The research focus of the Ryu Group is the development of new polymer materials with well-defined structure. Using rheology, scattering and microscopy tools, our research group investigates a number of polymer physics projects to enhance the molecular-level understandings on the structure-property-relationships of polymeric materials. Our research projects are interdisciplinary, addressing problems at the interface of organic, physical and polymer chemistry. Described below are selected examples of research topics in the group.

Polymer HPLC & Large Scale Purification of Block Copolymers

Two major goals of polymer HPLC are (1) the efficient separation and analysis of block copolymers and other chemically heterogeneous copolymers and (2) the development of a large scale separation method to obtain well-defined block copolymers in a gram scale. Temperature gradient interaction chromatography (TGIC) serves as a key method for the copolymer analysis via HPLC. For the large scale separation, we reported that well-defined block copolymers can be obtained based on either (i) selective adsorption of block copolymers or (ii) competetive adsorption of block copolymers over "polymeric impurities" using silica or modified-silica in solution.

The following block copolymers have been successfully purified in a large scale: PS-PMMA, PS-PI and PEO-PPO-PEO "Pluronic" block copolymers. Research Collaborators: Professor Taihyun Chang (POSTECH) and Professor Jan Genzer (NCSU)

Selected References:
S. Park, I. Park, T. Chang*, C. Y. Ryu* “Interaction-Controlled HPLC for block copolymer analysis and separation” J. Am. Chem. Soc.2004, 126 (29), 8906-8907
J. Han, B. H. Jeon, C. Y. Ryu*, J. J. Semler, Y. K. Jhon, J. Genzer* “Discriminating Among Co-monomer Sequence Distributions in Random Copolymers Using Interaction Chromatography”, Macromol. Rapid. Commun. 2009, 30, 1543-1548 (Cover article.)
C. Y. Ryu*, J. Han, W. S. Lyoo, “Block Copolymer Analysis and Purification” J. Polym Sci.: Polym. Phys. Ed. 2010, 48(24), 2561 – 2565. (Invited Viewpoint Article)
W. Powers, C. Y. Ryu*, Y. K. Jhon, L. A. Strickland, C. K. Hall, J. Genzer*, “Determining the Polydispersity in Chemical Composition and Monomer Sequence Distribution in Random Copolymers Prepared by Postpolymerization Modification of Homopolymers” ACS Macro Lett. 2012, 1, 1128-1133.
H. J. Park and C. Y. Ryu*, “Scalable PEO-PPO-PEO Triblock Copolymer Purification From Pluronics Through Competitive Adsorption” Polymer 2012, 53, 5052-5059.

Sustainable Polymers - Epoxy Thermosets from Vegetable Oils

One of the major challenges in macromolecular chemistry of this century will be to develop practical and scalable approaches to the replacement of petroleum-derived monomers and polymers with sustainable offset materials from biomass. Vegetable oils, triglyceride esters, can be chemically converted to epoxy thermoset monomers by oxidizing the unsaturated double bonds into epoxy groups. We have prepared epoxidized vegetable oils (EVOs) by a "green" oxidation method using H2O2 and W-based interfacial catalyst to introduce epoxy groups to vegetable oils, and used these EVO monomers for preparing epoxy thermosets via the photo and thermal cationic polymerization. (Research Collaborator: Prof. James Crivello)

These EVO epoxy thermosets provide an ideal materials platform to study the structure-property-relationships of networked polymers. These materials offer the following advantages of an ideal thermoset material to study the network formation with respect to monomer functionality (f). Rheological studies on the epoxidized vegetable oil thermosets served as an effect method to measure the molecular weights between crosslinks (Mx) in the epoxy thermosets and to ultimately elucidate the role of functionality of epoxy groups in EVO on the mechanical and thermo-physical properties of the epoxy thermoset materials.

Selected References:
H. J. Park, C. Y. Ryu, J. V. Crivello,"Photoinitiated Cationic Polymerization of Limonene 1,2-Oxide and alpha-Pinene Oxide" J. Polym Sci.: Polym. Chem. Ed. 2013, 51,109-117.
C. Y. Ryu, M. J. Spencer, J. V. Crivello, "Involvement of Supramolecular Complexes in the Capture and Release of Protonic Acids During the Cationic Ring-Opening Polymerization of Epoxides" Macromolecules 2012, 45, 2233-2241.

Outreach Program: Plastics are all around us & Research in Polymers

Plastic recycling is a significant society concern and the difficulty of implementing the plastic recycling in reusing plastic materials arises from the scientific fact that different plastics do not mix. Therefore, our research group is motivated to promote an eduational outreach program with a goal to provide K-12 students with the hands-on research opportunities to (1) characterize and identify plastic materials using cutting-edge thermal analysis instrument (specifically differential scanning calorimetry (DSC)) in polymer center at RPI, (2) promote their understanding on the thermal properties of polymers, such as glass transition and melting temperatures, which will be the main consideration to dictate the usage of polymers in modern life and (3) ultimately enhance their awareness of plastic recycling issues. Because different types of plastics do not mix, they have to be separated for the recycling and reuse of the plastic materials.

Results from K-16 students:
In partnership with summer@Rennselaer office at RPI, we are currently developing this program. Plastic sample analysis results will be summarized on this website to acknowledge their excellent contributions in the program. The following format will be used to organize their results, which will be posted on this website (click here .)

Student's Name, Affiliated School (City, State), Picture of sample, DSC result, Conclusion on which polymer materials are being used.

(c) Chang. Y. Ryu 2014