In vitro corrosion resistance,antibacterial activity and cytocompatibility of a layer-by-layer assembled DNA coating on magnesium alloy

A chitosan/deoxyribonucleic acid(CHI/DNA)_(5)coating was constructed by layer-by-layer(LbL)assembly dip coating method with Mg(OH)_(2)coating as an inner protective layer on AZ31 alloy.X-ray diffractometry,X-ray photoelectron spectrometry,Fourier transform infrared spectroscopy and field-emission scanning electron microscopy were utilized to represent the chemical compositions and surface morphologies of the coatings.Electrochemical tests and hydrogen evolution measurements were implemented to confirm the good corrosion resistance of the composite coating in artificial body fluid.Antimicrobial activity of the composite coatings was tested via the plate-counting method,and the cytotoxicity of the samples was appraised by MTT assay and Live/dead staining.A double action was put into effect for the composite coating,which the inner Mg(OH)2 coating plays the part of physical barrier,and the outer(CHI/DNA)5 coating is employed as an inducer to fabricate a biocompatible Ca-P corrosion product coating during immersion,making up for its thin thickness.Otherwise,the composite coating is also beneficial for the growth of bone,resulting from the biomineralization effect of the outer polyelectrolyte multilayer.The good antibacterial property of the(CHI/DNA)5/Mg(OH)2 coating is ascribed to the contact-killing strength of CHI.Thus,the obtained(CHI/DNA)5/Mg(OH)2 coating has a wide application prospect in the field of Mg-based bone implantation.

Corrosion resistance and superhydrophobicity of one-step polypropylene coating on anodized AZ31 Mg alloy

Superhydrophobic coatings have been considerably used in corrosion and its protection of metallic Mg.And the comprehensive performance(hydrophobicity,bonding strength,and corrosion resistance,etc.)of the top coating may be highly dependent on the physical and chemical properties of the primer or under coat.Herein,an integrated superhydrophobic polypropylene(PP)coating was fabricated on the micro-arc oxidized Mg substrate via one-step dipping.Surface morphologies and chemical compositions of the composite coating were examined through Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),and field-emission scanning electron microscopy(FESEM)together with X-ray photoelectron spectroscopy(XPS).The surface wettability of the coating was determined by contact angle and sliding angle.The corrosion-resistant performance was evaluated via electrochemical and immersion measurements.The results showed that the hybrid coating possessed micron-scaled granular structure on the surface with a high water contact angle of 167.2±0.8°and a low water sliding angle of 2.7±0.5°.The corrosion resistance of superhydrophobic coating was obviously enhanced with a low corrosion current density of 8.76×10^(−9)A/cm^(2),and the coating still maintained integrity after 248 h of immersion in 3.5wt%NaCl aqueous solution.The MAO coating provides better adhesion of PP to the surface.Hence,the superhydrophobic coating exhibited superior bonding strength,corrosion resistance and durability.

Rambutan-like hollow carbon spheres decorated with vacancy-rich nickel oxide for energy conversion and storage

Transition metal oxides hold great promise for lithium-ion batteries(LIBs)and electrocatalytic water splitting because of their high abundance and high energy density.However,designing and fabrication of efficient,stable,high power density electrode materials are challenging.Herein,we report rambutan-like hollow carbon spheres formed by carbon nanosheet decorated with nickel oxide(NiO)rich inmetal vacancies(denoted as h-NiO/C)as a bifunctional electrode material for LIBs and electrocatalytic oxygen evolution reaction(OER).When being used as the anode of LIBs,the h-NiO/C electrode shows a large initial capacity of 885mAh g−1,a robust stability with a high capacity of 817mAh g−1 after 400 cycles,and great rate capability with a high reversible capacity of 523mAh g−1 at 10Ag−1 after 600 cycles.Moreover,working as an OER electrocatalyst,the h-NiO/C electrode shows a small overpotential of 260mV at 10mAcm−2,a Tafel slope of 37.6mVdec−1 along with good stability.Our work offers a cost-effective method for the fabrication of efficient electrode for LIBs and OER.

