The synthesis and liquid crystalline behaviour of a series of alkyloxy biphenyls were described.These includes 4-alkyloxy-4 -hydroxy biphenyls,p-alkyloxy biphenyl meth acrylytes,and the polymer of p-ethoxy biphenyl me...The synthesis and liquid crystalline behaviour of a series of alkyloxy biphenyls were described.These includes 4-alkyloxy-4 -hydroxy biphenyls,p-alkyloxy biphenyl meth acrylytes,and the polymer of p-ethoxy biphenyl meth acrylate (PEBPMA).The effects of reaction conditions on the yields of products were investigated.The liquid crystalline behaviour of the products was characterized by DSC, polarizing microscopy..It was found that the PEBPMA showed smectic phase.展开更多
Poly(glycidyl methacrylates)(PGMA) was grafted from zinc oxide(ZnO) nanowires via surface-initiated atom transfer radical polymerization(SI-ATRP) technique.Firstly,the ZnO nanowires were synthesized by the one-pot hyd...Poly(glycidyl methacrylates)(PGMA) was grafted from zinc oxide(ZnO) nanowires via surface-initiated atom transfer radical polymerization(SI-ATRP) technique.Firstly,the ZnO nanowires were synthesized by the one-pot hydrothermal technique.Subsequently,the ZnO was functionalized with 3-aminopropyl triethoxysilane,which was converted to macroinitiator by the esterification of them with 2-bromopropionyl bromide.PGMA grafted ZnO nanowires(PGMA-ZnO) were then synthesized in an ATRP of the GMA with CuCl/2,2`-bipyridine as the catalyst system.Kinetics studies revealed an approximate linear increase in weight of polymer with reaction time,indicating that the polymerization process owned some "living" character.The structure and composition of PGMA-ZnO were characterized with scanning electron microscope(SEM),energy-dispersive X-ray(EDX) spectrometer,fourier transform infrared spectroscopy(FT-IR) and thermogravimetric analysis(TGA).展开更多
The dynamics of a series of poly(n-alkyl methacrylates) is investigated by means of ^(13)C spin-lattice relaxation experiments. The results show that the dynamics has the polymer property dependence.
Antibacterial adhesives are promising to inhibit biofilms and secondary caries. The objectives of this study were to synthesize and incorporate quaternary ammonium methacrylates into adhesives, and investigate the alk...Antibacterial adhesives are promising to inhibit biofilms and secondary caries. The objectives of this study were to synthesize and incorporate quaternary ammonium methacrylates into adhesives, and investigate the alkyl chain length effects on three-dimensional biofilms adherent on adhesives for the first time. Six quaternary ammonium methacrylates with chain lengths of 3, 6, 9, 12, 16 and 18 were synthesized and incorporated into Scotchbond Multi-Purpose. Streptococcus mutans bacteria were cultured on resin to form biofilms. Confocal laser scanning microscopy was used to measure biofilm thickness, live/dead volumes and live-bacteria percentage vs. distance from resin surface. Biofilm thickness was the greatest for Scotchbond control; it decreased with increasing chain length, reaching a minimum at chain length 16. Live-biofilm volume had a similar trend. Dead-biofilm volume increased with increasing chain length. The adhesive with chain length 9 had 37% live bacteria near resin surface, but close to 100% live bacteria in the biofilm top section. For chain length 16, there were nearly 0% live bacteria throughout the three-dimensional biofilm. In conclusion, strong antibacterial activity was achieved by adding quaternary ammonium into adhesive, with biofilm thickness and live-biofilm volume decreasing as chain length was increased from 3 to 16. Antibacterial adhesives typically only inhibited bacteria close to its surface; however, adhesive with chain length 16 had mostly dead bacteria in the entire three-dimensional biofilm. Antibacterial adhesive with chain length 16 is promising to inhibit biofilms at the margins and combat secondary caries.展开更多
Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have b...Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been realized.The P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were synthesized.In the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy groups.The pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)SH.The thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.展开更多
Acrylamide was introduced onto the chain of poly[oligo(oxyethylene) methacrylate] as a polar constituent, and the effect of its presence on the mechanical strength and ionic conduction properties of Li-salt complex ba...Acrylamide was introduced onto the chain of poly[oligo(oxyethylene) methacrylate] as a polar constituent, and the effect of its presence on the mechanical strength and ionic conduction properties of Li-salt complex based on the resultant copolymer was investigated. The introduction of the polar constituent raises chain rigidity, retards crystallization of oligo(oxyethylene) domain and promotes the dissociation of lithium salt. The factors work on the mechanical and conduction properties synergistically, therefore both of the properties are improved simultaneously as the consequence of acrylamide-introduction.展开更多
Films were prepared from mixtures of copolymers of 4-nitro-4'-[N-methylacryloyloxyethyl, N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) and copolymers containing anhydride ...Films were prepared from mixtures of copolymers of 4-nitro-4'-[N-methylacryloyloxyethyl, N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) and copolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophore content: 25 mol %). During thermal poling process the anhydride reacts with the epoxy group and the resulting crosslinked network structure will stabilize the second harmonic generation in the poled film. The second harmonic generation of the poled film shows a maximum with the variation of composition this is presumed to be due to the effects of the increasing of concentration, orientation order as well as orientation stability of chromophore groups during crosslinking.展开更多
Anionic polymerization of methyl methacrylate (MMA), n-butyl methacrylate (nBMA) and glycidyl methacrylate (GMA) initiated by nBuCu(NCy2)Li (1) in tetrahydrofuran (THF) at -50 degrees C to -10 degrees C was investigat...Anionic polymerization of methyl methacrylate (MMA), n-butyl methacrylate (nBMA) and glycidyl methacrylate (GMA) initiated by nBuCu(NCy2)Li (1) in tetrahydrofuran (THF) at -50 degrees C to -10 degrees C was investigated. It was found that the polymerization of MMA and nBMA initiated by 1 proceeded quantitatively in THF to afford PMMA and PBMA with polydispersity index 1.15-1.30 and nearly 100% initiator efficiencies at -10 degrees C. The molecular weights increased linearly with the ratio of [monomer]/[1]. However, a post-polymerization experiment carried out on this system revealed a double polymer peak by GPC when fresh monomer was added after an interval of 10 min. Polymerization of styrene could be initiated by 1, but the initiator efficiency was low.展开更多
