DESIGNING AN AFFORDABLE DIP-COATING SYSTEM WITH USER-FRIENDLY SOFTWARE FOR LAYER-BY-LAYER NANOCOMPOSITE FABRICATION

Abstract

To address the challenge of providing accessible hands-on experiences in advanced materials science, this study reports the design, construction, and operation of a low-cost dip-coater. Built from inexpensive mechanical and electronic components, including recycled parts from a computer digital versatile disc (DVD) drive, a step motor, a liquid crystal display (LCD), and an Arduino platform, this instrument offers a practical platform for fundamental concepts in nanomaterial fabrication, self-assembly, and spectroscopic analysis. The dip coater operates over a wide speed range of 0.44-2.4 cm min^-1 and features a user-friendly HTML page through a Wi-Fi connection. It was demonstrated its application by fabricating reproducible layer-by-layer nanocomposites based on the self-assembly of Au nanoparticles on poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) thin films. Characterization using UV-Vis spectroscopy, surface-enhanced Raman spectroscopy (SERS), and atomic force microscopy (AFM) allows students to investigate critical material properties and validate the assembly processes.

Keywords:
laboratory equipment; laboratory apparatus; Arduino; layer-by-layer; UV-Vis; SERS.

INTRODUCTION

Providing students with hands-on experience in advanced materials science, particularly in areas like thin-film fabrication and nanomaterials, is often hindered by the high costs of specialized laboratory equipment, such as dip-coaters, especially in developing countries.¹ This financial barrier restricts opportunities of the students to engage directly with modern research techniques and develop essential practical skills.

Thus, open-source microcontroller boards, such as Arduino, offer a viable option for building cost-effective and accessible laboratory equipment. This approach not only democratizes access to scientific tools but also provides invaluable interdisciplinary learning opportunities. Previous reports²-¹⁰ have demonstrated the feasibility of inexpensive, do-it-yourself (DIY) designs and assembly of laboratory instruments using microcontrollers, such as magnetic stirrers, thermometers, potentiostats, titrators, gas sensors, pH sensors, and centrifuges. The open-source nature of Arduino software enables users to tailor and enhance their devices to meet specific needs at a low cost.

Beyond the economic advantages, the integration of DIY instruments is supported by current pedagogical research in chemical education.¹¹ Traditional, prescriptive laboratory models often fail to foster a deeper conceptual understanding, critical thinking, or scientific reasoning. In contrast, involving students in the construction and troubleshooting of DIY analytical instruments allows them to examine each individual component, leading to a deeper theoretical and practical understanding of the underlying chemistry.¹² This hands-on, problem-based approach shifts the responsibility of the learning experience from the instructor to the students, which increases student engagement, autonomy, and ownership of their work. Consequently, the DIY construction of a dip-coater serves as an educational strategy that facilitates the development of transferrable skills, preparing students more effectively for scientific research.¹³,¹⁴

Among thin-film fabrication techniques, dip-coating is particularly valuable because of its simplicity and versatility, allowing the production of homogeneous and reproducible films with tunable thicknesses and uniformity.¹⁵-¹⁷ This technique provides a means to teach fundamental concepts in materials science, including surface tension, fluid dynamics, and the role of withdrawal speed in thin-film formation. During the dip-coating process, the material self-organizes as the substrate is removed from the solution (Figure 1). Understanding the self-assembly process, governed by parameters such as the rate of evaporation of the solvent (J_e), the force of surface tension in the meniscus (J_s), and the flux of particles (J_p) offers deep insights into material behavior at interfaces.¹⁸

Figure 1
Schematic representation of the dip-coating process

The inherent abstract nature of nanoscience, where matter behaves unconventionally at the nanoscale and cannot be directly “seen” or “handled” without specialized tools, makes hands-on learning particularly important.¹⁹ Direct experiences with nanomaterials and their phenomena are essential for challenging macroscopic intuitions of the students and facilitating a deeper understanding of size-dependent properties.²⁰ Furthermore, engaging students in practical activities has been shown to significantly improve their attitudes toward chemistry by making learning “real” and relevant, fostering greater effort and deeper engagement. Integrating nanomaterials into chemistry curricula is essential because these materials exhibit unique properties and diverse applications not seen in bulk materials. Noble metal nanoparticles, such as gold nanoparticles (AuNPs), are particularly interesting due to their distinctive optical, electronic, and magnetic properties compared to isolated atoms or bulk materials.²¹,²²

