Election to the National Academy of Engineering is among the highest professional distinctions accorded to an engineer. Academy membership honors those who have made outstanding contributions to "engineering research, practice or education, including, where appropriate, significant contributions to the engineering literature."
Robert E. Cohen is the St. Laurent Professor, co-director of the DuPont-MIT Alliance, and chair of the PhD CEP Steering Committee in the Department of Chemical Engineering. He was honored for his research on polymer morphology and surfaces, commercial products and processes, successful entrepreneurship and novel educational programs.
November 17, 2008 C&E News
Polymer patches add cargo to cells without disturbing normal activities
Cells can now accessorize with the latest in multilayered polymer patches without fear of cramping their style. The patches attach to immune cell surfaces like backpacks on schoolchildren, and they don't interfere with regular cell functions (Nano Lett., 8, 4446). The nanobackpacks could one day turn cells into drug delivery vehicles.
Several teams have tried to give cells new functions, including drug delivery, by encasing them in polymer shells that can be derivatized. But polymer encasement isn't universally applicable because "many cells need to interact with their surroundings to do their jobs," says MIT materials scientist Michael F. Rubner. Rubner teamed up with MIT engineers Darrell J. Irvine and Robert E. Cohen to figure out how to functionalize immune cells, which need their surfaces to communicate properly.
November 14, 2008 Technology Review
New designs for materials that repell all liquids
Materials under development at MIT could lead to coatings that repel both water and oil. A group of MIT researchers have created an improved set of design rules for making any surface impervious to any liquid, be it water or gasoline. Such materials could eventually have promise as fingerprint-repelling coatings, fuel filters, self-washing car paints, and stain-resistant clothing.
Last year, the MIT group, led by chemical engineer Robert Cohen and mechanical engineer Gareth McKinley, created the first superoleophobic, or oil-repellant, surfaces. They started with a polymer developed by the Air Force that contains large numbers of oil-repelling fluorine groups. The MIT researchers made the material even more oil resistant by using lithography to pattern it with overhanging microstructures. These tiny structures create air pockets that help suspend liquids and prevent them from penetrating to the surface. The MIT researchers found that the surfaces are both superoleophobic and also superhydrophobic, or water repelling. Because they repel everything, they're called omniphobic. [full article]
August, 2008 Scientific American
In 2003 Rubner and Cohen's laboratory at M.I.T. discovered how a minor change in construction could determine whether a superhydrophobic or superhydrophilic surface was produced. During a visit to China that year, Rubner recalls, he "got excited about some superhydrophobic structures" that were mentioned at a meeting. On his return, he directed some of his group's members to attempt to make such structures. His lab had developed a layer-by-layer technique for making thin films out of a class of compounds called polyelectrolytes. Ordinary electrolytes are substances that when dissolved in water split up into positively and negatively charged ions; common salt or sulfuric acid would be examples. Polyelectrolytes are organic polymers, plastic materials that, unlike most polymers, carry charge, either positive or negative. Rubner and Cohen stacked up alternating layers of positively charged poly(allylamine hydrochloride) and negatively charged silica particles. (In earlier work they had used coatings with silica particles to mimic the lotus's rough hydrophobic surface.)
To these multilayers, they added a final coating of silicone (a hydrophobic material), but along the way they noticed something intriguing: before they applied the silicone, the layer cake was actually superhydrophilic. In Rubner and Cohen's experiments, the silica layers had created a vast warren of nanopores, forming a sponge that soaked up any surface water instantly, a phenomenon called nanowicking. The silica-polymer multilayers they developed will not fog even if held over steaming water. If the pores get saturated, water starts running off the edge. When the wet conditions abate, the water in the nanowicks slowly evaporates away. [full article]
August, 2008 MRS Bulletin
A review article, published in the August 2008 issue of the MRS Bulletin, covered a number of interesting aspects of the Cohen-McKinley and Cohen-Rubner collaborations on wetting/nonwetting phenomena. [paper]
April, 2008 National Geographic
Though impressed by biological structures, Cohen and Rubner consider nature merely a starting point for innovation. "You don't have to reproduce a lizard skin to make a water collection device, or a moth eye to make an antireflective coating," Cohen says. "The natural structure provides a clue to what is useful in a mechanism. But maybe you can do it better." Lessons from the thorny devil may enhance the water-collection technology they have developed based on the microstructure of the Namib beetle, which they're working to make into water-harvesting materials, graffiti-proof paints, and self-decontaminating surfaces for kitchens and hospitals. Or the work may take them in entirely new directions. Ultimately they consider a biomimetics project a success only if it has the potential to make a useful tool for people. "Looking at pretty structures in nature is not sufficient," says Cohen. "What I want to know is, Can we actually transform these structures into an embodiment with true utility in the real world?" [full article]
December 6, 2007 MIT News
MIT engineers have designed a class of material structures that can repel oils, a novel discovery that could have applications in aviation, space travel and hazardous waste cleanup. Such materials could be used to help protect parts of airplanes or rockets that are vulnerable to damage from being soaked in fuel, like rubber gaskets and o-rings.