Vacancies and interfaces engineering of core-shell heterostuctured NiCoP/NiO as trifunctional electrocatalysts for overall water splitting and zinc-air batteries

The electronic structures and properties of electrocatalysts,which depend on the physicochemical structure and metallic element components,could significantly affect their electrocatalytic performance and their future applications in Zn-air battery(ZAB)and overall water splitting(OWS).Here,by combining vacancies and heterogeneous interfacial engineering,three-dimensional(3D)core-shell NiCoP/NiO heterostructures with dominated oxygen vacancies have been controllably in-situ grown on carbon cloth for using as highly efficient electrocatalysts toward hydrogen and oxygen electrochemical reactions.Theoretical calculation and electrochemical results manifest that the hybridization of NiCoP core with NiO shell produces a strong synergistic electronic coupling effect.The oxygen vacancy can enable the emergence of new electronic states within the band gap,crossing the Fermi levels of the two spin components and optimizing the local electronic structure.Besides,the hierarchical core-shell NiCoP/NiO nanoarrays also endow the catalysts with multiple exposed active sites,faster mass transfer behavior,optimized electronic strutures and improved electrochemical performance during ZAB and OWS applications.

Microbiologically influenced corrosion resistance enhancement of coppercontaining high entropy alloy Fe_(x)Cu_(1−x)CoNiCrMn against Pseudomonas aeruginosa

To enhance the microbiologically influenced corrosion(MIC)resistance of FeCoNiCrMn high entropy alloy(HEAs),a series of Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs were prepared.Microstructural characteristics,corrosion behavior(morphology observation and electrochemical properties),and antimicrobial performance of Fe_(x)Cu_((1−x))CoNiCrMn HEAs were evaluated in a medium inoculated with typical corrosive microorganism Pseudomonas aeruginosa.The aim was to identify copper-containing FeCoNiCrMn HEAs that balance corrosion resistance and antimicrobial properties.Results revealed that all Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs exhibited an FCC(face centered cubic)phase,with significant grain refinement observed in Fe_(0.75)Cu_(0.25)CoNiCrMn HEA.Electrochemical tests indicated that Fe_(0.75)Cu_(0.25)CoNiCrMn HEA demonstrated lower corrosion current density(i_(corr))and pitting potential(E_(pit))compared to other Fe_(x)Cu_((1−x))CoNiCrMn HEAs in P.aeruginosa-inoculated medium,exhibiting superior resistance to MIC.Anti-microbial tests showed that after 14 d of immersion,Fe_(0.75)Cu_(0.25)CoNiCrMn achieved an antibacterial rate of 89.5%,effectively inhibiting the adhesion and biofilm formation of P.aeruginosa,thereby achieving resistance to MIC.

Corrosion resistance of bioinspired DNA-induced Ca-P coating on biodegradable magnesium alloy

Bioinspired coatings with decreased corrosion rate and enhanced bond strength are at the core of future clinic applications on degradable magnesium(Mg)-based implants.The hybrid of organic and inorganic compounds offers a strategy to fabricate biodegradable,biocompatible and compact coatings on biomedical Mg alloys.Hereby,a comparison with and without DNA addition was made on the corrosion resistance and adhesion strength of Ca-P coatings fabricated on AZ31 alloy via hydrothermal deposition.The morphology,chemical composition,and crystallographic structure of the coatings were investigated by means of SEM,EDS and FTIR as well as XRD before and after corrosion tests.Corrosion resistance was evaluated via potentiodynamic polarization curves,electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests in Hank’s solution.Results show that the coatings are mainly characterized by tricalcium phosphate(TCP),dicalcium phosphate anhydrous(DCPA)and calcium-deficient hydroxyapatite(CDHA).The presence of DNA leads to the formation of Ca-P coating with improved corrosion resistance and adhesion strength.Additionally,the formation mechanism for DNA-induced Ca-P coating is proposed.The DNA-induced Ca-P coating exhibits a promising future for controlling the corrosion rate of biodegradable Mg alloys.©2019 Published by Elsevier B.V.on behalf of Chongqing University.

Advances in bioorganic molecules inspired degradation and surface modifications on Mg and its alloys

Mg alloys possess biodegradability,suitable mechanical properties,and biocompatibility,which make them possible to be used as biodegradable implants.However,the uncontrollable degradation of Mg alloys limits their general applications.In addition to the factors from the metallic materials themselves,like alloy compositions,heat treatment process and microstructure,some external factors,relating to the test/service environment,also affect the degradation rate of Mg alloys,such as inorganic salts,bioorganic small molecules,bioorganic macromolecules.The influence of bioorganic molecules on Mg corrosion and its protection has attracted more and more attentions.In this work,the cutting-edge advances in the influence of bioorganic molecules(i.e.,protein,glucose,amino acids,vitamins and polypeptide)and their coupling effect on Mg degradation and the formation of protection coatings were reviewed.The research orientations of biomedical Mg alloys in exploring degradation mechanisms in vitro were proposed,and the impact of bioorganic molecules on the protective approaches were also explored.