Ringlike polar monomer maleic, anhydride (MAn) was copolymerized with oligo (oxyethylene) methacrylate (MEO_n), and its effect on ion conduction property of the corresponding polymer-salt complexes was studied. As a c...Ringlike polar monomer maleic, anhydride (MAn) was copolymerized with oligo (oxyethylene) methacrylate (MEO_n), and its effect on ion conduction property of the corresponding polymer-salt complexes was studied. As a consequence the introduction of MAn onto polymer chain retards crystallization of the ether pendants considerably, and improves the ion conductivity to a larger degree compared with other polar groups once investigated (σ_(max),25℃=8.5×10^(-5) S/cm). The structure-ion conduction relation in the polymer-salt matrix is also analyzed macroscopically through the correspondence between composition-dependences of polymerization conversion and isothermal ion conductivity, and microscopically through the measurements of cross polarized light and electron transmission.展开更多
Synthesis and anionic polymerization of the fluorine-substituted phenyl methacrylates are herein reported. A series of monodi-, and multi-substituted fluorophenyl methacrylates H2C=C（CH3）C（O）OC6H4F-4 （M^1a）, H2...Synthesis and anionic polymerization of the fluorine-substituted phenyl methacrylates are herein reported. A series of monodi-, and multi-substituted fluorophenyl methacrylates H2C=C（CH3）C（O）OC6H4F-4 （M^1a）, H2C=C（CH3）C（O）OC6H4F-3 （M^1b）, HEC=C（CH3）C（O）OC6H3F2-2,4 （M^2）, H2C=C（CH3）C（O）OC6H2F3-2,3,4 （M^3）, H2C=C（CH3）C（O）OC6HF4-2,3,5,6 （M^4）, and H2C=C（CH3）C（O）OC6F5 （M^5） were synthesized and characterized. Initially, the polymerization was carded out on the monomer M^1a by using nBuLi, tBuLi, and KH as the respective catalysts; this approach produced the polymers in yields of 12%-50%, but with lower molecular weights. Similar results were obtained by using tBuLi for catalytically polymerizing the other five monomers. By introducing a co-catalyst MeAl（BHT）2, the catalysts Nail, LiH, and tBuOLi each were tested to polymerize M^1a, which gave the polymers in very low yields （3%-7%）. Polymer yields of 13%-27% were obtained by each of the catalysts LiAlH4, nBuLi, PhLi, and tBuLi in connection with MeAI（BHT）2, but a better yield （61%） was achieved with KH/MeAl（BHT）2. The KH/MeAl（BHT）2 catalyst system was further employed to polymerize M^1b and M^2, which afforded respective polymer yields of 12%-63% and 10%-53%, depending on the molar ratios of KH：MeAl（BHT）2 as well as on the monomer concentrations. All of the polymers produced were syndiotactically rich in structure, as indicated by either ^1H or ^19F NMR data. The polymerization mechanism by the combined catalyst system is proposed.展开更多
Treating bone defects complicated by bacterial infections remains a significant clinical challenge.Drawing inspiration from the human body's bone repair mechanisms,the use of biomimetic methods to design tissue en...Treating bone defects complicated by bacterial infections remains a significant clinical challenge.Drawing inspiration from the human body's bone repair mechanisms,the use of biomimetic methods to design tissue engineering scaffolds is of great significance for bone repair.This study synthesized copper(Cu)-doped mesoporous silica nanoparticles(Cu@MSN)modified with hydroxyethyl methacrylate to obtain methacrylated Cu@MSN(Cu@MSNMA).Furtheremore,bio-mimetic nanocomposite hydrogels were prepared by adding Cu@MSNMA to a GelMA/gelatin solution.This hydrogel achieves multi-modal bone tissue biomimicry:(ⅰ)GelMA/gelatin mimics the matrix components in bone ECM,ensuring biocompatibility while promoting cellular behavior(such as adhesion,proliferation,and differentiation);(ⅱ)GelMA/gela-tin and the crosslinking sites introduced by Cu@MSNMA form a stable porous network structure,achieving structural and mechanical biomimicry to provide necessary support for bone defects;(ⅲ)The elemental biomimicry of Si and Cu in Cu@MSNMA achieves efficient osteogenic induction.The effect of different proportions of Cu@MSNMA on the physi-cal properties of the composite hydrogels was investigated to determine the optimal proportion.The results indicated that the mechanical properties of hydrogel were enhanced with the increasing Cu@MSNMA mass ratio.Notably,5%NPs/GelMA/gelatin hydrogel exhibited excellent mechanical property compared to the GelMA/gelatin hydrogel.In vitro and vivo cellular experiments demonstrated a significant enhancement in antibacterial and osteogenic induction with Cu@MSNMA addition.In conclusion,the proposed nanocomposite hydrogel with biomimetic components and ion-regulating properties can serve as a multifunctional scaffold,offering antimicrobial properties for infected bone regeneration,and guide for future research in bone regeneration and three-dimensional printing.展开更多
In this paper,low-temperature dielectric-blocked discharge plasma(DBD)was employed for the first time to treat silica-doped H_(4)PMo_(11)VO_(40)(HPAV)catalysts(DBD(Ar/x)-MF-Catal)and apply them in the catalytic methac...In this paper,low-temperature dielectric-blocked discharge plasma(DBD)was employed for the first time to treat silica-doped H_(4)PMo_(11)VO_(40)(HPAV)catalysts(DBD(Ar/x)-MF-Catal)and apply them in the catalytic methacrolein(MAL)selective oxidation to produce methacrylic acid(MAA).This work investigates in detail the controllable regulation of the concentration of oxidation states on silica-doped HPAV catalysts by adjusting the DBD discharge with controlled changes in voltage,current,treatment time,and treatment medium.It reports the intrinsic correlation between oxidation states and MAL oxidation performance.The research results indicated that the catalytic performance was related to the presence of oxygen vacancies and oxygen species(VO^(2+)),and are the main reason for the selective oxidation of MAL to MAA.Besides,the generation of oxygen vacancies and VO^(2+)altered localized electrons,which resulted in the easier activation of O_(2).Theoretical calculations of DFT also proved the formation mechanism of oxygen vacancies and VO^(2+)and electron properties on high-performance polymers,which elucidated the intrinsic influence of catalyst components.The DBD(Ar/10)-MF-Catal catalysts with suitable VO^(2+)and oxygen vacancy concentrations exhibited the highest catalytic performance with 90%MAL conversion and 70%MAA selectivity and showed good stability(500 h).展开更多
