Atomic Force Microscopy Measurements Research Articles

One Step Closer to Coatings Applications Utilizing Self-Stratification: Effect of Rheology Modifiers.

Self-stratification of model blends of colloidal spheres has recently been demonstrated as a method to form multifunctional coatings in a single pass. However, practical coating formulations are complex fluids with upward of 15 components. Here, we investigate the influence of three different rheology modifiers (RMs) on the stratification of a 10 wt % 7:3 w:w blend of 270 and 96 nm anionic latex particles that do not stratify without RM. However, addition of a high molar mass polysaccharide thickener, xanthan gum, raises the viscosity and corresponding Péclet number enough to achieve small-on-top stratification as demonstrated by atomic force microscopy (AFM) measurements. Importantly, this was possible due to minimal particle-rheology modifier interactions, as demonstrated by the bulk rheology. In contrast, Carbopol 940, a microgel-based RM, was unable to achieve small-on-top stratification despite a comparable increase in viscosity. Instead, pH-dependent interactions with latex particles lead to either laterally segregated structures at pH 3 or a surface enrichment of large particles at pH 8. Strong RM-particle interactions are also observed when the triblock associative RM HEUR10kC12 is used. Here, small-on-top, large-enhanced, and randomly mixed structures were observed at respectively 0.01, 0.1, and 1 wt % HEUR10kC12. Combining rheology, dynamic light scattering, and AFM results allows the mechanisms behind the nonmonotonic stratification in the presence of associative RMs to be elucidated. Our results highlight that stratification can be predicted and controlled for RMs with weak particle interactions, while a strong RM-particle interaction may afford a wider range of stratified structures. This takes a step toward successfully harnessing stratification in coatings formulations.

Spin selection in atomic-level chiral metal oxide for photocatalysis

The spin degree of freedom is an important and intrinsic parameter in boosting carrier dynamics and surface reaction kinetics of photocatalysis. Here we show that chiral structure in ZnO can induce spin selectivity effect to promote photocatalytic performance. The ZnO crystals synthesized using chiral methionine molecules as symmetry-breaking agents show hierarchical chirality. Magnetic circular dichroism spectroscopic and magnetic conductive-probe atomic force microscopic measurements demonstrate that chiral structure acts as spin filters and induces spin polarization in photoinduced carriers. The polarized carriers not only possess the prolonged carrier lifetime, but also increase the triplet species instead of singlet byproducts during reaction. Accordingly, the left- and right-hand chiral ZnO exhibit 2.0- and 1.9-times higher activity in photocatalytic O2 production and 2.5- and 2.0-times higher activities in contaminant photodegradation, respectively, compared with achiral ZnO. This work provides a feasible strategy to manipulate the spin properties in metal oxides for electron spin-related redox catalysis.

Biomass‐functionalized graphene oxide toward waterborne polyurethane composite with enhanced flame retardancy and hydrophobicity

AbstractIn this study, phytic acid‐polydopamine functionalized GO (GO@PA@PDA) was first synthesized. The DOPO derivatives, hydroxyl‐terminated polydimethylsiloxane (PDMS) and GO@PA@PDA were incorporated into waterborne polyurethane (WPU) by in situ polymerization. The chemical structure of GO@PA@PDA was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X‐ray diffraction, ultraviolet–visible (UV–vis) spectroscopy and scanning electron microscopy. A cone calorimeter test and a universal testing machine investigated the flame retardancy and mechanical properties of GO@PA@PDA modified waterborne polyurethane (GPD‐WPU). The results showed that the incorporation of GO@PA@PDA into WPU significantly enhanced the flame retardancy by reducing the heat release rate, total heat release, smoke production rate, and total smoke production. Furthermore, the mechanical properties of the GPD‐WPU composite films increased with the dosage of GO@PA@PDA from 0 to 2.0 wt%, and decreased slightly afterward. The contact angle and atomic force microscope measurements showed that the addition of GO@PA@PDA increased the surface roughness of GPD‐WPU composite film, thereby improving the hydrophobicity of GPD‐WPU composite films. Afterward, GPD‐WPU as a finishing agent was coated on polyester fabric. The experimental results of limiting oxygen index (LOI) and the vertical burning test indicated that when the dosage of GO@PA@PDA was 2.5 wt% in GPD‐WPU, after‐flame time, after‐glow time, damage length and LOI value of the coated polyester fabric were 2.9 s, 0 s, 6.8 cm, and 28.6%, respectively.