Moisture-sensitive torsional cotton artificial muscle and textile

Developing moisture-sensitive artificial muscles from industrialized natural fibers with large abundance is highly desired for smart textiles that can respond to humidity or temperature change.However,currently most of fiber artificial muscles are based on non-common industrial textile materials or of a small portion of global textile fiber market.In this paper,we developed moisture-sensitive torsional artificial muscles and textiles based on cotton yarns.It was prepared by twisting the cotton yarn followed by folding in the middle point to form a self-balanced structure.The cotton yarn muscle showed a torsional stroke of 42.55°/mm and a rotational speed of 720 rpm upon exposure to water moisture.Good reversibility and retention of stroke during cyclic exposure and removal of water moisture were obtained.A moisturesensitive smart window that can close when it rains was demonstrated based on the torsional cotton yarn muscles.This twist-based technique combining natural textile fibers provides a new insight for construction of smart textile materials.

Correlating the crystal structure and facet of indium oxides with their activities for CO_(2)electroreduction

Constructing structure-function relationships is critical for the rational design and development of efficient catalysts for CO_(2) electroreduction reaction(CO_(2)RR).In_(2)O_(3) is well-known for its specific ability to produce formic acid.However,how the crystal phase and surface affect the CO_(2)RR activity is still unclear,making it difficult to further improve the intrinsic activity and screen for the most active structure.In this work,cubic and hexagonal In_(2)O_(3) with different stable surfaces((111)and(110)for cubic,(120)and(104)for hexagonal)are investigated for CO_(2)RR.Theoretical results demonstrate that the adsorption of reactants on cubic In_(2)O_(3) is stronger than that on hexagonal In_(2)O_(3),with the cubic(111)surface being the most active for CO_(2)RR.In experiments,synthesized cubic In_(2)O_(3) nanosheets with predominantly exposed(111)surfaces exhibited a high HCOO^(-)Faradaic efficiency(87.5%)and HCOO^(–)current density(–16.7 mA cm^(-2))at–0.9 V vs RHE.In addition,an aqueous Zn-CO_(2) battery based on a cubic In2O3 cathode was assembled.Our work correlates the phases and surfaces with the CO_(2)RR activity,and provides a fundamental understanding of the structure-function relationship of In_(2)O_(3),thereby contributing to further improvements in its CO_(2)RR activity.Moreover,the results provide a principle for the directional preparation of materials with optimal phases and surfaces for efficient electrocatalysis.

Revealing of the ultrafast third-order nonlinear optical response and enabled photonic application in two-dimensional tin sulfide

Black phosphorus(BP), a typical mono-elemental and two-dimensional(2D) material, has gathered significant attention owing to its distinct optoelectronic properties and promising applications, despite its main obstacle of long-term stability. Consequently, BP-analog materials with long-term chemical stability show additional potential. In this contribution, tin sulfide(SnS), a novel two-elemental and 2D structural BP-analog monochalcogenide, has been demonstrated to show enhanced stability under ambient conditions. The broadband nonlinear optical properties and carrier dynamics have been systematically investigated via Z-scan and transient absorption approaches. The excellent nonlinear absorption coefficient of 50.5 × 10^-3 cm∕GW, 1 order of magnitude larger than that of BP, endows the promising application of SnS in ultrafast laser generation. Two different decay times of τ1~873 fs and τ2~96.9 ps allow the alteration between pure Q switching and continuous-wave(CW) mode locking in an identical laser resonator. Both mode-locked and Q-switched operations have been experimentally demonstrated using an SnS saturable absorber at the telecommunication window. Femtosecond laser pulses with tunable wavelength and high stability are easily obtained, suggesting the promising potential of SnS as an efficient optical modulator for ultrafast photonics. This primary investigation may be considered an important step towards stable and high-performance BP-analog material-based photonic devices.