A key phenomenon exhibited by these nanoparticles is localized surface plasmon resonance (LSPR), which arises from the coherent collective oscillation of conduction electrons within the particle when exposed to electromagnetic radiation.²³,²⁴ This LSPR creates remarkably enhanced electric fields in localized regions, particularly in small clusters of metallic nanoparticles, known as “hotspots”. These hotspots are central to surface-enhanced Raman scattering (SERS), where molecules adsorbed onto the surfaces of these plasmonic structures undergo substantial amplification of their Raman scattering signals.²⁵ The degree of SERS enhancement is influenced by various characteristics of the AuNPs, including their dielectric properties, size, shape, and interparticle distance. Thus, the ability to control the assembly of AuNPs, as enabled by our dip-coater, directly impacts these fundamental optical and spectroscopic properties, providing a powerful platform for teaching principles of spectroscopy and sensing.²⁶

To bridge the gap between theoretical understanding and practical application, and to provide accessible hands-on experience in nanomaterial fabrication, we report the design, construction, and operation of a low-cost, open-source dip-coater. While an affordable Arduino-based dip-coater has been previously reported,¹¹ the system proposed herein introduces specific technical advances. Although previous instruments operate via a physical digital control panel utilizing an Epson printer stepper motor and achieves a speed range of 0.1-6.0 mm s^-1 (6.0-36.0 cm min^-1), our system repurposes components from a computer DVD drive connected to a Wemos D1 mini board (ESP8266), providing a more specific speed range (0.44 2.4 cm min^-1) optimized for controlled nanometric self assembly. Furthermore, our equipment introduces wireless operation through a user-friendly HTML interface via Wi-Fi, replacing the need for direct manual contact with a physical keypad during operation. Also, unlike previous methods that relied on spin-coating for the fabrication of layer-by-layer composites, our work demonstrates the novel use of this accessible dip-coater for the reproducible layer-by-layer fabrication of AuNP/poly(styrene-block-2-vinylpyridine) (PS b P2VP) nanocomposites.²⁷-²⁹ These integrated hardware and software features significantly enhance its utility for student exploration and experimentation. We validated the performance of the instrument by fabricating and characterizing these nanocomposites using UV-Vis spectroscopy, SERS, and atomic force microscopy (AFM), demonstrating its potential as a robust educational tool for teaching materials science and analytical techniques.

EXPERIMENTAL

Construction of the dip-coater

The design and construction of the dip-coater prioritized cost-effectiveness and the use of readily available components, including recycled parts. The assembled dip-coater and its 3D model are shown in Figure 2.

Figure 2
Dip-coater structure: (a) real, (b) 3D model, (c) 3D model rendered

The following components were used for the dip-coating equipment.

Mechanical components

• - Metal base (width = 13.6 cm, height = 5.9 cm, length = 33.2 cm).

• - Two sliders and two rods provided a maximum amplitude of 11.9 cm for vertical movement.

• - A one-step motor (e.g., NEMA 17 or similar, commonly found in 3D printers or DVD drives) connected to a screw.

• - One 3D-printed gear (diameter = 6.7 cm).

• - Two alligator clips were used for substrate attachment.

• - Additional support parts were fabricated using a three-dimensional (3D) printer.

The 3D structural components were fabricated from poly(lactic acid) (PLA) without the need for support structures. Slicing was performed using Ultimaker Cura software, version 5.12 (Ultimaker B.V., Netherlands, 2011), with a 0.15 mm layer resolution, a 10% gyroid infill, three perimeter walls, and three top and bottom layers. The total manufacturing time for the complete set was 4 h and 17 min, consuming approximately 40 g of filament. The open-source 3D model of this part is available for replication at Zenodo.³⁰

Electronic components

• - A dual-voltage power supply was repurposed from a used computer digital versatile disc (DVD) drive, which provides independent outputs of 5 V (2.0 A max) for the microcontroller logic and 12 V (2.0 A max) for the stepper motor translation.

• - An A4988 stepper motor driver is essential for controlling the precise movements of the step motor.

• - A Wemos D1 mini board equipped with an ESP8266 Wi-Fi chip served as the central microcontroller for system management and Wi-Fi connectivity.

• - A 16 × 2 liquid crystal display (LCD) integrated with an I2C module (PCF8574) was used to provide real-time operational feedback to the user, such as the IP address for control access.

• - A soldering board and various wires for circuit assembly were used.