"These are vulnerable points in many aerospace applications," said Robert Cohen, the St. Laurent Professor of Chemical Engineering and an author of a paper on the work that appeared in the Dec. 7 issue of Science. [paper]
"It would be nice if you could spill gasoline on a fabric or a gasket or other surface and find that instead of spreading, it just rolled off," Cohen said. Creating a strongly oil-repelling, or "oleophobic" material, has been challenging for scientists, and there are no natural examples of such a material. [full article]
This work was also featured in Chemistry World in an article entitled "Giving oil the slip."
April 11, 2007 MIT News
Robert E. Cohen, the St. Laurent Professor of Chemical Engineering and co-director of the DuPont-MIT Alliance, has been selected as the first recipient of the Capers and Marion McDonald Award for Excellence in Mentoring and Advising. Established by Capers (who earned a master's degree in engineering from MIT in 1976) and Marion McDonald, this award is presented to a faculty member in the School of Engineering, who, through tireless efforts to engage minds, elevate spirits and stimulate high quality work, has advanced the professional and personal development of students and colleagues.
June 14, 2006 MIT News
When fog rolls in, the Namib Desert beetle is ready with a moisture-collection system exquisitely adapted to its desert habitat. Inspired by this dime-sized beetle, MIT researchers have produced a new material that can capture and control tiny amounts of water.
The material combines a superhydrophobic (water-repelling) surface with superhydrophilic (water-attracting) bumps that trap water droplets and control water flow. The work was published in the online version of Nano Letters on Tuesday, May 2. [paper]
Potential applications for the new material include harvesting water, making a lab on a chip (for diagnostics and DNA screening) and creating microfluidic devices and cooling devices, according to lead researchers Robert Cohen, the St. Laurent Professor of Chemical Engineering, and Michael Rubner, the TDK Professor of Polymer Materials Science and Engineering. [full article]
May 8, 2006 New Scientist
The Namib desert beetle, which lives on the parched sands of southwest Africa, collects drinking water using its wings, which are waxed and covered with an array of raised unwaxed bumps. The bumps strongly attract water, while the waxy areas repel it. On the six mornings per month when fog blows in from the Atlantic, the Namib beetle faces the wind and droplets of water stick to the bumps on its back. This water builds up before rolling down the water-repelling channels on the beetle's back and into its mouth.
UK researchers first worked out how the Namib beetle collects water in 2001. Now researchers from the Massachusetts Institute of Technology (MIT) have found a way to copy the design and modify it. They can decorate a surface with any microscopic pattern of water-attracting and water-repelling areas, leading to various possible applications.
"We've been able to mimic that surface and also to take the idea of having a surface with extreme differences in wet-ability into new territory," chemical engineer Robert Cohen from MIT told New Scientist. [full article] [paper]
September 19, 2005 C&E News
Michael F. Rubner and Robert E. Cohen may have just robbed Hollywood horror filmmakers of one of their most beloved clichés--the threatening note furtively traced in the fog of a bathroom mirror. That's because the MIT professors, in the departments of materials science and of chemical engineering, respectively, have developed a new superhydrophilic polymer coating that permanently eliminates fog from bathroom mirrors as well as windshields, eyeglasses, and camera lenses.
Rubner and Cohen make their coating from alternating layers of silica nanoparticles that are about 10 nm across and polyallylamine hydrochloride. The charged nanoparticles make the coating superhydrophilic so that when water droplets accumulate on the coated surface, they do so with a small contact angle, effectively forming a thin sheet of water. This eliminates fogging, which occurs when tiny water droplets condense on glass and randomly scatter light. [full article] [paper]
This work was also featured by MIT News in an article entitled "MIT research could clear up foggy problem."
September 5, 2005 C&E News
DuPont-MIT partnership gives students a preview of real-world research and life after school
Celia M. Henry, C&EN Washington
Unlike many research deals between corporations and universities, the management of the DuPont-Massachusetts Institute of Technology Alliance (DMA) has made education an integral component of the program from its outset. The alliance funds a number of fellowships for incoming graduate students and provides opportunities for collaborative research.