A Comparative Analysis on the Crystalline Behavior, Topographical, Photoluminescence, and Leakage Current Characteristics of BiFeO3 Nanopowders and Thin Films

AbstractThin films and nanocrystalline powders of BiFeO3 (BFO) are prepared from pulsed laser deposition (PLD) and sol–gel process, respectively. Their grain sizes, microstrain, morphological features, leakage current characteristics, and photoluminescence (PL) emission behavior are investigated and compared with each other. X‐ray diffraction (XRD) technique has been utilized to compute the grain sizes and crystalline strain values for the thin films and nanopowders of BFO through Williamson–Hall (W–H) plots. XRD and Raman peaks of the deposited thin film and synthesized nanopowders of BFO confirm the formation of rhombohedral unit cell character and its vibrational structure. Topographical analysis of nanopowders and thin films of BFO from scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements reveals the spherical morphology of grown particles. Suppression of emission peaks, as noticed from PL spectra for BFO nanopowders and thin film, indicates the possible electron defect level transitions due to oxygen vacancies. Leakage current density studies suggest the detectable flow of current in both study of specimen.

Optical properties of polyaniline/modified graphene oxide nanocomposites

In this research, the complex refractive index of polyaniline (PANI)/hexamethylene diisocyanate-modified graphene oxide (HDI-GO) nanocomposites has been obtained. The PANI/HDI-GO nanocomposites were prepared via in situ polymerization of aniline monomer in the presence of HDI-GO nanofillers, and their crystalline structure and surface morphology were investigated via X-ray diffraction (XRD) and atomic force microscopy (AFM) measurements. Then, the experimental reflectance and transmittance for pure PANI and PANI/HDI-GO nanocomposite films with HDI-GO contents of 0.5, 1 and 2 wt% deposited on glass substrates were measured using UV-Vis spectrophotometry within the spectral region 300–900 nm. Then, the refractive index and extinction coefficient have been obtained using a novel method developed by the authors. The model is based on the generalized Scattering Matrix Method, which is used to obtain the theoretical values for the thin film/substrate reflectance and transmittance. Root mean square errors obtained are systematically lower than 0.21%, which corroborates the excellent accuracy of the model. The proposed method does not require sophisticated equipment, just a spectrophotometer, to obtain the complex refractive index of a thin film from transmittance and reflectance measurements.

Studies of temperature-dependent Raman spectra of thin PtSe2 layers on Al2O3 substrate

The results of temperature-dependent Raman spectroscopy studies of thin layers of PtSe2 (1–10 monolayers) deposited on an Al2O3 substrate are disscused in this paper. A redshift of the vibrational Raman modes (Eg and A1g) is observed when the thickness of PtSe2 and temperature increase. The results allow for determining the thickness of the PtSe2 layer deposited on the Al2O3 substrate by analysing the Raman shift of the PtSe2 modes (Eg and A1g) and the screening effects on the surface vibration mode (A1g). The other original result is the determination of the stresses and doping effects in PtSe2 for the considered range of layer thicknesses by analyses of the correlative plot. Finally, the thermal dependences of the Raman spectra are discussed regarding Raman shifts and intensity. The atomic force microscopy measurements show the presence of residual contamination with surface densities varying between samples.

The performance and mechanism for photocatalytic degradation of methylene blue catalyzed by ultrathin NiAl-layered double hydroxides

Ultrathin materials are widely used in various photocatalytic reactions due to their large specific surface area, multi-surface active sites, easy carrier separation and transport. In this work, ultrathin NiAl-layered double hydroxides (U-LDHs) nanosheets were prepared by a urea-assisted strategy for photocatalytic degradation of methylene blue. Atomic force microscopy (AFM) measurements show that the thickness of U-LDHs nanosheet is generally between 3 and 8 nm, with a wide pore size distribution and a high specific surface area (109 m2/g). U-LDHs nanosheets can remove 92.42% of methylene blue after 90 min light irradiation, which is nearly 40% higher than that of bulk NiAl-LDHs (B-LDHs). In addition, combined with photoelectric performance characterization and density functional theory calculation, it is confirmed that the U-LDHs nanosheets are much better to the separation and transfer of photogenerated carriers compared with the bulk LDHs. Besides, U-LDHs is conducive to adsorb oxygen to generate superoxide radicals, promoting the progress of photocatalytic reactions and significantly improving photodegradation performance.