The assembly procedure of the device consists of first securing the vertical rods and the lead screw onto the structural metal base, followed by the alignment of the sliders and the installation of the 3D-printed gears onto the stepper motor shaft. Once the mechanical core is aligned to ensure smooth, friction-free vertical displacement, the electronic components are integrated. The Wemos D1 mini, the A4988 driver, and the I2C LCD interface are soldered onto the universal board according to the circuit logic, and the entire control assembly is connected to the repurposed DVD power supply. A comprehensive electronic schematic outlining the explicit pin connections between these components (Figure 1S, Supplementary Material), where “GND” refers to the signal ground of individual components and “Earth” denotes the ground of the external power supply.

The Arduino IDE (Integrated Development Environment), version 2.3.9 (Arduino, Italy, 2005). was used for programming. The code was developed in Wiring language,³¹ based on the C/C++ languages. The following libraries were used to create the application: (i) Arduino Code: WebserverMoyra2022_AP.ino; (ii) Web interface: data/index.html, index1.h, index2.h, index3.h; (iii) Wi-Fi Connection: we used public libraries available in the Arduino repositories³² ESP8266WiFi.h, WiFiClient.h, ESP8266WiFiMulti.h, ESP8266mDNS.h, ESP8266WebServer.h; (iv) in order to show the WIFI-IP connection information we used the following libraries available in Arduino repositories³³ Wire.h and LiquidCrystal_I2C.h. The source code that we developed in order to control the dip-coater is available at Zenodo repository.³⁰ The connection between the computer and WEMOS D1 mini was established via a USB cable.

Fabrication of layer-by-layer thin films

The dip-coater was used to fabricate layer-by-layer thin films of AuNPs adsorbed onto PS-b-P2VP copolymer matrices.

Materials

Poly(styrene-block-2-vinylpyridine) copolymer (M_n 265,000 g mol^-1, polydispersity 1.30, PS:P2VP ratio 1250:1285) was obtained from Polymer Source, Inc. (Quebec, Canada). Tetrachloroauric acid (HAuCl₄) was purchased from Sigma-Aldrich, USA. All solvents were supplied by Sigma-Aldrich, USA, and used as received.

Gold nanoparticle preparation

Gold nanoparticles were prepared using the established Frens method.³⁴ Briefly, 1 mL of HAuCl₄ (2.9 × 10^-3 mol L^-1) was added to 100 mL of deionized water and heated to a reflux. Subsequently, 1 mL of a 1% sodium citrate solution was rapidly added, leading to the formation of a vibrant red colloidal suspension in a few minutes.

Substrate preparation

Glass slides (1 cm × 3 cm) were meticulously cleaned to ensure reproducible film deposition on them. The cleaning procedure involved successive ultrasonic baths in ethanol, isopropyl alcohol, and acetone (10 min each), followed by immersion in piranha solution, H₂SO₄/H₂O₂ 7:3 (this solution is highly corrosive and should be handled with caution) for 30 min. After thorough rinsing with deionized water, the substrates were dried under ambient conditions.

Dip-coating procedure for bilayer fabrication

The layer-by-layer fabrication process enables controlled growth. The procedure consisted of the following steps for each bilayer:

(i) Polymer layer deposition: glass slides were vertically immersed into a 0.5 wt.% PS-b-P2VP solution (prepared by dissolving the block copolymer in toluene and stirring overnight) at a constant rate of 2.4 cm min^-1. A 15 min pause was allowed for initial film stabilization, followed by withdrawal at the same rate.

(ii) Immersion in water: the polymer-coated slides were immersed in deionized water to induce polymer reconstruction.³⁵

(iii) AuNP adsorption: the polymer-coated slides were vertically immersed in the colloidal AuNP solution at 2.4 cm min^-1. An immersion pause of 1 h was found to optimize nanoparticle adsorption, as determined by preliminary experiments that varied the pause times between 30 min and 1 h. The slides were then withdrawn at the same rate.

(iv) Rinsing and drying: prepared substrates were rinsed with deionized water to remove excess of AuNP that were not adsorbed into the polymer matrix, and dried under ambient conditions. This procedure was repeated multiple times to achieve the desired number of bilayers.

Characterization of nanocomposites

The fabricated nanocomposites were characterized using techniques fundamental to materials science. After each deposition step (to monitor self-assembly), the following analyses were performed.

UV-Vis spectroscopy

UV-Vis absorption spectra were obtained using a Shimadzu UV 1800 spectrophotometer (Japan) equipped with a 1.0 cm silica cell. Spectra were recorded in the range of 340-1100 nm with a resolution of 0.2 nm. Thin films on glass slides were fixed in a sample holder, using a clean glass slide as a reference.

