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  October 20, 2003

Weiss Brings World Of Polymers
To Life With Everyday Examples

Professor Bob Weiss often introduces his students to the world of polymers with a memorable clip from the 1967 movie, The Graduate.

Dustin Hoffman, playing a graduate fresh out of college, is pulled aside at a pool party by a middle-aged friend of the family.

Image: Robert Weiss and Sang-Yean Shim

Robert Weiss, Board of Trustees Distinguished Professor of Chemical Engineering, left, and Sang-Yean Shim, a visiting professor from South Korea, use a small angle x-ray scattering instrument for measuring polymer structure.

Photo by Melissa Arbo

"I just want to say one word to you," the man says.

"Yes, sir," replies Hoffman.

"Just one word. Plastics."

For Weiss, the script might only have been improved with the word "polymers." But never mind; plastics are synthetic polymers, and The Graduate serves Weiss well.

It also gives a glimpse into the kind of approach he takes to teaching a subject of monumental proportion and complexity.

While polymers and their relationship to human beings are serious business, Weiss likes to convey that they can also be fun.

"In class I like to show my students a pull chain from a light fixture and tell them each little ball represents an atom," he says. "To make a polymer, the chain would have to be 90 feet long, and that's just one molecule. Then we start talking about the interactions between molecules."

Weiss has plenty of other examples to illustrate his points. "One of the coolest experiments involves a rubber band," he says. "No other material on earth stretches like a rubber band and comes back to its original shape. That has to do with the long chain nature of the molecule. Or look at Silly Putty, another polymer. Is it a liquid or a solid? It bounces. Leave it alone and it flows into a puddle. What about window glass? It's actually a liquid flowing very slowly, as you can see from the old cathedrals of Europe, where the glass is thicker at the bottom."

Weiss, who holds 14 patents for his work in the field, has been teaching at UConn for 23 years. He was recently named a Board of Trustees Distinguished Professor, an honor that recognizes both his scholarship and his contributions to the University and its students.

In making the nomination, Joseph Helble, professor and head of chemical engineering, noted that Weiss has authored more than 150 scholarly articles, edits two major polymer journals, and attracts substantial outside funding for research.

In an interview Helble adds, "Bob is great at teaching the wonderful and unexpected things polymers bring us, as well as mentoring younger faculty and advocating for them. Bob also has a reputation for speaking his mind. I value his feedback and know I can always go to him for a quick gut reaction and sanity check."

Colleagues at such schools as Princeton, Dartmouth, and McGill were also enthusiastic in their support of the nomination:

"He displays a deep fundamental understanding of the science [and] a practical grasp of what is essential for achieving progress," said a British professor who worked with him while he was on sabbatical in England as a Fulbright Scholar.

"It's a nice feeling, knowing that my colleagues thought enough of me to put me up for this honor, and the University wanted me to have it," he says.

So what are polymers all about? A Google search turns up 1.46 million references, and no wonder, since polymers are present everywhere in ordinary life and in the human body itself.

The simplest definition of polymers is to call them long chain molecules that occur both naturally and synthetically. Natural polymers include such things as a turtle's shell, proteins and starches in foods, latex, and DNA. Synthetic examples include all of life's plastics and "polys" - polyethylene used in packing and insulation; polypropylene used in carpeting and automotive instrument panels; and polyvinyl chloride for vinyl siding, clear plastic bottles, shower curtains, and raincoats.

Weiss's research and teaching revolves around understanding the chains of molecules that create different polymers, and how to manipulate polymers into more useful products for mankind. His research often stretches beyond chemical engineering into such disciplines as physics, engineering, and the bio-sciences. He's been elected as a Fellow to three major - and very different - scientific societies: the American Physical Society, the Society of Plastics Engineers, and the North American Thermal Analysis Society. He has also received major international awards in education, research and engineering from the Society of Plastics Engineers.

The mainstay of his research for the past 25 years has been ionomers, polymers that contain bonded acid or salt groups. These materials exhibit unimaginably tiny areas, or "nanometer-sized domains," that significantly influence their physical and mechanical properties. A human hair is on the order of 1,000 nanometers in diameter, huge by comparison with the world Weiss works in.

Weiss has been especially interested in determining the relationship between the polymer structure and the properties of these materials, which have such diverse applications as the cover of golf balls and the proton exchange membrane in a fuel cell.

His work in this field occasionally requires him to tee up a number of golf balls and evaluate which ones behave best.

Other research projects have involved contact lenses and recycling, a perennial topic because of the tendency of polymer products to degrade very slowly.

"For the contact lens project, we're working with an industry partner to develop new hydrogels that could be injection molded into contact lenses," Weiss says. "Another bio-science project we have involves the development of plastic dental bridges that could be shaped entirely in a dentist's office, rather than being sent out."

Much of Weiss's research revolves around basic problems with mixing different polymers to develop new materials, such as blends of electrically conducting polymers and non-conducting polymers.

To illustrate the difficulty with blending most polymers, he uses the example of oil and water. The only way to mix them (as in a clean-up operation) is to introduce a third component that "likes" both. While at UConn, Weiss received a patent for just such a product, known as a "compatibilizer."

Although polymers are ordinarily insulators, Weiss says a new generation of "plastic electronics" is on the horizon. It has been learned that some polymers can transport electrons, opening up the possibility of flexible electronic displays or electronic paper. He is using these new materials to design and engineer chemical sensors using polymer foams similar to materials used as air filters.

Weiss grew up in Cleveland. His father was a NASA aeronautical engineer and his mother an elementary school teacher. He received his undergraduate degree from Northwestern and his Ph.D. from the University of Massachusetts. He worked briefly for Exxon before turning to academia.