In vitro degradation and cytocompatibility of a low temperature in-situ grown self-healing Mg-Al LDH coating on MAO-coated magnesium alloy AZ31

Basically,Mg–Al layered double hydroxide(LDH)coatings are prepared on the surface of micro-arc oxidation(MAO)coated magnesium(Mg)alloys at a high temperature or a low pH value.This scenario leads to the growth rate of LDH coating inferior to the dissolution rate of the MAO coating.This in turn results in limited corrosion resistance of the composite coating.In this study,a Mg–Al LDH coating on MAO-coated Mg alloy AZ31 is prepared through a water bath with a higher pH(13.76)at a lower temperature(60℃).FE-SEM,EDS,XRD,XPS,and FT-IR are applied to analyze the surface morphology,chemical compositions,and growth process.Electrochemical polarization,electrochemical impedance spectroscopy(EIS)and hydrogen evolution tests are employed to evaluate the corrosion resistance of the samples.The results disclose that the MAO coating is completely covered by the nanosheet-structured LDH coating with a thickness of approximately 3.8μm.The corrosion current density of the MAO-LDH composite coating is decreased four orders of magnitude in comparison to its substrate;the presence of a wide passivation region in anodic polarization branch demonstrates its strong self-healing ability,indicating the hybrid coating possesses excellent corrosion resistance.The formation mechanism of the LDH coating on the MAO-coated Mg alloy is proposed.Furthermore,the cytocompatibility is assessed via an indirect extraction test for MC3T3-E1 pre-osteoblasts,which indicates an acceptable cytocompatibility of osteoblasts for the composite coating.

Selective laser melting of bulk immiscible alloy with enhanced strength:Heterogeneous microstructure and deformation mechanisms

To overcome the dimension limits of immiscible alloys produced by traditional techniques and enhance their mechanical properties,bulk Cu-Fe-based immiscible alloy with abundant nanotwins and stacking faults was successfully produced by selective laser melting(SLM).The SLM-produced bulk immiscible alloy displays a heterogeneous microstructure characterized by micro-scaledγ-Fe particles dispersed in fineε-Cu matrix with a high fraction(~92%)of high-angle grain boundaries.Interestingly,abundant nanotwins and stacking faults are generated in the interior of nano-scaledγ-Fe particles embedded withinε-Cu matrix.The heterogeneous interface of soft domains(ε-Cu)and hard domains(γ-Fe)not only induces the geometrically necessary dislocations(GNDs)but also affects the dislocation propagation during plastic deformation.Therefore,the bimodal heterogeneous interface,and the resistance of nanotwins and stacking faults to the propagation of partial dislocation make the bulk immiscible alloy exhibit an enhanced strength of~590 MPa and a good ductility of~8.9%.

Effects of surface modifications on the physicochemical properties of iron oxide nanoparticles and their performance as anticancer drug carriers

The feature of the surface coating can affect important properties of iron oxide nanoparticles(IONPs), it is therefore critical for further understanding how these materials react to physiological conditions, which is still needed to fully exploit the potential of IONPs for their theranostic applications. In this work, we prepared IONPs which surface were modified with citric acid(CA), chitosan(CS) and folic acid conjugated chitosan(FA-g-CS). respectively. Their physicochemical properties were investigated using FT-IR, TEM,powder XRD, VSM, TGA, DLS and zeta potential. We found that CA-IONP dispersion was composed of monocrystalline particles while CS-IONP and FA-g-CS-IONP were composed of polycrystalline aggregates. All IONPs retained the crystalline structure of magnetite and exhibited the superparamagnetic behavior. Their saturation magnetization decreased with the increase in the amount of their organic coatings. Their drug loading capacities, drug release patterns and in vitro anticancer efficiencies were studied by using doxorubicin(DOX) as a model drug. DOX@CS-IONP and DOX@FA-g-CSIONP exhibited lower drug loading while showing higher water dispersity when compared with DOX@CA-IONP. All IONPs were surface charged and they tended to agglomerate in medium with high pH value and ionic strength. In the presence of chitosan or FA-g-CS coatings, their DOX release rate was slowed down compared with that of DOX@CA-IONP. Unloaded IONPs exhibited nearly no cytotoxicity on both cancer cells and normal cells in the presence of chitosan and FA-g-CS when compared with CA-IONP which presented high cytotoxicity. However, DOX@FA-g-CS-IONP showed significantly cytotoxicity on folate receptors(FRs) positive breast cancer cells while exhibiting nearly no cytotoxicity on FRs negative normal cells. Results presented in this study were valuable to the design and fabrication of IONPs-based system for better theranostic applications.