SERS spectroscopy

SERS spectra were acquired using a Bruker SENTERRA spectrometer (Germany) with a 632.8 nm laser source at a maximum power of 10 mW. To facilitate the SERS analysis, the layer-by-layer thin film samples were immersed in Nile Blue (NB) dye (1 × 10^-4 mol L^-1) for 12 h, extensively washed with deionized water, and dried under vacuum. SERS mapping of the characteristic 594 cm^-1 band of Nile Blue, corresponding to the phenoxazine ring vibration,³⁵ was performed within a 50 × 50 μm scan range, divided into a 10 spectra × 10 lines acquisition grid.

Atomic force microscopy (AFM)

AFM topographical images were obtained in tapping mode using a Multimode8-HR atomic force microscope (Bruker, USA) with ScanAsyst-Air model cantilevers (spring constant 0.4 N m^-1) (LNNano/CNPEM, Campinas, Brazil). The images were post-processed using the SPM software Gwyddion, version 2.71 (David Nečas and Petr Klapetek, Czech Metrology Institute, Czech Republic, 2004).

RESULTS AND DISCUSSION

This section presents the cost assessment, performance validation of the low-cost dip-coater and demonstrates its utility fabrication and characterization of layer-by-layer gold nanoparticle nanocomposites.

Hardware cost assessment

The economic feasibility of the developed dip-coating platform is a primary advantage for resource-limited laboratories. Table 1 details the cost breakdown of the individual components required for the assembly of the proposed system. The total cost of the DIY platform remains under fifty USD, representing a fraction of the investment associated with commercial equipment. For comparison purposes, an entry-level commercial dip-coater typically ranges from 3,000 to 4,000 USD. This substantial reduction in cost validates the accessibility and financial viability of the approach implemented in this study.

Table 1
Cost breakdown of the proposed DIY dip-coater components

Component / system	Estimated cost / USD
Microcontroller (Wemos D1 mini)	$ 5.00
Stepper motor (recycled) & drive pulley	$ 0.00
LCD display	$ 3.78
A4988 stepper motor driver	$ 4.80
Rotary and vertical stage (3D-printed parts)	$ 10.00
Structural hardware (screws, rods, metal base)	$ 15.00
Miscellaneous (wires, clips, connectors)	$ 5.00
Total proposed system cost	$ 43.58

Estimation of the velocity

The speed calibration process was carried out using computer vision tools.³⁶ In general, calibration was performed by temporarily attaching a millimeter-scale ruler next to the central motion device. Using a tripod and smartphone, the downward movement for different step mm^-1 values of the stepper motor was obtained. The Python code developed to obtain video frames, calculate time intervals, and determine pixel positions for each image is available in the Zenodo repository.³⁰ Based on these datasets, the minimum velocity was determined to be V_min = (0.44 ± 0.05) cm min^-1, and the maximum velocity was estimated to be V_max = (2.40 ± 0.05) cm min^-1.

This operational speed window represents the physical boundaries of the repurposed DVD drive stepper motor under the implemented micro-stepping electronic configuration. Coupled with the two structural rods that provide a maximum vertical movement amplitude of 11.9 cm, these dimensions define the strict physical capability of the hardware. Although this maximum speed represents a translation limit compared to broader setups, it serves as an inherent design advantage for controlled nanoscale self-assembly. Furthermore, keeping the hardware limited to this slow speed range guarantees that the motor operates at its optimal torque, preventing step loss and keeping the critical withdrawal phase completely free of macro-vibrations across the entire vertical displacement course. Also, the electrical stability of the system played a key role in maintaining this smooth, vibration-free motion. The repurposed dual-voltage power supply delivered high voltage stability with negligible ripple throughout the experiments. This electrical stability ensured that the current capacity easily satisfied the demands of the A4988 driver, preventing voltage drops or high-frequency electrical noise interference that could otherwise lead to motor step loss or mechanical jitter during the critical substrate translation phases.

The Python programming language³⁷ was employed with the following libraries: Numpy³⁸ was used to perform mathematical computations, and OpenCV³⁹ was used to obtain all frames from each video. The time interval between images was obtained by classifying the images with an integer that identifies the image in time and knowing the frame rate of the video. Next, the number of pixels associated with 1 mm from the ruler image and the central bar’s pixel position in each image were measured to calculate the velocity.

