'Structure-Property-Relationship of Epoxy and Oxetane Thermosets using Photo-initiated Cationic Polymerization.’
Professor and Director
Chang Y. Ryu
Department of Chemistry and Chemical Biology
New York State Center for Polymer Synthesis
Rensselaer Polytechnic Institute
Troy, New York, USA
Abstract
The design, preparation and characterization of novel UV-polymerized thermosets derived from sustainable feedstocks such as vegetable oils and terpenes will be discussed.
A copolymerization strategy has been employed to tailor the physical properties of thermosets to elucidate the structure-property-relationships of crosslinked thermoset polymers with network structure. It is our goal to study and develop sustainable epoxy/oxetane thermoset resins in a fast, solvent-free and energy-efficient manner using the photoinitiated cationic ring-opening polymerization.
Two model thermoset systems have been studied based on epoxy and oxetane monomers: epoxidized linseed oil (ELO) and “di-oxetane” (DOX). Both systems are suffering from the poor control of polymer network formation, because ELO has a high viscosity and DOX exhibits a long induction period for UV-curing.
The incomplete network formation has led to the formation of UV-cured polymer films and coatings showing a low Tg. In the case of ELO, comonomers of low viscosity and high epoxy equivalent weight have been designed, synthesized, and compared to facilitate the copolymerization of ELO. For the DOX, bio-derived limonene dioxide was copolymerized for use as “kick-starter” to eliminate the long induction time.
Both copolymerization approaches with faster UV curing without induction period allow us to complete room temperature UV-crosslinking with short curing time (< 20 sec) and to produce polymer films and coatings having Tg higher than 100 °C. Temperature-controlled real-time FTIR (RT FTIR) will be used to demonstrate the thermal stability of hydrogen-bonded complex with DOX to reveal the fundamental mechanism for the induction period of DOX in photo-cationic polymerization.
Short-bio of Professor Chang Y. Ryu
Professor Ryu received his B.S. and M.S. degrees from Seoul National University in Korea. Upon earning his Ph.D. (1998) in Chemical Engineering at the University of Minnesota with Tim Lodge, he worked as a postdoctoral researcher in the Materials Research Laboratory at the University of California, Santa Barbara for two years with Ed Kramer.
He joined Rensselaer in 2000 as an Assistant Professor of Chemistry, and was promoted to an Associate Professor with tenure in 2006 and a Full Professor in 2013. He served as an Acting Head of Chemistry and Chemical Biology Department at RPI in 2014-2015, and currently serves as the Director of NY State Center for Polymer Synthesis at RPI.
He has won the NSF CAREER Award (2005), RPI Exploratory Research Award (2002), Mettler-Toledo Thermal Analysis Education Grant (2001), and the Arthur K. Doolittle Award from the American Chemical Society Division of Polymeric Materials Science and Engineering (1998).
In 2007 - 2013, he also serves as a director of the NSF-funded Partnership for International Research and Education (PIRE) Program between US and Korea on interfacially active copolymer materials.
His research focuses HPLC analysis, large-scale separation of block copolymers, photo-initiated cationic polymerization, and sustainable polymers from renewable sources.