Laser-induced nanocarbon formation for tuning surface properties of commercial polymers Angela J. McComba, Moataz Abdulhafeza and Dr. Mostafa Bedewya NanoProduct Lab, Department of Industrial Engineering University of Pittsburgh, PA, USA a
Angela McComb is a sophomore undergraduate researcher (SSOE Fellow) in the Industrial Engineering department at the University of Pittsburgh. She is pursuing a degree in Industrial Engineering. Angela McComb
Moataz Abdulhafez is a PhD student at the Industrial Engineering department at Pitt. His research interests include laser material processing and in-situ characterization of nanomaterials. Moataz Abdulhafez
Dr. Mostafa Bedewy is an Assistant Professor of Industrial Engineering, Chemical & Petroleum Engineering, and Mechanical Engineering & Materials Science at the University of Pittsburgh, where he leads the NanoProduct Lab. Before that, he worked as a Postdoc at Dr. Mostafa Bedewy the Massachusetts Institute of Technology (MIT) in the area of bionanofabrication with Professor Karl Berggren in the Research Lab for Electronics. Also, he was previously a Postdoc at the MIT Laboratory for Manufacturing and Productivity, working with Professor John Hart on in situ characterization of carbon nanotube growth. In 2013, he completed his PhD at the University of Michigan in Ann Arbor, where he worked with Professor Hart on studying the population dynamics and the collective mechanochemical factors governing the growth and self-organization of filamentary nanostructures. He holds a Bachelor’s degree (honors) in Mechanical Design and Production Engineering (2006) and a Master’s degree in Mechanical Engineering (2009), both from Cairo University.
Significance Statement
Laser-induced nanocarbon (LINC) is a directly graphitized carbon nanomaterial on polyimide using laser irradiation. It has high potential for applications in antibacterial and antifouling surfaces. We demonstrate that controlling the laser parameters enables tuning the surface properties of LINC.
Category: Experimental research
Keywords: Laser-induced nanocarbon (LINC), Tunable properties, Laser writing, Nanocarbon
68 Undergraduate Research at the Swanson School of Engineering
Abstract
The manufacturing of flexible materials with patterned functional nanostructures is required for wearable electronics and conformal devices. Laser-induced nanocarbon (LINC) is a typically porous material prepared by direct laser writing with an infrared laser on polymers like polyimide in ambient atmosphere. The resulting material is graphitic and hence conductive, making it suitable for applications in broad fields, such as microfluidics, sensors, and electrocatalysts. This paper aims to expand the range of surface properties for LINC by tuning laser processing parameters. While it was previously shown that different wetting behavior of LINC can be achieved by lasing in inert atmospheres, we uniquely fabricate hydrophobic and hydrophilic LINC by lasing in air, which underlie the simplicity, scalability, and cost-effectiveness of our process. We demonstrate that by varying laser speed, power, and line-to-line gap sizes, considerable changes in water contact angle can be obtained. Upon examining tensiometer, optical, and scanning electron microscopy (SEM) images, it is clear that different surface properties are due to the different morphologies of LINC. Additionally, it becomes evident that increasing gap sizes leads to an increase in contact angles and thus an increase in the hydrophobicity of the surface. The results demonstrate that simple changes to the lasing parameters, the sample hydrophilicity and hydrophobicity can be controlled without special environment control setups. The results also provide insight into the underlying mechanisms behind the various wetting behaviors of LINC.
1. Introduction
The applications of commodity polymers are ubiquitous in almost all aspects of modern life. Recently, it has been shown that nanoscale graphitic structures can be synthesized through the lasing of polyimide, a popular commodity polymer, with commercially available low-cost IR lasers [1]. These laser-induced nanocarbon (LINC) structures have been shown to exhibit excellent electrical and thermal conductivity as well as high surface area [1]. In addition, different morphologies have been observed at the microscale for LINC material, ranging from porous to fibrous [2]. Accordingly, wide-reaching potential applications of LINC such as anti-fouling [3], anti-icing [4] and antimicrobial [5] surfaces have been investigated. Recent research has shown that LINC surface properties depend on lasing parameters such as laser power and speed [6]–[8]. For example, it was shown that by changing the lasing environment, namely the process gas, the contact angle between water droplets and LINC surfaces can be switched between superhydrophobic (>150°) and superhydrophilic[8]. To fully exploit this feature, we generate nanostructured carbon directly on the surfaces of the commercial Kapton films by surface lasing with the objective of tuning surface properties and morphology in a large range of contact angles based on changing laser power, speed, and line-to-line gap in the LINC process. We explore the lasing parameter space to achieve control over the resulting contact angle of direct written LINC areas. Here, we test the hypothesis of whether it is possible to achieve contact angle control by only changing the lasing parameters in an air