Operation of the dip-coater

To operate the dip-coating equipment, the initial step involves enabling Wi-Fi sharing on a device (such as a mobile phone or computer) to accept the internet access of other devices. When the equipment is powered on, it automatically connects to the network, and the IP address “172.20.10.2” is displayed on the screen. When the HTML page is accessed, the following information for controlling the equipment is shown: the number of turns, speed, options to move up or down, and data transmission. Once the user has set the parameters, including the number of turns and speed, they should send the data to the equipment and choose whether to move up or down.

Preparation of layer-by-layer AuNP/PS-b-P2VP thin films

The production of layer-by-layer films of AuNP/PS-b-P2VP by dip-coating was monitored by UV-Vis spectroscopy. Figure 3 shows the UV-Vis extinction spectra for the formation of a single layer composed of PS-b-P2VP and AuNPs. Thin films containing a single layer of PS-b-P2VP were prepared and immersed in a colloidal solution containing AuNPs to investigate the effect of immersion time on nanoparticle adsorption. Various experiments were conducted by varying the immersion period. An extinction band with a maximum at approximately 556 nm, corresponding to the localized surface plasmon resonance (LSPR) of the gold nanoparticles, is observed. As can be observed, there is a rapid increase in extinction from 15 to 45 min, reflecting a diffusion-controlled process driven by the high concentration of vacant coordination sites on the poly(2-vinylpyridine) blocks readily available for interaction with the gold nanoparticles. Between 45 min and 1 h, the adsorption rate noticeably decreases, suggesting that the system is approaching a thermodynamic quasi-equilibrium. This deceleration is attributed to the progressive saturation of the accessible binding sites and the subsequent electrostatic and steric repulsion among the newly arriving gold nanoparticles on the polymer matrix. Therefore, the choice of a 1-hour immersion period represents an optimized parametric plateau that ensures maximum and stable particle density before initiating the subsequent layer-by-layer growth sequences.

Figure 3
UV-Vis spectra of AuNP/PS-b-P2VP films as a function of immersion time in the colloidal solution

Figure 4a shows the UV-Vis spectra for each bilayer deposition in the construction of a layer-by-layer film of AuNP/PS-b-P2VP. An extinction band with a maximum at approximately 556 nm, corresponding to the LSPR of the gold nanoparticles, was also observed. A linear increase (coefficient of determination (R²) = 0.983) in the maximum extinction related to the increase in the number of bilayers is shown in Figure 4b, indicating that the number of deposited nanoparticles increases with the formation of multiple bilayers. This linear behavior indicates reproducible AuNP deposition in each bilayer. Also, this high linearity and deposition reproducibility also serve as an indirect validation of the mechanical stability of the instrument. Although the hardware utilizes repurposed DVD drive components, the controlled operating speed range (0.44-2.4 cm^-1), managed by the A4988 microstepping driver, effectively minimizes macro-vibrations, providing a uniform and repeatable nanometric alignment without the need for high-end commercial systems.

Figure 4
(a) UV-Vis spectra of self-assembled films of AuNP/PS-b-P2VP for each bilayer deposited, where curves 1 through 5 correspond to the sequential deposition of 1 to 5 bilayers, respectively; (b) extinction at 556 nm as a function of the number of bilayers in this film

The fabricated thin films were analyzed using SERS, employing Nile Blue as the molecular probe (the corresponding average SERS spectra are shown in Figure 2S, Supplementary Material). The histogram was constructed by monitoring the intensity of the Nile Blue band at 594 cm^-1, which corresponds to the vibration of the phenoxazine ring,⁴⁰ as a function of the number of bilayers (Figure 5). An increase in SERS intensity with increasing bilayer number was observed, confirming the UV-Vis results.

Figure 5
Histogram of the SERS intensity of the Nile Blue band at 594 cm^-1 as a function of the number of bilayers

To quantitatively analyse the analytical performance of the fabricated nanocomposites, the average SERS enhancement factor (EF) was calculated. Following the rigorous methodology established by Le Ru et al.,⁴¹ the EF was determined by comparing the SERS intensity of the molecular probe adsorbed on the nanostructured film (I_SERS) with its normal Raman intensity obtained from a bulk solution (I_Raman). To provide an accurate estimation, the intensities were normalized to the analyte concentration for each measurement. The EF was calculated using the following Equation 1:

(1) $$\mathrm{EF}=\frac{{\mathrm{I}}_{\text{SERS}}/{\mathrm{C}}_{\text{SERS}}}{{\mathrm{I}}_{\text{Raman}}/{\mathrm{C}}_{\text{Raman}}}$$

where C_Raman and C_SERS are the concentrations of the NB solution in the normal Raman and SERS, respectively.

