Ralph Colby

Ralph Colby

(814) 863-3457
Office Address: 
305 Steidle
Professor of Materials Science and Engineering
and Chemical Engineering
Department of Materials Science and Engineering

Google Scholar link

Research Interests: 
  • Proteins
  • Polyelectrolytes
  • Ionomers
  • Liquid crystalline polymers
  • Block copolymers
  • Miscible polymer blends
  • Branched polymers
  • Networks
  • Glass-forming liquids
  • Surfactants and colloidal suspensions
Ph.D. in Chemical Engineering, Northwestern University
M.S. in Chemical Engineering, Northwestern University
B.S. in Materials Science and Engineering, Cornell University

Ralph H. Colby received his B.S. in Materials Science and Engineering from Cornell University in 1979. After working for two years at the General Electric Company in rheology research and process development, he attended graduate school at Northwestern University, where he received his M.S. and Ph.D. in Chemical Engineering in 1983 and 1985. Graduate research focused on rheology of linear polybutadiene melts and solutions, and included 15 months as a visiting scholar in the Exxon Research and Engineering Company, Corporate Research - Science Laboratories. He then worked for ten years at the Eastman Kodak Company in their Corporate Research Laboratories. Rheology research areas over these ten years included linear polymer melts and solutions, miscible polymer blends, block copolymers, randomly branched polymers, polymer gels, liquid crystalline polymers, polyelectrolytes, proteins, surfactants and colloidal suspensions. In 1995, Dr. Colby was hired as Associate Professor of Materials Science and Engineering at the Pennsylvania State University and was promoted to Professor in 2000. He teaches an undergraduate course on Polymer  Processing and a graduate course on Polymer Physics. Dr. Colby has over 130 publications and published a textbook Polymer Physics in 2003.

Research Projects: 

Professor Colby’s research group is interested in a molecular-level understanding of dynamics in interesting liquids. Polymer liquids are good examples because they are viscoelastic: While polymer liquids do flow, they have considerable elastic character. Other examples include many “complex fluids” such as liquid crystals and surfactants. The Colby group measures the dynamics of these liquids using mechanical rheology and dielectric spectroscopy and also characterizes the liquid structure using neutron and x-ray scattering and optical methods. This is classical materials science research on structure-property relations but at the same time is highly innovative because it is applied to the liquid state. 

Technology Impacted By Research: 

Polymer dynamics, characterized by rheology, plays a vital role in solution and melt processing of polymers. Ion-containing polymers are a poorly understood class of materials that are potentially very important for actuators, sensors, separators between the electrodes of advanced batteries and fuel cell membranes.

One nice example is the study of ion transport in ionomer membranes. Ionomers are polymers with one type of ion covalently bonded to the chain and are ‘single-ion conductors’ in that only the unattached counterions can move rapidly in response to an applied electric field. Designing ionomers for facile ion transport is challenging and the Colby group is attacking this problem with ab initio calculations of ion interactions that guides our synthesis of new ionomers.

We use small-angle X-ray scattering, mechanical rheology and dielectric spectroscopy to understand what the ions are doing in these new ionomers. We quantify the temperature dependences of the fraction of ions in ion pairs, conducting triple ions and quadrupoles, for different ionomers with various counterions. There are a great many interesting liquids known in the world today and more are being discovered every day.

The Colby group’s mission is to understand in detail the structure-property relations of all interesting liquids. This is a great challenge and as such, only the best highly motivated students are able to participate in this exciting mission.


Editor, Journal of Rheology

Bingham Medal, Society of Rheology (2012)