Low-temperature, single-source, chemical vapor deposition of molybdenum nitride thin films

The 1,4-di-tert-butyl-1,3-diazabutadiene adduct of bis(tert-butylimido)dichloro-molybdenum(VI), (tBuN)2MoCl2⋅dad, was used as a single-source precursor for the chemical vapor deposition of molybdenum nitride from 350–600 °C. Deposition at 400 °C had a growth rate of 55 nm h−1 and was comprised of a mixture of Mo2N and MoN, based on x-ray photoelectron spectroscopy and grazing-incidence x-ray diffraction results. The films are essentially featureless and are as smooth as the underlying substrate, based on atomic force microscopy measurements. Because the depositions could be carried out at a low temperature, there was minimal carbon (1.4%) inclusion in the film as shown by XPS.

Anisotropy of the Tribological Performance of Periodically Oxidated Laser-Induced Periodic Surface Structures

Laser-induced periodic surface structures (LIPSS) enable advanced surface functionalization with broad applications in various fields such as micro- and nanoelectronics, medicine, microbiology, tribology, anti-icing systems, and more. This study demonstrates the possibility of achieving anisotropy in the tribological behavior of C45-grade steel structured by nanosecond laser radiation using the LIPSS method. The lateral surface of the steel roller was irradiated with a pulsed Nd:YAG laser at an optimum intensity I = 870 MW/cm2 for the formation of LIPSS. Two sets of samples were formed with LIPSS that were perpendicular and parallel to the roller’s rotational motion direction. The Raman intensity maps revealed that the LIPSS structure consisted of periodically arranged oxides at the top of hills. At the same time, the valleys of the LIPSS structures were almost not oxidized. These results correlated well with scanning electron microscopy energy dispersive X-ray spectroscopy mapping and atomic force microscopy measurements. A comparison of Raman and X-ray photoelectron spectroscopy spectra revealed that both the magnetite phase and traces of the hematite phase were present on the surface of the samples. Tribological tests were performed in two cycles with periodic changes in the normal clamping force and sliding speed. It was found that the LIPSS structures which were formed perpendicularly to the sliding direction on the roller had a significantly greater impact on the friction processes. Structures oriented perpendicular to the direction of motion had a positive influence on reducing the energy consumption of a friction process as well as increasing the wear resistance compared to LIPSS formed parallel to the direction of motion or ones having a non-texturized surface. Laser texturing to produce LIPSS perpendicular to the direction of motion could be recommended for friction pairs operating under low-load conditions.

Simultaneous detection of force and tunneling current in electrolyte solution by using qPlus sensor.

We have developed a sensor for simultaneous measurement of atomic force microscopy (AFM) and scanning tunneling microscopy (STM) under liquid environments. The sensor, which is based on the qPlus sensor, is equipped with an insulated conductive tip. Owing to its electrical insulation except for the tip apex, the developed sensor enabled simultaneous detection of tip-sample interaction force and tunneling current, suppressing the Faradaic leakage current. As a fundamental demonstration, we performed simultaneous AFM/STM imaging in an electrolyte solution by using the developed sensor.

Multiscale Characterization of Rejuvenated RAP Binders

Abstract Reclaimed asphalt pavement (RAP) is increasingly being utilized in asphalt pavements because of the high cost and scarcity of virgin asphalt materials. However, because RAP is a stiff material, it requires careful engineering to prevent cracking. Recycling agents have shown the ability to partially restore the properties of RAP binders if applied in a proper type and dose. Many studies investigated the impact of recycling agents when added to blends of virgin and RAP binders, but only a few investigated their effectiveness when applied to only RAP binders. The aim of this paper is to investigate the effect of various types and doses of recycling agents on the properties of RAP binders. Rheological properties were measured using a dynamic shear rheometer (DSR). Fourier-transform infrared spectroscopy was utilized to measure the degree of oxidation of the rejuvenated RAP binders. Furthermore, atomic force microscopy (AFM) tests were conducted to measure the morphology and modulus of rejuvenated RAP binders at the nanoscale. Finally, AFM measurements were used to calculate a rejuvenation index (RI), which was developed in an earlier study by the authors to assess the effectiveness of recycling agents in resisting the adverse effects of aging. DSR results demonstrated that the inclusion of recycling agents lowered the stiffness of the RAP binders. AFM morphology images revealed the presence of a large number and varying sizes of phase associations in the RAP binders. These phase associations became more pronounced with aging. Some recycling agents partially reversed the aging effect by reducing the area occupied by these associations. Nonetheless, after long-term aging, the effect of recycling agents diminished. The results of this study revealed that characterizing rejuvenated RAP binders at both the microscale and macroscale levels can indicate the effectiveness of recycling agents and aid in the selection of type or dose of recycling agent.