Hierarchical TiO2 nanorods with a highly active surface for photocatalytic CO_(2) reduction

Photocatalytic carbon dioxide reduction reaction(CO_(2)RR)has been considered as one of most effective ways to solve the current energy crisis and environmental problems.However,the practical application of photocatalytic CO_(2)RR is largely hindered by lock of efficient catalyst.Here,hierarchical titanium dioxide(TiO_(2))nanostructures with a highly active{001}surface were successfully synthesized by a facile approach from metal Ti powders.The obtained hierarchical TiO_(2)nanostructures were composed of TiO_(2)nanorods,which have a diameter about 5–10 nm and a length of several micrometers.It is found that these nanorods have exposed{001}facets.On the other hand,these hierarchical TiO_(2)nanostructures have a good light-harvesting efficiency with the help of TiO_(2)nanorods component and large specific surface area.Therefore,these hierarchical TiO_(2)nanostructures exhibit a much better activity for photocatalytic CO_(2)reduction than that of commercial TiO_(2)(P25).This high activity can be attributed to the synergistic effects of active surface,efficient charge transfer along nanorods and good light harvesting in the nanorod-hierarchical nanostructures.

Membraneless reproducible MoS2 field-effect transistor biosensor for high sensitive and selective detection of FGF21

Fibroblast growth factor 21(FGF21)serves as an essential biomarker for early detection and diagnosis of nonalcoholic fatty liver disease(NAFLD).It has received a great deal of attention recently in efforts to develop an accurate and effective method for detecting low levels of FGF21 in complex biological settings.Herein,we demonstrate a label-free,simple and high-sensitive field-effect transistor(FET)biosensor for FGF21 detection in a nonaqueous environment,directly utilizing two-dimensional molybdenum disulfide(MoS2)without additional absorption layers.By immobilizing anti-FGF21 on MoS2 surface,this biosensor can achieve the detection of trace FGF21 at less than 10 fg mL-1.High consistency and satisfactory reproducibility were demonstrated through multiple sets of parallel experiments for the MoS2 FETs.Furthermore,the biosensor has great sensitivity to detect the target FGF21 in complex serum samples,which demonstrates its great potential application in disease diagnosis of NAFLD.Overall,this study shows that thin-layered transition-metal dichalcogenides(TMDs)can be used as a potential alternative platform for developing novel electrical biosensors with high sensitivity and selectivity.

Phase Selection and Microhardness of Directionally Solidified AlCoCrFeNi_(2.1) Eutectic High-Entropy Alloy

In the present work,the solidification behaviors and microhardness of directionally solidified AlCoCrFeNi_(2.1) eutectic highentropy alloy(EHEA)obtained at different growth velocities are investigated.The microstructure of the as-cast AlCoCrFeNi_(2.1) EHEA is composed of bulky dendrites(NiAl phase)and lamellar eutectic structures,indicating that the actual composition of the alloy slightly deviates from the eutectic point.However,it is interesting to observe that the full lamellar structure of this alloy is obtained through directional solidification.In order to explain this phenomenon,the maximum interface temperature criterion and the interface response function(IRF)theory are applied to calculate the velocity range of the transition from the primary phase to the eutectic,which is 1.2–2×10^(4)μm/s.Furthermore,microhardness is one of the important parameters to measure the mechanical properties of materials.Therefore,the microhardness test is performed,and the test result indicates that the microhardness(HV)increased with increasing growth velocity(V)or decreased with increasing lamellar spacing(λ).The dependences ofλand HV on V are determined by using a linear regression analysis.The relationships between theλ,V and HV are given as:λ=11.62V^(-0.48),HV=305.5V 0.02 and HV=328.1λ^(0.04),respectively.The microhardness of the AlCoCrFeNi_(2.1) EHEA increases from 312.38 HV to 329.54 HV with the increase in growth velocity(5–200μm/s).Thus,directional solidification is an effective method to improve the mechanical properties of alloys.

In vitro degradation and multi-antibacterial mechanisms ofβ-cyclodextrin@curcumin embodied Mg(OH)_(2)/MAO coating on AZ31 magnesium alloy

It is a challenging task to prepare a coating on Mg alloys for desirable corrosion resistance,good antibac-terial ability and biocompatibility.In this research work,an in-situ Mg(OH)_(2)coating incorporated with sodium alginate(SA)andβ-cyclodextrin(β-CD)@curcumin(Cur)was formed on the surface of micro arc oxidation(MAO)coated AZ31 alloy via a low temperature hydrothermal method.Characterization tech-niques such as X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectrometer(FT-IR)and scanning electron microscope(SEM)were employed to characterize the chemi-cal composition and surface morphology of the coatings.The corrosion protection ability of the coatings was monitored via electrochemical polarization,hydrogen evolution and immersion tests.Photothermal antibacterial ability and cytocompatibility of the coatings were evaluated by plate counting method under the irradiation of 808 nm-near infrared light,in vitro cytotoxicity tests(MTT)and live/dead cell staining.The results indicate that a chelation of the organic molecules led to the formation of a MAO/(β-CD@Cur)-SA-Mg(OH)_(2)coating with excellent corrosion protection,multi-antibacterial ability and almost no toxic-ity to the cells.Especially,the coating provided photothermal performance through the light absorption of Cur,which was encapsulated byβ-CD to improve its bioavailability.SA enhanced the binding force between the drug and the substrate.This novel coating designated the potential application on bioab-sorbable magnesium alloys.

