Scalable self- assembly of nanoparticles for industrial applications


Recent technological advances have opened up new fields that apply ordered structures of the nano and micro- scales made by assembly of colloidal particles. By applying this fabrication technique, one can achieve intrinsic structures using top-down approaches, such as soft lithography and pre-patterning of substrates. Alternatively, one can employ bottom-up self-organization processes that involved reduced production steps hence have of late become a hot research area. Several of these bottom-up techniques have already been developed, unfortunately, the scalability of some of their aspects to industrial applicable setup have proven to be problematic. To be specific, the aspect relating to the mechanism of mixed colloids size segregation in drying menisci is still hazy and need further investigation. More so, were it possible to study the size segregation with scalable experimental techniques, then it would metamorphose into a future technique of manufacturing complex structures by facilitating the design of the process responsible for binary colloids deposition.

To this end, Texas State University researchers (Sayantan Das, El-Shazly Duraia, Orlin Velev ( North Carolina State University), Maedeh Amiri) led by professor Gary Beall conducted a study with the objective of adapting the convective self-assembly technique, well known for producing highly ordered monolayer structures, to create novel surface patterns using the binary mixture of colloids. They intended to demonstrate that different patterns could be formed, based on the size ratio (Small/Large) of the particles, and particles volume ratio. Their work is currently published in the research journal, Applied Surface Science.

The research method employed commenced with the systematic examination of the effects of size ratio of the particles, volume fraction, and surface tension of the solvents. These examinations enabled the formation of various surface patterns and the understanding of the mechanism behind size-based segregation. Next, the researchers prepared the setup and kept it in a humidity controlled box. Then they undertook a qualitative analysis of the developed film using optical microscopy and videography. Lastly, a quantitative analysis procedure was undertaken where scanning electron microscopy was utilized.

The authors observed that certain binary particle mixtures resulted in spontaneous size based segregation. Moreover, in some cases, they noted that the particle separation occurred along the direction of the meniscus contact line. Consequently, their study revealed that some parameters, namely: particle volume fraction, size differences, surface tension, and the curvature of the meniscus played a crucial factor in the segregation process as well as in determining the width of each of the stripes.

In conclusion, the S. Das et al study presented the development and demonstration of a technique and mechanism for fabricating periodic size-segregated stripe patterns using binary colloidal films. Generally, it was seen that based on both empirical and numerical analysis, a mechanism for size-based segregation of particles via directed self-assembly could be developed. Altogether, this work has presented the periodic size segregated pattern formation by the mere design of industrially scalable process useful for various applications.


Scalable self- assembly of nanoparticles for industrial applications, Advances in Engineering


About the author

Sayantan Das is working as an adjunct faculty at Texas A&M University -San Antonio, received the B.Sc. degree in electrical engineering from West Bengal University of Technology, Kolkata, India, in 2009, the M.Sc. degree in applied mathematics from the University of Texas Pan–American, Edinburg, TX, USA, in 2011, the Ph.D. degree in Material science engineering, and MBA from Texas State University, San Marcos, TX, USA, in 2015. Worked as a Post-Doctoral Fellow at Texas State University (2016) and as a Sr. Process Engineer at SioteX Corp. (2017-2018).

His current research interests at Texas State University, include self-assembly of nanoparticles to create hierarchical structures for sensor applications.

About the author

El-shazly M. Duraia is working as an associate professor at Suez Canal University since 2015 and currently working at Texas state university as visitor scholar. He received his B.Sc. in 1997 and M.Sc. in 2004 from Suez Canal University, Ismailia Egypt. In 2010, he received the PhD degree at Kazakh National University in material science. He has been awarded as a distinguished student during his Ph.D. During his studies for doctor degree he worked as a visiting student at Texas State University in 2009. Afterward, he began his career as a lecturer at Suez Canal University. In 2011, he worked as a visiting scholar at Texas State University for two years.

His research interests are the synthesis and assembling of carbon nanomaterials, and their application in the fields of sensors and catalysis..

About the author

Dr. Gary W. Beall (Texas State University, College of Sciences) has a Ph.D. in Physical Chemistry from Baylor University. Dr. Beall’s first job out of graduate school was at Oak Ridge National Laboratory where he conducted research on the environmental fate of actinides originating from the civilian nuclear fuel cycle. He then moved to industry for 21 years during which he served as researcher, group leader, technical director, and vice president for a number of different companies and also founded his own company. The central theme of the research conducted during this period was applications of surface modified clay nanoparticles in paint, cosmetics, grease, pharmaceuticals, cat litter, water treatment, and polymers.

He has over 120 publications in refereed journals and 48 US patents in his name. Dr. Beall co-edited the first book written on polymer/clay nanocomposites in 2000 and just published the second on the subject in 2011 coauthored with Dr. Clois Powell. Dr. Beall is well known for his work on nanoparticles (especially smectic type of nanoparticles) and their surface modification and application in a multitude of application areas. Recent research interests include low cost synthesis of graphenes and other 2-D systems.

He is currently Regents’ Professor in the Department of Chemistry and Biochemistry, Formosa Endowed Chair, Director of the Center for Nanophase Research, and Associate Director of the Materials Science, Engineering, and Commercialization program at Texas State University. Dr. Beall is also currently serving as a science advisor and adjunct professor for Al-Farabi Kazakh National University, and distinguished adjunct professor for King Abdulaziz University, SA. He is also founder and CTO of Nabaco Inc.


Sayantan Das, El-Shazly M. Duraia, Orlin D. Velev, Maedeh D. Amiri, Gary W. Beall. Formation of periodic size-segregated stripe pattern via directed self-assembly of binary colloids and its mechanism.. Applied Surface Science, volume 435 (2018) page 512–520.

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