Thus, the calculated enhancement factors for the assembled films were 6.97 × 10⁴ for 1 bilayer, 2.03 × 10⁵ for 2 bilayers, 2.72 × 10⁵ for 3 bilayers, 3.20 × 10⁵ for 4 bilayers, and 4.79 × 10⁵ for the 5-bilayer film. The corresponding normal Raman spectrum of the bulk reference solution is presented in the Supplementary Material (Figure 3S). These EF values are in agreement with the typical average enhancement ranges reported for nanostructured SERS substrates.⁴²-⁴⁴ These EF values demonstrate that despite the low-cost and DIY nature of the proposed automated dip-coating platform, the resulting nanocomposites deliver an interesting plasmonic performance.

The AFM topographical images of the films following the deposition of the AuNP/PS-b-P2VP bilayers are shown in Figure 6. With the formation of each bilayer, a noticeable change in the morphology of the thin film was observed. Due to the increase in the concentration of the polymer matrix, it is difficult to observe the AuNPs as the number of bilayers increases. However, this result, combined with the UV-Vis and SERS results, indicates a consistent increase in AuNP deposition with the formation of each bilayer. This suggests that in the layer-by-layer fabrication process, more AuNPs are adsorbed in the film as additional layers are added, which is important for developing a substrate with a strong enhancement of the SERS signal.

Figure 6
5 μm × 5 μm AFM topographical images of AuNP/Ps-b-P2VP nanocomposites with an increase in the number of bilayers: (a) 1^st bilayer; (b) 2^nd bilayer; (c) 3^rd bilayer; (d) 4^th bilayer; (e) 5^th bilayer

CONCLUSIONS

In this study, we present the design, construction, and validation of a low-cost dip coater utilizing recycled components from a computer DVD drive and a microcontroller. The fabricated equipment proved to be a reliable system, operating at a speed range of 0.44 2.4 cm min^-1. Through the reproducible fabrication of layer-by-layer gold nanoparticle (AuNP) nanocomposites, confirmed by UV-Vis and SERS analyses (which showed a linear increase in AuNP density), we demonstrated the capability of the dip-coater to produce thin films with high consistency. Furthermore, while this study focused on high-end materials and advanced characterization tools (AFM and SERS) to rigorously validate the mechanical precision of the hardware at the nanoscale, the proposed open-source device can be readily extended to much simpler and cost-effective experimental setups. For instance, this accessible platform can be easily adapted to fabricate uniform transition metal oxide films via straightforward sol-gel methods or to develop alternative layer-by-layer polymeric systems utilizing inexpensive materials, such as polyelectrolyte/clay nanocomposites. These low-cost configurations can be effectively monitored using standard, widespread laboratory techniques. Consequently, the hardware architecture described here highlights the development of a practical, robust, and economical solution for laboratory instrumentation. It serves as an adaptable bridge capable of supporting both advanced materials research and low-budget educational experiences in resource-limited institutions. The open-source design and use of recycled components make this dip-coater an ideal tool for engaging students in interdisciplinary projects. Through its construction and operation, students can gain practical insights into electronics, programming (Arduino, HTML), and the synthesis of advanced functional materials, effectively making cutting-edge materials science more accessible to a wider demographic of science and engineering students.

SUPPLEMENTARY MATERIAL

Supplementary material for this work is available at http://quimicanova.sbq.org.br/, as a PDF file, with free access.

Supplementary PDF

Supplementary PDF

ACKNOWLEDGMENTS

This study was financed in part by the CAPES, Finance Code 001 and FAPEMIG. This research used facilities of the Brazilian Nanotechnology National Laboratory (LNNano), part of the Brazilian Centre for Research in Energy and Materials (CNPEM), a private non-profit organization under the supervision of the Brazilian Ministry for Science, Technology, and Innovations (MCTI). The atomic force microscopy staff are acknowledged for their assistance during the experiments (AFM-27489).

DATA AVAILABILITY STATEMENT

Data should be requested from the corresponding author.

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e-mail: [e-mail]

Executive Editor handled this article:

Júlio S. Rebouças

Publication Dates

• Publication in this collection
  03 Aug 2026
• Date of issue
  2026

History

• Received
  08 Apr 2026
• Accepted
  26 June 2026
• Published
  08 July 2026