Oral ulcers may greatly diminish patient life quality and potentially result in malignant transformations.Using gels or films as pseudomembrane barriers is an effective method for promoting ulcer healing.However,these...Oral ulcers may greatly diminish patient life quality and potentially result in malignant transformations.Using gels or films as pseudomembrane barriers is an effective method for promoting ulcer healing.However,these pseudomembranes face challenges such as saliva flushing,dynamic changes,and the presence of abundant microorganisms in the complex oral environment.Herein,we developed an injectable,photoinduction,in situ-enhanceable oral ulcer repair hydrogel(named as GIL2)by incorporating dynamic phenylboronic acid ester bonds and imidazole ions into a methacrylated gelatin matrix.GIL2 exhibited rapid gelation(3 s),low swelling properties(1.07 g/g),robust tensile strength(56.83 kPa)and high adhesive strength(63.38 kPa),allowing it to adhere effectively to the ulcer surface.Moreover,the GIL2 demonstrated intrinsic antibacterial and antioxidant qualities.Within a diabetic rat model for oral ulcers,GIL2 effectively eased oxidative stress and decreased the inflammation present in ulcerated wounds,thereby greatly hastening the healing process of these ulcers.Together,GIL2 hydrogel demonstrates remarkable adaptability within the oral milieu,revitalizing clinical strategy advancements for treating bacterialinfected oral ulcers.展开更多
Traditional biodiesel production primarily uses methanol as the acyl acceptor,but its toxicity to lipase increases process complexity and operational difficulty elevate manufacturing costs.This study aimed to explore ...Traditional biodiesel production primarily uses methanol as the acyl acceptor,but its toxicity to lipase increases process complexity and operational difficulty elevate manufacturing costs.This study aimed to explore a new method for enzymatic synthesis of biodiesel with methyl methacrylate(MMA)as acyl acceptor.Meanwhile,a 1,3-position specific lipase Lipozyme RM IM was applied as biocatalyst,which enables simultaneous production of biodiesel(FAMEs)and methacrylate fatty acid glycerides(MFAGs)via specific sn-1,3 transesterification of MMA with triglyceride.Under the optimal reaction conditions:temperature of 50℃,molar ratio of 4:1 for MMA to triglyceride,enzyme dosage of 7.5%(mass),and an extra water addition of 0.5%(mass);triglyceride conversion rate of 97%,and FAMEs yield of 65%could be obtained.Simultaneously,the multistage short-path distillation and column chromatographic method were combined used for the separation of the mixed products.Finally,the purity of FAME,MFADG,DMFAG,and MMFAG were 98%,97.8%,95.3%,and 81.78%,respectively.In this new approach,MMA demonstrates lower toxicity to lipases,allowing for straightfo rward addition of all the substrates without complex addition process,and enhancing operational feasibility.Meanwhile,the by-products of MFAGs could be applied as monomers in varnishes and protective coatings,which increased the value of the products.Thus,this investigation providing an alternative way to produce biodiesel,and providing a new pathway for the sustainable development of biodiesel.展开更多
Compatibilization is crucial for the blending of immiscible polymers to develop high-performance composites;however,traditional compatibilization by copolymers(pre-made or in-situ generation)suffers from weak interfac...Compatibilization is crucial for the blending of immiscible polymers to develop high-performance composites;however,traditional compatibilization by copolymers(pre-made or in-situ generation)suffers from weak interface anchoring,and inorganic particles have gained extensive attention recently owing to their large interfacial desorption energy,while their low affinity to bulk components is a drawback.In this study,an interfacial atom transfer radical polymerization(ATRP)technique was employed to grow polystyrene(PS)and poly(2-hydroxyethyl methacrylate)(PHEMA)simultaneously on different hemispheres of Br-functionalized SiO_(2) nanoparticles to stabilize a Pickering emulsion,whereby a brush-type Janus nanoparticle(SiO_(2)@JNP)was developed.The polymer brushes were well-characterized,and the Janus feature was validated by transmission electron microscope(TEM)observation of the sole hemisphere grafting of SiO_(2)-PS as a control sample.SiO_(2)@JNP was demonstrated to be an efficient compatibilizer for a PS/poly(methyl methacrylate)(PMMA)immiscible blend,and the droplet-matrix morphology was significantly refined.The mechanical strength and toughness of the blend were synchronously enhanced at a low content SiO_(2)@JNP optimized~0.9 wt%,with the tensile strength,elongation at break and impact strength increased by 17.7%,26.6%and 19.6%,respectively.This enhancement may be attributed to the entanglements between the grafted polymer brushes and individual components that improve the particle-bulk phase affinity and enforce interfacial adhesion.展开更多
The purpose of this study is to develop novel P-Mo-V heteropoly compound catalysts for the oxidation of methacrolein to methacrylic acid.The introduction of Cu,as a modifying element,was employed to enhance the cataly...The purpose of this study is to develop novel P-Mo-V heteropoly compound catalysts for the oxidation of methacrolein to methacrylic acid.The introduction of Cu,as a modifying element,was employed to enhance the catalytic performance.Experimental results show that the addition of Cu significantly improved the catalyst performance,increasing the conversion rate of methacrolein from 17.2%to 84.2%,while the yield of methacrylic acid was boosted from 5.5%to 51.7%.A series of characterization results showed that both P-Mo-V and Cu-P-Mo-V catalysts primarily exhibited the crystal phase of[PMo_(12)O_(40)]^(3−),with a small amount of[PMo_(11)VO_(40)]^(3−)phase.However,the Cu-P-Mo-V catalyst exhibited much better oxidation–reduction ability compared to the P-Mo-V catalyst.Isolated Cu atoms were found to exist in a highly decentralized tetrahedral coordination structure,bridged by oxygen atoms within the heteropoly compound framework.The addition of Cu resulted in notable alterations in the modulation of the surface electronic structure,enhancement of oxidation–reduction ability,and optimization of the reaction pathway,thereby improving the overall catalytic activity of the catalyst.This study not only provides new insights into the modification of P-Mo-V heteropoly compound catalysts but also lays a foundation for understanding their catalytic mechanisms in organic synthesis reactions,demonstrating the potential of modifying elements in improving catalyst performance.展开更多
Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,...Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,the migration behavior of temporary plugging agent(TPA),as a function of the concentration and particle size of TPA and cluster-perforation numbers,etc.,determining the effectiveness of this technique,remains unclear.Therefore,this study conducted innovatively a series of TPDF simulation experiments on transparent polymethyl methacrylate(PMMA)specimens(cubic block of 30 cm×30 cm×30 cm)to explore visually the migration behavior of TPA in multi-clustered HFs in a horizontal well.A laboratory hydraulic sandblasting perforation completion technique was implemented to simulate the multi-cluster perforations.All the distributions of wellbore,perforations,HFs,and TPA can be seen clearly inside the PMMA specimen post the experiment.The results show that there are four characteristic plugging positions for the TPA:mouth of HF,middle of HF,tip of HF,and the intersection of HFs.Small particle size TPA tends to migrate to the fracture tip for plugging,while large particle size TPA tends to plug at the fracture mouth.The migration of the TPA is influenced obviously by the morphology of the fracture wall.A smooth fracture wall is conducive to the migration of the TPA to the far end of HFs,but not conducive to generating the plugging zone and HF diversion.In contrast,a"leaf vein"fracture of rough wall is conducive to generating the plugging layer and the diversion of HFs,but not conducive to the migration of the TPA to the far end of HFs.The migration ability of TPA in a"shell"pattern is intermediate between the two above cases.Increasing TPA concentration can encourage TPA to migrate more quickly to the characteristic plugging position,and thereby to promote the creation of effective plugging and subsequently the multi-stage diversion of the HFs.Nevertheless,excessive concentration may cause the TPA to settle prematurely,affecting the propagation of the HFs to the far end.Increasing the number of clusters to a certain extent can encourage TPA to migrate into the HFs and form plugging,and promote the diversion.An evaluation system for the migration ability of granular TPA has been established,and it was calculated that when there is no plugging expectation target,the comprehensive migration ability of small particle size TPA is stronger than that of large particle size TPA.This research provides theoretical foundation for the optimization of temporary plugging parameters.展开更多
The rapid development of nanotechnology has significantly revolutionized wearable electronics and expanded their functionality.Through introducing innovative solutions for energy harvesting and autonomous sensing,this...The rapid development of nanotechnology has significantly revolutionized wearable electronics and expanded their functionality.Through introducing innovative solutions for energy harvesting and autonomous sensing,this research presents a cost-effective strategy to enhance the performance of triboelectric nanogenerators(TENGs).The TENG was fabricated from polyvinylidene fluoride(PVDF)and N,N'-poly(methyl methacrylate)(PMMA)blend with a porous structure via a novel optimized quenching method.The developed approach results in a highβ-phase content(85.7%)PVDF/3wt.%PMMA porous blend,known for its superior piezoelectric properties.PVDF/3wt.%PMMA modified porous TENG demonstrates remarkable electrical output,with a dielectric constant of 40 and an open-circuit voltage of approximately 600 V.The porous matrix notably increases durability,enduring over 36000 operational cycles without performance degradation.Moreover,practical applications were explored in this research,including powering LEDs and pacemakers with a maximum power output of 750mWm^(-2).Also,TENG served as a self-powered tactile sensor for robotic applications in various temperature conditions.The work highlights the potential of the PVDF/PMMA porous blend to utilize the next-generation self-powered sensors and power small electronic devices.展开更多
Drilling and blasting,characterized by their efficiency,ubiquity,and cost-effectiveness,have emerged as predominant techniques in rock excavation;however,they are accompanied by enormous destructive power.Accurately c...Drilling and blasting,characterized by their efficiency,ubiquity,and cost-effectiveness,have emerged as predominant techniques in rock excavation;however,they are accompanied by enormous destructive power.Accurately controlling the blasting energy and achieving the directional fracture of a rock mass have become common problems in the field.A two-dimensional blasting(2D blasting)technique was proposed that utilizes the characteristic that the tensile strength of a rock mass is significantly lower than its compressive strength.After blasting,only a 2D crack surface is generated along the predetermined direction,eliminating the damage to the reserved rock mass caused by conventional blasting.However,the interior of a natural rock mass is a"black box",and the process of crack propagation is difficult to capture,resulting in an unclear 2D blasting mechanism.To this end,a single-hole polymethyl methacrylate(PMMA)test piece was used to conduct a 2D blasting experiment with the help of a high-speed camera to capture the dynamic crack propagation process and the digital image correlation(DIC)method to analyze the evolution law of surface strain on the test piece.On this basis,a three-dimensional(3D)finite element model was established based on the progressive failure theory to simulate the stress,strain,damage,and displacement evolution process of the model under 2D blasting.The simulation results were consistent with the experimental results.The research results reveal the 2D blasting mechanism and provide theoretical support for the application of 2D blasting technology in the field of rock excavation.展开更多
Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited p...Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited pH dependant swelling and solute diffusivity due to the formation or disruption of hydrogen bonded complexation between methacrylic acid (MAA) and etheric (EO). In neutral and basic conditions (above the swelling transition pH), the copolymer swelling was greatly higher than acid condition. In complexed hydrogels, the diffusion coefficients of vitamin B12 (VB12) were in the range of 10-10 to 10-7 cm2s-1; While in uncomplexed hydrogels, the values were about 210-6 cm2s-1. The comonomer composition and synthesis conditions have great effect on the structure, and thereby, swelling and solute diffusion characteristics of the resultant hydrogels. For the copolymers with composition of less than or more than 1:1 MAA/EO molar ratio, the plot of lnD vs 1/H-1 followed two different linear equations of 慺ree volume theory? respectively.展开更多
文摘The synthesis and liquid crystalline behaviour of a series of alkyloxy biphenyls were described.These includes 4-alkyloxy-4 -hydroxy biphenyls,p-alkyloxy biphenyl meth acrylytes,and the polymer of p-ethoxy biphenyl meth acrylate (PEBPMA).The effects of reaction conditions on the yields of products were investigated.The liquid crystalline behaviour of the products was characterized by DSC, polarizing microscopy..It was found that the PEBPMA showed smectic phase.
