久久久久一区二区三区| 欧美97在线视频| 欧美zozozo另类| 国产精品国产三级专区第一集| 亚洲av成人精品一区久久| 91久久精品国产一区二区成人| 天天躁夜夜躁狠狠久久av| 伊人久久国产一区二区| 天美传媒精品一区二区| 天天躁夜夜躁狠狠久久av| 老女人水多毛片| 亚洲aⅴ乱码一区二区在线播放| 久久久午夜欧美精品| 精品久久久噜噜| 午夜福利视频精品| av播播在线观看一区| av专区在线播放| 男插女下体视频免费在线播放| 在线观看一区二区三区| 免费看不卡的av|