Reduction behavior of tungsten oxide with and without scandia doping

As an important powder material for scandate cathode,Sc_(2) O_(3)-doped WO_(3) powder together with hollow spherical WO_(3) for comparison was prepared by spraydrying method.The reduction behavior and kinetics of pure WO_(3) and Sc_(2) O_(3)-doped WO_(3) were studied by temperatureprogrammed reduction(TPR) method.It is found that scandia doping can decrease the reduction activation energy of WO_(3) and thus lower the reduction temperature and increase the reduction rate.Based on the kinetics results,the reduction techniques are presented.The obtained powder has a narrow size distribution in the range of 0.6-0.8 μm.

Amphiphilic block copolymers directed synthesis of mesoporous nickel-based oxides with bimodal mesopores and nanocrystal-assembled walls

Mesoporous late-transition metal oxides have great potential in applications of energy,catalysis and chemical sensing due to their unique physical and chemical properties.However,their synthesis via the flexible and scalable soft-template method remain a great challenge,due to the weak organic-inorganic interaction between the frequently used surfactants(e.g.,Pluronic-type block copolymers) and metal oxide precursors,and the low crystallization temperature of metal oxides.In this study,ordered mesoporous NiO with dual mesopores,high surface area and well-interconnected crystalline porous frameworks have been successfully synthesized via the facile solvent evaporation-induced co-assembly(EICA) method,by using lab-made amphiphilic diblock copolymer polystyrene-b-poly(4-vinylpyridine)(PS-b-P4 VP) as both the structure-directing agent(the soft template) and macromolecular chelating agents for nickel species,THF as the solvent,and nickel acetylacetonate(Ni(acac)2) as inorganic precursor.Similarly,by using Ni(acac)2 and Fe(acac)3 as the binary precursors,ordered mesoporous Fedoped NiO materials can be obtained,which have bimodal mesopores of large mesopores(32.5 nm) and secondary mesopores(4.0-11.5 nm) in the nanocrystal-assembled walls,high specific surface areas(~74.8 m^2/g) and large pore value(~0.167 cm^3/g).The obtained mesoporous Fe-doped NiO based gas sensor showed superior ethanol sensing performances with good sensitivity,high selectivity and fast response-recovery dynamics.

Corrosion resistance of self-cleaning silane/polypropylene composite coatings on magnesium alloy AZ31

Magnesium(Mg)and its alloys have been widely used in a variety of industrial fields,however,the high corrosion rate and surface contamination restrict their applications.In this study,a corrosion-resistant polymer coating with self-cleaning properties on Mg alloy AZ31 was successfully fabricated via a pretreatment of amino-silane(poly(3-aminopropyl)trimethoxysilane,PAPTMS)and subsequently covered with a polypropylene(PP)film.Surface morphology and chemical compositions were examined using field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),and Fourier transform infrared spectrophotometry(FT-IR)and X-ray photoelectron spectroscopy(XPS)as well.Contact angle was measured to determine hydrophobicity of the composite coatings.Water permeability of the coatings was evaluated through electrochemical impedance spectroscopy(EIS).Corrosion resistance of the coating was investigated using electrochemical and hydrogen evolution tests.Results indicated that PAPTMS/PP coatings possessed a micrometer-scaled porous spherical microstructure,and super-hydrophobicity with high water contact angle(162±3.4°)and low sliding angle(5±0.6°)due to the low surface energy(10.38 mJ/m2).Moreover,the coating exhibited a smaller water diffusion coefficient(8.12×10-10 cm2/s)and water uptake volume fraction(24.5%),demonstrating low water permeability and good physical barrier performance.As a result,the corrosion current density of PAPTMS/PP coating exhibited approximately three orders of magnitude lower than that of the AZ31 substrate,suggesting excellent corrosion resistance.Finally,corrosion-resistant mechanism of the hybrid coating was proposed.