基金the National Natural Science Foundation of China (No.50730008 and 30772434)Shanghai Science & Technology Committee (No.09JC1407400 and 1052nm02000)
文摘Poly(glycidyl methacrylates)(PGMA) was grafted from zinc oxide(ZnO) nanowires via surface-initiated atom transfer radical polymerization(SI-ATRP) technique.Firstly,the ZnO nanowires were synthesized by the one-pot hydrothermal technique.Subsequently,the ZnO was functionalized with 3-aminopropyl triethoxysilane,which was converted to macroinitiator by the esterification of them with 2-bromopropionyl bromide.PGMA grafted ZnO nanowires(PGMA-ZnO) were then synthesized in an ATRP of the GMA with CuCl/2,2`-bipyridine as the catalyst system.Kinetics studies revealed an approximate linear increase in weight of polymer with reaction time,indicating that the polymerization process owned some "living" character.The structure and composition of PGMA-ZnO were characterized with scanning electron microscope(SEM),energy-dispersive X-ray(EDX) spectrometer,fourier transform infrared spectroscopy(FT-IR) and thermogravimetric analysis(TGA).
基金Supported by The National Natural Science Foundation of China
文摘The dynamics of a series of poly(n-alkyl methacrylates) is investigated by means of ^(13)C spin-lattice relaxation experiments. The results show that the dynamics has the polymer property dependence.
基金supported by NIH R01 DE17974West China School of Stomatologya Seed Grant from Department of Endodontics,Prosthodontics and Operative Dentistry,University of Maryland
文摘Antibacterial adhesives are promising to inhibit biofilms and secondary caries. The objectives of this study were to synthesize and incorporate quaternary ammonium methacrylates into adhesives, and investigate the alkyl chain length effects on three-dimensional biofilms adherent on adhesives for the first time. Six quaternary ammonium methacrylates with chain lengths of 3, 6, 9, 12, 16 and 18 were synthesized and incorporated into Scotchbond Multi-Purpose. Streptococcus mutans bacteria were cultured on resin to form biofilms. Confocal laser scanning microscopy was used to measure biofilm thickness, live/dead volumes and live-bacteria percentage vs. distance from resin surface. Biofilm thickness was the greatest for Scotchbond control; it decreased with increasing chain length, reaching a minimum at chain length 16. Live-biofilm volume had a similar trend. Dead-biofilm volume increased with increasing chain length. The adhesive with chain length 9 had 37% live bacteria near resin surface, but close to 100% live bacteria in the biofilm top section. For chain length 16, there were nearly 0% live bacteria throughout the three-dimensional biofilm. In conclusion, strong antibacterial activity was achieved by adding quaternary ammonium into adhesive, with biofilm thickness and live-biofilm volume decreasing as chain length was increased from 3 to 16. Antibacterial adhesives typically only inhibited bacteria close to its surface; however, adhesive with chain length 16 had mostly dead bacteria in the entire three-dimensional biofilm. Antibacterial adhesive with chain length 16 is promising to inhibit biofilms at the margins and combat secondary caries.
基金financially supported by the National Natural Science Foundation of China (Nos. 21972112 and 22225104)China Postdoctoral Science Foundation (Nos. 2022TQ0115 and 2022M711297)。
文摘Chemoselective,living/controlled polymerizations of allyl methacrylate(AMA) and vinyl methacrylate(VMA) with/without methyl methacrylate(MMA) by using the phosphonium ylide/organoaluminum based Lewis pairs(LPs) have been realized.The P-ylide-2/AIMe(BHT)_(2)(Pylide-2=Ph_(3)P=CHMe and BHT=2,6-iBu_(2)-4-MeC_(6)H_(2)O) was demonstrated to be superior by which homopolymers PAMAs(M_(n)=27.6-111.5kg/mol and ■=1.14-1.25) and PVMAs(M_(n)=28.4-78.4 kg/mol and ■=1.12-1.18) and block copolymers PMMA-b-PAMA,PAMA-b-PVMA,PAMA-bPMMA,PMMA-b-PAMA-b-PMMA,PAMA-b-PMMA-b-PAMA,and PAMA-b-PVMA-b-PAMA were synthesized.In the polymerizations,all of the monomers were reacted by the conjugated ester vinyl groups leaving intactly the nonconjugated acryloxy groups.The pendant acryloxy groups attached to the main chain enable further to post-functionalization by the AIBN-induced radical "thiol-ene" reaction using PhCH_(2)SH.The thiolether side group-containing polymers PAMA-SCH_(2)Ph and PAMA-SCH_(2)Ph-b-PMMA-b-PAMA-SCH_(2)Ph were thus prepared.
文摘Acrylamide was introduced onto the chain of poly[oligo(oxyethylene) methacrylate] as a polar constituent, and the effect of its presence on the mechanical strength and ionic conduction properties of Li-salt complex based on the resultant copolymer was investigated. The introduction of the polar constituent raises chain rigidity, retards crystallization of oligo(oxyethylene) domain and promotes the dissociation of lithium salt. The factors work on the mechanical and conduction properties synergistically, therefore both of the properties are improved simultaneously as the consequence of acrylamide-introduction.
文摘Films were prepared from mixtures of copolymers of 4-nitro-4'-[N-methylacryloyloxyethyl, N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) and copolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophore content: 25 mol %). During thermal poling process the anhydride reacts with the epoxy group and the resulting crosslinked network structure will stabilize the second harmonic generation in the poled film. The second harmonic generation of the poled film shows a maximum with the variation of composition this is presumed to be due to the effects of the increasing of concentration, orientation order as well as orientation stability of chromophore groups during crosslinking.
基金supported by the National Natural Science Foundation of China(No.20374005)China Petroleum &Chemical Corporation.
