Dr. Janaki R.R. Alavalapati, Dean
School of Forestry & Wildlife Sciences
3301 Forestry and Wildlife Building
602 Duncan Drive
Auburn, Alabama 36849-3418
Auburn University School of Forestry and Wildlife Sciences Fall Seminar Series Presents:
Dr. Ilari Filpponen, Assistant Research Professor, Alabama Center for Paper and Bioresource Engineering, Department of Chemical Engineering, College of Engineering, at Auburn University who will give a talk entitled, Tailoring the surface wettability of cellulose-based paper/nanopaper via novel photo-induced thiol-ene and thiol-yne reactions: Towards electronic and microfluidic applications.
Seminar is held at 11 a.m. in Conference Room 1101 in the SFWS Building, 602 Duncan Drive, Auburn, AL.
Films prepared from cellulose nanofibrils (CNF) have recently been considered as promising substrates for the utilization in electronic devices including displays, transistors, organic light-emitting diodes (OLEDs), touchscreens, lithium ion batteries, solar cells, transparent conductive electrodes and antennas. However, a significant drawback for the use of CNF films in such applications is their high sensitivity to moisture. In this work, a novel and facile process to tailor the wettability of CNF film was developed. Firstly, transparent and reactive porous silicone brush-like nanolayers were introduced onto the CNF film surface by polycondensation of trichlorovinylsilane. Next, the pre-modified CNF films were converted superhydrophobic by introducing low surface tension thiolated fluorine and alkyl molecules via thiol-ene chemistry. Water contact angles (WCA) of 167° and WCA hysteresis < 3° were determined and found to change little after extensive rubbing cycles.
Moreover, it is demonstrated that the micropatterning of cellulose paper/nanopaper can be achieved by using a novel and highly-effective thiol-yne click reaction. Firstly, the paper/nanopaper was functionalized with 4-pentynoic acid via well-known and scalable esterification procedure. Degrees of substitution (DO) of 0.2 and 0.3 were obtained for the paper and nanopaper, respectively. Next, the alkyne-bearing cellulose substrate was subjected to photo-induced click reactions with various thiol-containing molecules to yield either hydrophobic or hydrophilic cellulose surfaces. Finally, micropatterning of the cellulose surfaces was demonstrated by using a photomask-assisted approach. Scanning electron microscopy (SEM), contact angle measurements (CAM) and X-Ray photoelectron spectroscopy were applied to characterize the main morphological and chemical features of the produced materials. Main results and possible applications for such systems will be discussed.
Dr. Ilari Filpponen gained his Master’s degree (2003) from University of Helsinki, Finland majoring in organic chemistry, and his PhD degree (2009) from North Carolina State University (NCSU) with research on production and chemical modifications of cellulose nanocrystals. In 2009-2010 he conducted postdoctoral studies at the NCSU after which he joined the Department of Forest Products Technology, Aalto University, Finland. In 2016, he started as an assistant research professor at Auburn University (joint appointment between SFWS & CHEN). He is currently performing research on chemical functionalization of cellulosic substrates by using different chemistries, with special emphasis on Click chemistry based approaches. His research targets on developing value-added products from renewable woody biomass. To date, he has authored and co-authored 40+ peer-reviewed publications and delivered 30+ presentations in domestic and international conferences.