Thermal atomic layer etching of CoO using acetylacetone and ozone: Evidence for changes in oxidation state and crystal structure during sequential exposures

Thermal atomic layer etching (ALE) of CoO was demonstrated using sequential exposures of acetylacetone (Hacac) and ozone (O3). During the surface reactions, Hacac can remove CoO according to: CoO + 2Hacac → Co(acac)2 + H2O. Ozone was employed to eliminate carbon residue resulting from Hacac adsorption. In situ spectroscopic ellipsometry observed a linear decrease in CoO film thickness versus Hacac and O3 exposures with an etch rate of 0.43 Å/cycle at 250 °C. The surface of the CoO film was also observed to undergo changes in oxidation state and crystal structure with each reactant exposure. Ex situ grazing incidence X-ray diffraction (GIXRD) studies revealed that the initial h-CoO thin films were oxidized to c-Co3O4 by O3. Subsequently, the GIXRD analysis showed that the c-Co3O4 thin films were reduced to c-CoO by Hacac. X-ray photoelectron spectroscopy investigations confirmed the oxidation state of the various cobalt oxides. Quadrupole mass spectrometry measurements observed Co(acac)2 etch products during Hacac exposures on Co3O4 and CoO powder. Atomic force microscopy measurements also monitored a reduction in surface roughness during CoO ALE. These studies reveal that alternating changes in oxidation state and crystal structure occur during the sequential Hacac and O3 exposures that define CoO thermal ALE.

Revealing the interlayer orientations for bilayer graphene grown on hexagonal boron nitride by c-AFM measurement

Owing to its excellent properties in optical and electronic applications, twisted bilayer graphene (TBG) has attracted extensive research attention. As an encapsulation layer, hexagonal boron nitride (h-BN) is indispensable for fabricating TBG devices. Because h-BN and graphene exhibit similar lattice structures, TBG on h-BN exhibits periodic moiré patterns, which enable interlayer orientations to be revealed for bilayer graphene on h-BN. Herein, we used two-step chemical vapor deposition to synthesize TBG exhibiting multiple twist angles on h-BN. Conductive atomic force microscopy measurements revealed that the conductivity distribution was different for the graphene/h-BN and TBG moiré patterns. Using the characteristics of the moiré patterns formed by these layers, h-BN and graphene interlayer orientations were precisely determined. This provides a feasible method for investigating the turbostratic arrangement of few-layer van der Waals heterostructures.

Self-Powered Mechanical Energy Sensor Application of SnO2/Ag and PMMA/ITO Nanocomposites via Triboelectric Effect

The triboelectric nanogenerator is a state-of-the-art device for addressing the growing problem of meeting the world's ever-increasing energy needs by converting mechanical energy into electrical energy. Using the popular semiconductor SnO2 nanostructured thin films as a triboelectric layer over contact regions, as opposed to polymers with lesser performance, increases the output power and life time of nanogenerators. In order to design a triboelectric nanogenerator, deposited thin film SnO2 is used as a friction layer with Ag electrode after heat-treatment at 623 K with a contrary layer of PMMA poly (methyl-methacrylate) with ITO electrode. The structural and electrical properties were analyzed by using scanning electron microscopy (SEM), electro-impedance spectroscopy (EIS) and atomic force microscopy (AFM) measurements. The increased output power of the triboelectric nanogenerator is attributed to the nanoscale PMMA contact charge created by tunneling electrons in the SnO2/Ag nanocomposite thin film layer. Due to its proximity to the PMMA/ITO surface, the SnO2/Ag layer causes electron field emission, and tapping the SnO2/Ag layer may result in electron cloud overlap. Similar to a semiconductor/insulator interface, the Fermi level of SnO2 plays a crucial role in electron transport. The system efficiency stated as a touch detector in a conventional keyboard that generates its own power is revealed in part by an analysis of its operating state up to the 4V.