文摘Anionic polymerization of methyl methacrylate (MMA), n-butyl methacrylate (nBMA) and glycidyl methacrylate (GMA) initiated by nBuCu(NCy2)Li (1) in tetrahydrofuran (THF) at -50 degrees C to -10 degrees C was investigated. It was found that the polymerization of MMA and nBMA initiated by 1 proceeded quantitatively in THF to afford PMMA and PBMA with polydispersity index 1.15-1.30 and nearly 100% initiator efficiencies at -10 degrees C. The molecular weights increased linearly with the ratio of [monomer]/[1]. However, a post-polymerization experiment carried out on this system revealed a double polymer peak by GPC when fresh monomer was added after an interval of 10 min. Polymerization of styrene could be initiated by 1, but the initiator efficiency was low.
文摘Ringlike polar monomer maleic, anhydride (MAn) was copolymerized with oligo (oxyethylene) methacrylate (MEO_n), and its effect on ion conduction property of the corresponding polymer-salt complexes was studied. As a consequence the introduction of MAn onto polymer chain retards crystallization of the ether pendants considerably, and improves the ion conductivity to a larger degree compared with other polar groups once investigated (σ_(max),25℃=8.5×10^(-5) S/cm). The structure-ion conduction relation in the polymer-salt matrix is also analyzed macroscopically through the correspondence between composition-dependences of polymerization conversion and isothermal ion conductivity, and microscopically through the measurements of cross polarized light and electron transmission.
基金supported by the National Basic Research Program of China(2012CB821704)the National Natural Science Foundation of China(20972129)the Innovative Research Team Program(IRT1036,J1310024)
文摘Synthesis and anionic polymerization of the fluorine-substituted phenyl methacrylates are herein reported. A series of monodi-, and multi-substituted fluorophenyl methacrylates H2C=C（CH3）C（O）OC6H4F-4 （M^1a）, H2C=C（CH3）C（O）OC6H4F-3 （M^1b）, HEC=C（CH3）C（O）OC6H3F2-2,4 （M^2）, H2C=C（CH3）C（O）OC6H2F3-2,3,4 （M^3）, H2C=C（CH3）C（O）OC6HF4-2,3,5,6 （M^4）, and H2C=C（CH3）C（O）OC6F5 （M^5） were synthesized and characterized. Initially, the polymerization was carded out on the monomer M^1a by using nBuLi, tBuLi, and KH as the respective catalysts; this approach produced the polymers in yields of 12%-50%, but with lower molecular weights. Similar results were obtained by using tBuLi for catalytically polymerizing the other five monomers. By introducing a co-catalyst MeAl（BHT）2, the catalysts Nail, LiH, and tBuOLi each were tested to polymerize M^1a, which gave the polymers in very low yields （3%-7%）. Polymer yields of 13%-27% were obtained by each of the catalysts LiAlH4, nBuLi, PhLi, and tBuLi in connection with MeAI（BHT）2, but a better yield （61%） was achieved with KH/MeAl（BHT）2. The KH/MeAl（BHT）2 catalyst system was further employed to polymerize M^1b and M^2, which afforded respective polymer yields of 12%-63% and 10%-53%, depending on the molar ratios of KH：MeAl（BHT）2 as well as on the monomer concentrations. All of the polymers produced were syndiotactically rich in structure, as indicated by either ^1H or ^19F NMR data. The polymerization mechanism by the combined catalyst system is proposed.
基金National Key R&D Program of China(grant number 2022YFA1207500)National Natural Science Foundation of China(grant number 82072412).
文摘Treating bone defects complicated by bacterial infections remains a significant clinical challenge.Drawing inspiration from the human body's bone repair mechanisms,the use of biomimetic methods to design tissue engineering scaffolds is of great significance for bone repair.This study synthesized copper(Cu)-doped mesoporous silica nanoparticles(Cu@MSN)modified with hydroxyethyl methacrylate to obtain methacrylated Cu@MSN(Cu@MSNMA).Furtheremore,bio-mimetic nanocomposite hydrogels were prepared by adding Cu@MSNMA to a GelMA/gelatin solution.This hydrogel achieves multi-modal bone tissue biomimicry:(ⅰ)GelMA/gelatin mimics the matrix components in bone ECM,ensuring biocompatibility while promoting cellular behavior(such as adhesion,proliferation,and differentiation);(ⅱ)GelMA/gela-tin and the crosslinking sites introduced by Cu@MSNMA form a stable porous network structure,achieving structural and mechanical biomimicry to provide necessary support for bone defects;(ⅲ)The elemental biomimicry of Si and Cu in Cu@MSNMA achieves efficient osteogenic induction.The effect of different proportions of Cu@MSNMA on the physi-cal properties of the composite hydrogels was investigated to determine the optimal proportion.The results indicated that the mechanical properties of hydrogel were enhanced with the increasing Cu@MSNMA mass ratio.Notably,5%NPs/GelMA/gelatin hydrogel exhibited excellent mechanical property compared to the GelMA/gelatin hydrogel.In vitro and vivo cellular experiments demonstrated a significant enhancement in antibacterial and osteogenic induction with Cu@MSNMA addition.In conclusion,the proposed nanocomposite hydrogel with biomimetic components and ion-regulating properties can serve as a multifunctional scaffold,offering antimicrobial properties for infected bone regeneration,and guide for future research in bone regeneration and three-dimensional printing.
基金financially supported by the Taishan Scholars Program of Shandong Province(No.tsqn202103051)the Science and Technology Project of Xinjiang Bingtuan Supported by the Central Government(No.2022BC001)the Project of Scientific Research in Shihezi University(No.CXFZ202205)。
文摘In this paper,low-temperature dielectric-blocked discharge plasma(DBD)was employed for the first time to treat silica-doped H_(4)PMo_(11)VO_(40)(HPAV)catalysts(DBD(Ar/x)-MF-Catal)and apply them in the catalytic methacrolein(MAL)selective oxidation to produce methacrylic acid(MAA).This work investigates in detail the controllable regulation of the concentration of oxidation states on silica-doped HPAV catalysts by adjusting the DBD discharge with controlled changes in voltage,current,treatment time,and treatment medium.It reports the intrinsic correlation between oxidation states and MAL oxidation performance.The research results indicated that the catalytic performance was related to the presence of oxygen vacancies and oxygen species(VO^(2+)),and are the main reason for the selective oxidation of MAL to MAA.Besides,the generation of oxygen vacancies and VO^(2+)altered localized electrons,which resulted in the easier activation of O_(2).Theoretical calculations of DFT also proved the formation mechanism of oxygen vacancies and VO^(2+)and electron properties on high-performance polymers,which elucidated the intrinsic influence of catalyst components.The DBD(Ar/10)-MF-Catal catalysts with suitable VO^(2+)and oxygen vacancy concentrations exhibited the highest catalytic performance with 90%MAL conversion and 70%MAA selectivity and showed good stability(500 h).