"It's often assumed that when big money flows into a university, it is somehow not in the students' interest," says Robert E. Cohen, a chemical engineering professor at MIT and an associate director of DMA. "We've had some very positive impact on the graduate enterprise at MIT."
At first, program officials imagined that the educational activities would take the form of workshops, seminars, and short courses for DuPont executives, managers, and scientists, but officials quickly realized they just couldn't spend that much money on such activities.
"We realized that there was a much better use of those funds," Cohen says. Although the programs for DuPont employees continue, most of the education money is now allocated for fellowships for incoming graduate students. At first called DuPont Fellows, these students are now known as DuPont Presidential Fellows following integration into a larger MIT program.
"A goal at MIT has been to uncouple the first year of graduate experience from the need to get involved in a pay-for-service research enterprise," Cohen says. "Students can select a thesis adviser from a position of strength and interest rather than need." [full article]
Professor Cohen Named AIChE Fellow
Professor Cohen was elevated to the rank of Fellow in the American Institute of Chemical Engineers.
December 8, 2004
Professor Cohen was notified in November of election to Fellowship in the American Physical Society for "seminal contributions to the understanding of the morphology and properties of heterogeneous polymers, in particular, pioneering fundamental work on molecular structure of block copolymers, and toughening of crystalline polymers."
June 7, 2004 C&E News
A surface of micrometer-sized hills and valleys dotted with waxy nanoparticles gives the lotus leaf its superhydrophobic self-cleaning properties. Water droplets bead up and roll off the rough surface, taking dirt and debris with them. Using a simple, water-based process, researchers from MIT have created a polyelectrolyte multilayer coating that mimics the leaf's tidy topography [Nano Lett., 4, 1349], published online May 18. The group, led by Robert E. Cohen and Michael F. Rubner, first creates micrometer-sized pores in a polyelectrolyte surface via multiple low-pH treatments. They then add nanoscale texture by depositing silica nanoparticles onto the material, followed by a semifluorinated silane coating. The material retains its superhydrophobic character even after being immersed in water for a week. By eliminating the semifluorinated silane coating step, the team can make the material superhydrophilic.
May 6, 2002 C&E News
Thin-film properties can be finely tuned through layer-by-layer assembly
Michael Freemantle, C&EN London
Rubner's group has shown, for example, that polyelectrolyte multilayered films of poly(acrylic acid) and poly(allylamine hydrochloride) can be employed as nanoreactors for preparing silver nanoparticle composites [Langmuir, 18, 3370 (2002)]. The work was carried out in collaboration with MIT chemical engineering professor Robert E. Cohen. The team also demonstrated that the size of the nanoparticles and the overall metal concentration within the films can be systematically controlled by the polyelectrolyte solution pHs and other processing conditions. "One implication of the control over the silver content in the multilayers is the ability to systematically change the optical properties of these nanocomposite films," the authors suggested. [full article]
November 14, 2000
The 2000 Charles M. A. Stine Award in Materials Engineering and Sciences (American Institute of Chemical Engineers) presented to Robert E. Cohen, Ph.D.
"For pioneering research contributions to polymer science and engineering, leadership in groundbreaking educational initiatives, and development of new products and processes."
June 5, 2000, C&E News
R&D alliance with MIT will help DuPont find its bearings in the field of biologically enhanced materials
Sophie Wilkinson, C&EN Washington
No one likes to admit they need help finding their way. Sometimes, though, the route is so complex and the destination so desirable that a little humility is a small price to pay for road map. In this spirit, DuPont recently established an alliance with the Massachusetts Institute of Technology that will help the company lay out a path toward its long-term materials and biotechnology goals. MIT and DuPont announced the five-year, $35 million research and development alliance last year (C&EN, Sept. 20, 1999, page 14).
Those in charge of the partnership made the application process as inclusive as possible in order to attract unconventional suggestions, says Robert E. Cohen, professor of chemical engineering at MIT. Cohen serves as codirector of MIT's activities in the alliance along with Douglas A. Lauffenburger, professor of chemical engineering and bioengineering.
For this very reason, all MIT faculty were invited to submit proposals for consideration. The application process was low-key, with proposals just two or three pages in length. "We wanted to make the initial approach very low-barrier," Cohen explains. This apparently worked, because applications--many incorporating DuPont input--were submitted by faculty in such departments as the Sloan School of Management, nuclear engineering, urban planning, biology, chemistry, and materials science.
"There is going to be a fluidity to this program," Cohen says. "People will come in and move out of teams as the trajectory of the program and focus of the teams change. What we launch on day one will not be what elutes from the stream at the end of five years." [full article]