Investigation of CVD Growth of 2D MoS2 on MXene Structures with Photoluminescence Mapping and Fluorescence Lifetime Imaging Microscopy

Molybdenum disulfide (MoS2) and molybdenum carbide (Mo2C) are 2D materials with unique properties that make them suitable for electronic and optoelectronic applications. MoS2 is known for its high optical quantum yield and strong light–matter interaction, while Mo2C has metallic properties and is a member of the relatively new class of 2D materials called MXenes. In this research, a new heterostructure is obtained by growing MoS2 directly on Mo2C for the first time using chemical vapor deposition method. This novel hybrid structure changes the interlayer interaction and excited‐state dynamics, thereby increasing material diversity. The structure is characterized using Raman spectroscopy and atomic force microscopy, while photoluminescence (PL) and fluorescence lifetime imaging microscopy measurements are used to examine exciton motions. This study shows that the thickness of the hybrid structure is directly proportional to the frequency difference between the E2g and A1g modes, and inversely proportional to the PL intensities. The hybrid structure displays distinct exciton transitions due to the metallic effect and a longer fluorescence lifetime when compared to the bare monolayer of MoS2. The introduction of this novel hybrid structure with its optical properties holds great potential in opening up new avenues for optoelectronic device applications.

Crystal orientation dependent spin pumping in a Bi0.1Y2.9Fe5O12/Pt interface

Ferromagnetic resonance (FMR) based spin pumping is a versatile tool to quantify the spin-mixing conductance and spin-to-charge conversion (S2CC) efficiency of ferromagnet–normal metal (FM/NM) heterostructures. The spin-mixing conductance at the FM–NM interface can also be tuned by the crystal orientation symmetry of epitaxial FM. In this work, we study the S2CC in epitaxial bismuth-substituted yttrium iron garnet (Bi0.1Y2.9Fe5O12) thin-film Bi–YIG (100 nm) interfaced with heavy metal platinum (Pt, 8 nm) deposited by pulsed laser deposition on different crystal orientations of Gd3Ga5O12 substrates, i.e. [100] and [111]. The crystal structure and surface roughness characterized by x-ray diffraction and atomic force microscopy measurements establish epitaxial Bi–YIG [100] and Bi–YIG [111] orientations, and atomically flat surfaces, respectively. The S2CC quantification was realized using two complementary techniques, namely (i) FMR-based spin pumping and the inverse spin Hall effect (ISHE) at GHz frequencies and (ii) temperature-dependent spin Seebeck measurements. The FMR-ISHE results demonstrate that the [111]-oriented Bi–YIG/Pt sample shows significantly higher values of spin mixing conductance ((2.31 ± 0.23) × 1018 m−2) and spin Hall angle (0.01 ± 0.001) as compared to the [100]-oriented Bi–YIG/Pt. Longitudinal spin Seebeck measurements reveal that the [111]-oriented sample has a higher spin Seebeck coefficient (106.40 ± 10 nV mm−1 K−1). The anisotropic nature of the spin-mixing conductance and spin Seebeck coefficient in the [111] and [100] orientations are discussed using the magnetic environment elongation along the surface normal or parallel to the growth direction. Our results aid in understanding the role of crystal orientation symmetry in S2CC-based spintronics devices.

Direct-current output of silicon–organic monolayer–platinum Schottky TENGs: Elusive friction-output relationship

Triboelectric nanogenerators (TENGs) are an emerging energy harvesting technology able to convert ubiquitous mechanical energy into electricity. Friction, static charging and flexoelectricity are all involved in the mechanism underpinning TENG operation, but their relative contribution has remained elusive. Here we used dynamic and static conductive atomic force microscopy (C-AFM) measurements on monolayer-modified silicon crystals to detect evidence of a relationship between friction and zero-bias current, and between pressure and the direction of the putative flexovoltage. We demonstrate that a static electricity-related tribovoltage is probably responsible for a friction excess, and that surprisingly this friction excess is found to be dependent on the doping level and type of the silicon substrate. Such friction excess is however no longer measurable once current is allowed to flow across the junction. This observation points to an electrostatic origin of friction in silicon-based Schottky TENGs, and suggests that the zero external bias DC current is at least in part an electronic flow to neutralize static charges. Further, the sign of the zero-bias current, but not its magnitude, is independent of the semiconductor doping type, which is again suggestive of surface statics being a main contributor to the zero-bias output rather than exclusively a space-charge effect. We also reveal the presence of a junction flexovoltage under pressures common in AFM experiments (GPa), even for negligible lateral friction. In a static Pt–monolayer–n-type Si junction the flexovoltage carries the same sign as the tribovoltage, and can reach such magnitude to overwrite external voltages as high as 2 V. The immediate implication is that the flexovoltage is likely to have i) a strong contribution to the zero-bias output of a n-Si Schottky TENG, ii) a negative effect on the output of a p-Si TENG, and iii) its detection can be straightforward, as we discovered that flexoelectricity manifests as an “inverted diode”: a n-type Si–platinum diode with negligible current even when the n-type material is negatively biased as long as the “static” diode remains under a large normal pressure.