基金funding from the National Natural Science Foundation of China(Nos.82071170 and 82371016)the Zhejiang Provincial Science and Technology Project for Public Welfare(No.LGF21H140004).
文摘Oral ulcers may greatly diminish patient life quality and potentially result in malignant transformations.Using gels or films as pseudomembrane barriers is an effective method for promoting ulcer healing.However,these pseudomembranes face challenges such as saliva flushing,dynamic changes,and the presence of abundant microorganisms in the complex oral environment.Herein,we developed an injectable,photoinduction,in situ-enhanceable oral ulcer repair hydrogel(named as GIL2)by incorporating dynamic phenylboronic acid ester bonds and imidazole ions into a methacrylated gelatin matrix.GIL2 exhibited rapid gelation(3 s),low swelling properties(1.07 g/g),robust tensile strength(56.83 kPa)and high adhesive strength(63.38 kPa),allowing it to adhere effectively to the ulcer surface.Moreover,the GIL2 demonstrated intrinsic antibacterial and antioxidant qualities.Within a diabetic rat model for oral ulcers,GIL2 effectively eased oxidative stress and decreased the inflammation present in ulcerated wounds,thereby greatly hastening the healing process of these ulcers.Together,GIL2 hydrogel demonstrates remarkable adaptability within the oral milieu,revitalizing clinical strategy advancements for treating bacterialinfected oral ulcers.
文摘Traditional biodiesel production primarily uses methanol as the acyl acceptor,but its toxicity to lipase increases process complexity and operational difficulty elevate manufacturing costs.This study aimed to explore a new method for enzymatic synthesis of biodiesel with methyl methacrylate(MMA)as acyl acceptor.Meanwhile,a 1,3-position specific lipase Lipozyme RM IM was applied as biocatalyst,which enables simultaneous production of biodiesel(FAMEs)and methacrylate fatty acid glycerides(MFAGs)via specific sn-1,3 transesterification of MMA with triglyceride.Under the optimal reaction conditions:temperature of 50℃,molar ratio of 4:1 for MMA to triglyceride,enzyme dosage of 7.5%(mass),and an extra water addition of 0.5%(mass);triglyceride conversion rate of 97%,and FAMEs yield of 65%could be obtained.Simultaneously,the multistage short-path distillation and column chromatographic method were combined used for the separation of the mixed products.Finally,the purity of FAME,MFADG,DMFAG,and MMFAG were 98%,97.8%,95.3%,and 81.78%,respectively.In this new approach,MMA demonstrates lower toxicity to lipases,allowing for straightfo rward addition of all the substrates without complex addition process,and enhancing operational feasibility.Meanwhile,the by-products of MFAGs could be applied as monomers in varnishes and protective coatings,which increased the value of the products.Thus,this investigation providing an alternative way to produce biodiesel,and providing a new pathway for the sustainable development of biodiesel.
基金financially supported by the National Natural Science Foundation of China(Nos.22172028,21903015,and 22403017)Natural Science Foundation of Fujian Province of China(No.2022J05041)。
文摘Compatibilization is crucial for the blending of immiscible polymers to develop high-performance composites;however,traditional compatibilization by copolymers(pre-made or in-situ generation)suffers from weak interface anchoring,and inorganic particles have gained extensive attention recently owing to their large interfacial desorption energy,while their low affinity to bulk components is a drawback.In this study,an interfacial atom transfer radical polymerization(ATRP)technique was employed to grow polystyrene(PS)and poly(2-hydroxyethyl methacrylate)(PHEMA)simultaneously on different hemispheres of Br-functionalized SiO_(2) nanoparticles to stabilize a Pickering emulsion,whereby a brush-type Janus nanoparticle(SiO_(2)@JNP)was developed.The polymer brushes were well-characterized,and the Janus feature was validated by transmission electron microscope(TEM)observation of the sole hemisphere grafting of SiO_(2)-PS as a control sample.SiO_(2)@JNP was demonstrated to be an efficient compatibilizer for a PS/poly(methyl methacrylate)(PMMA)immiscible blend,and the droplet-matrix morphology was significantly refined.The mechanical strength and toughness of the blend were synchronously enhanced at a low content SiO_(2)@JNP optimized~0.9 wt%,with the tensile strength,elongation at break and impact strength increased by 17.7%,26.6%and 19.6%,respectively.This enhancement may be attributed to the entanglements between the grafted polymer brushes and individual components that improve the particle-bulk phase affinity and enforce interfacial adhesion.
基金funding support received from China Petrochemical Corporation(Sinopec Group).
文摘The purpose of this study is to develop novel P-Mo-V heteropoly compound catalysts for the oxidation of methacrolein to methacrylic acid.The introduction of Cu,as a modifying element,was employed to enhance the catalytic performance.Experimental results show that the addition of Cu significantly improved the catalyst performance,increasing the conversion rate of methacrolein from 17.2%to 84.2%,while the yield of methacrylic acid was boosted from 5.5%to 51.7%.A series of characterization results showed that both P-Mo-V and Cu-P-Mo-V catalysts primarily exhibited the crystal phase of[PMo_(12)O_(40)]^(3−),with a small amount of[PMo_(11)VO_(40)]^(3−)phase.However,the Cu-P-Mo-V catalyst exhibited much better oxidation–reduction ability compared to the P-Mo-V catalyst.Isolated Cu atoms were found to exist in a highly decentralized tetrahedral coordination structure,bridged by oxygen atoms within the heteropoly compound framework.The addition of Cu resulted in notable alterations in the modulation of the surface electronic structure,enhancement of oxidation–reduction ability,and optimization of the reaction pathway,thereby improving the overall catalytic activity of the catalyst.This study not only provides new insights into the modification of P-Mo-V heteropoly compound catalysts but also lays a foundation for understanding their catalytic mechanisms in organic synthesis reactions,demonstrating the potential of modifying elements in improving catalyst performance.