Design of thermo-responsive cell culture dishes using poly(N-isopropylacrylamide)-block-polystyrene copolymers for cell sheet technology

The main objective of this work was to assess the cell sheet fabrication of a newly designed thermo-responsive polymer. Thermo-responsive diblock copolymers of poly(N-isopropylacrylamide)-block-polystyrene (PNIPAM-b-PS) with different block ratios were synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. The prepared copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance and gel permeation chromatography techniques in terms of molecular weight and composition. Physical adsorption was employed to prepare thermo-responsive films. Employing atomic force microscopy (AFM) and water contact angle (WCA) measurements, we found that the PNIPAM-b-PS diblock copolymer coatings showed a temperature-triggered phase transition in water through the reversible hydration of PNIPAM segments. Thermo-responsive PNIPAM-b-PS coatings were utilized as functional substrates for human dermal fibroblasts (HDFs) adhesion and detachment. By adjusting PNIPAM to PS segments ratio, HDFs successfully detached from the PNIPAM-b-PS spin-coated tissue culture polystyrene (TCPS) substrates in a temperature-induced manner.

Controllable nitrogen doping of MOCVD Ga2O3 using NH3

We report on the controllable nitrogen doping of β-Ga2O3 as a deep acceptor dopant using ammonia diluted in nitrogen (NH3/N2) as a source of active nitrogen in the metal organic chemical vapor deposition epitaxy. The effects of the NH3/N2 flow rate and substrate temperature on the incorporation efficiency, reproducibility, and controllability of N doping into Ga2O3 were studied using secondary ion mass spectrometry measurements. With the increase in the NH3/N2 molar flow rate from ∼2 × 10−8 to ∼2 × 10−6 mol/min, the N impurities incorporated into the β-Ga2O3 increased linearly from ∼1 × 1018 to ∼2 × 1020 cm−3. At low substrate temperatures (<800 °C), hydrogen was incorporated into the film accompanying nitrogen with comparable concentrations. Despite this, the current–voltage measurements showed that the N and H co-doped films were resistive with a measured resistance of >70 MΩ for a film grown with [N] ≈ [H] of ∼8 × 1018 cm−3. X-ray on-axis (020) and off-axis (111) rocking curve ω-scans and atomic force microscopy measurements show no influence of NH3/N2 dopant on the structural and surface quality of the films. However, the presence of H promoted the growth of (110) and (1¯10) facets elongated along the [001] direction. At high growth temperatures (≥950 °C), the H concentration in the films was reduced by nearly ∼10×, but with a slight increase in the concentration of N. The results show that controllable and repeatable nitrogen doping into β-Ga2O3 can be achieved using ammonia to obtain deep acceptor doping or compensation needed for device engineering in β-Ga2O3-based power electronic devices.

Correlation between the Humidity-Dependent Surface Microstructure and Macroconductivity of Anion Exchange Membranes.

Anion exchange membrane (AEM) fuel cells have gained significant interest in recent years due to their promising applications in cost-effective and environmentally friendly energy conversion. Among various factors that affect their performance, water content plays an important role in the conductivity and stability of AEMs. However, the effect of the hydration level on the microstructure of AEMs and the correlation between the microstructure and macroconductivity have not been systematically investigated. In this work, four AEMs, quaternary ammonia polysulfone, quaternary ammonia poly(N-methyl-piperidine-co-p-terphenyl) (QAPPT), and bromoalkyl-tethered poly(biphenyl alkylene)s PBPA and PBPA-co-BPP, have been studied by atomic force microscopy and electrochemical impedance spectroscopy to elucidate the correlation between the humidity-dependent surface microstructure and macroconductivity of the AEMs. We obtained phase images by atomic force microscopy and identified hydrophilic and hydrophobic domains by fitting the distribution curve of phase images, which reasonably distinguishes hydrophilic domains from hydrophobic domains of the membrane surface, and thus, the surface hydrophilic area ratio and average size could be quantitatively analyzed. The conductivities of the membranes were then measured by electrochemical impedance spectroscopy at various humidities. The joint results from atomic force microscopy and electrochemical measurements help clarify the effect of the hydration level on the microphase separation and ionic conduction of the membranes.