基金supported by the National Natural Science Foundation of China Joint Fund for Enterprise Innovation and Development,Enrichment Mechanism and Stereoscopic Development of Shale Oil in Continental Rift Basins(No.U24B6002).
文摘Temporary plugging and diversion fracturing(TPDF)is widely used to promote the uniform and complex distribution of multi-clustered hydraulic fractures(HFs)in a horizontal well of the unconventional formations.However,the migration behavior of temporary plugging agent(TPA),as a function of the concentration and particle size of TPA and cluster-perforation numbers,etc.,determining the effectiveness of this technique,remains unclear.Therefore,this study conducted innovatively a series of TPDF simulation experiments on transparent polymethyl methacrylate(PMMA)specimens(cubic block of 30 cm×30 cm×30 cm)to explore visually the migration behavior of TPA in multi-clustered HFs in a horizontal well.A laboratory hydraulic sandblasting perforation completion technique was implemented to simulate the multi-cluster perforations.All the distributions of wellbore,perforations,HFs,and TPA can be seen clearly inside the PMMA specimen post the experiment.The results show that there are four characteristic plugging positions for the TPA:mouth of HF,middle of HF,tip of HF,and the intersection of HFs.Small particle size TPA tends to migrate to the fracture tip for plugging,while large particle size TPA tends to plug at the fracture mouth.The migration of the TPA is influenced obviously by the morphology of the fracture wall.A smooth fracture wall is conducive to the migration of the TPA to the far end of HFs,but not conducive to generating the plugging zone and HF diversion.In contrast,a"leaf vein"fracture of rough wall is conducive to generating the plugging layer and the diversion of HFs,but not conducive to the migration of the TPA to the far end of HFs.The migration ability of TPA in a"shell"pattern is intermediate between the two above cases.Increasing TPA concentration can encourage TPA to migrate more quickly to the characteristic plugging position,and thereby to promote the creation of effective plugging and subsequently the multi-stage diversion of the HFs.Nevertheless,excessive concentration may cause the TPA to settle prematurely,affecting the propagation of the HFs to the far end.Increasing the number of clusters to a certain extent can encourage TPA to migrate into the HFs and form plugging,and promote the diversion.An evaluation system for the migration ability of granular TPA has been established,and it was calculated that when there is no plugging expectation target,the comprehensive migration ability of small particle size TPA is stronger than that of large particle size TPA.This research provides theoretical foundation for the optimization of temporary plugging parameters.
基金supported by the research projects AP14869428 from the Ministry of Science and Higher Education of the Republic of Kazakhstan20122022FD4135 from Nazarbayev University.
文摘The rapid development of nanotechnology has significantly revolutionized wearable electronics and expanded their functionality.Through introducing innovative solutions for energy harvesting and autonomous sensing,this research presents a cost-effective strategy to enhance the performance of triboelectric nanogenerators(TENGs).The TENG was fabricated from polyvinylidene fluoride(PVDF)and N,N'-poly(methyl methacrylate)(PMMA)blend with a porous structure via a novel optimized quenching method.The developed approach results in a highβ-phase content(85.7%)PVDF/3wt.%PMMA porous blend,known for its superior piezoelectric properties.PVDF/3wt.%PMMA modified porous TENG demonstrates remarkable electrical output,with a dielectric constant of 40 and an open-circuit voltage of approximately 600 V.The porous matrix notably increases durability,enduring over 36000 operational cycles without performance degradation.Moreover,practical applications were explored in this research,including powering LEDs and pacemakers with a maximum power output of 750mWm^(-2).Also,TENG served as a self-powered tactile sensor for robotic applications in various temperature conditions.The work highlights the potential of the PVDF/PMMA porous blend to utilize the next-generation self-powered sensors and power small electronic devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.52404155 and 52304111)State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining&Technology,Beijing(Grant No.XD2024006).
文摘Drilling and blasting,characterized by their efficiency,ubiquity,and cost-effectiveness,have emerged as predominant techniques in rock excavation;however,they are accompanied by enormous destructive power.Accurately controlling the blasting energy and achieving the directional fracture of a rock mass have become common problems in the field.A two-dimensional blasting(2D blasting)technique was proposed that utilizes the characteristic that the tensile strength of a rock mass is significantly lower than its compressive strength.After blasting,only a 2D crack surface is generated along the predetermined direction,eliminating the damage to the reserved rock mass caused by conventional blasting.However,the interior of a natural rock mass is a"black box",and the process of crack propagation is difficult to capture,resulting in an unclear 2D blasting mechanism.To this end,a single-hole polymethyl methacrylate(PMMA)test piece was used to conduct a 2D blasting experiment with the help of a high-speed camera to capture the dynamic crack propagation process and the digital image correlation(DIC)method to analyze the evolution law of surface strain on the test piece.On this basis,a three-dimensional(3D)finite element model was established based on the progressive failure theory to simulate the stress,strain,damage,and displacement evolution process of the model under 2D blasting.The simulation results were consistent with the experimental results.The research results reveal the 2D blasting mechanism and provide theoretical support for the application of 2D blasting technology in the field of rock excavation.
文摘Poly(methacrylic acid co-poloxamer) hydrogel networks were synthesized by free radical solution polymerization and their equilibrium swelling and solute permeation properties were characterized. These gels exhibited pH dependant swelling and solute diffusivity due to the formation or disruption of hydrogen bonded complexation between methacrylic acid (MAA) and etheric (EO). In neutral and basic conditions (above the swelling transition pH), the copolymer swelling was greatly higher than acid condition. In complexed hydrogels, the diffusion coefficients of vitamin B12 (VB12) were in the range of 10-10 to 10-7 cm2s-1; While in uncomplexed hydrogels, the values were about 210-6 cm2s-1. The comonomer composition and synthesis conditions have great effect on the structure, and thereby, swelling and solute diffusion characteristics of the resultant hydrogels. For the copolymers with composition of less than or more than 1:1 MAA/EO molar ratio, the plot of lnD vs 1/H-1 followed two different linear equations of 慺ree volume theory? respectively.
