The Cohen Group

Mission

What's New...

Many Cohen group members will be delivering talks and posters at the 2009 MRS Fall Meeting in Boston. Below is a list of the presenters:

The annual MIT-Princeton Microsymposium on Polymers was held this year in Princeton on June 10 and 11. As usual students and postdocs from the Cohen group at MIT and the Register group at Princeton presented updates on their research projects. The Cohengroup contributions are listed below:

Professor Cohen has been active in presenting invited seminars at various universities in this Spring 2009 semester. In February he travelled to Chemical Engineering Departments at Columbia University and at the University of Florida, in March he presented a lecture to the ACS Polymer Discussion Group at North Carolina State University, and in April he visited his graduate school alma mater, Caltech, for a seminar in Chemical Engineering. Also in April he presented a two-lecture sequence at the University of Pittsburgh, Department of Chemical Engineering, where he was the Bayer Distinguished Lecturer for 2009. The abstracts for the two Bayer lectures are shown below:

Bumpy Beetles, Moth Eyes, Butterfly Wings and Patchy Immune Cells: Exploitation of Layer-by-Layer Assembly in Bio-Inspired Materials Engineering

Tiny Backpacks for Cells

Collaboration with colleague Professor Michael F. Rubner of the Department of Materials Science and Engineering has led to a focus on novel and useful surface/thin-film phenomena that are observed in nature. We have employed a simple and elegant water-based assembly technique to provide conformal multifunctional coatings on a wide variety of substrates. Proper selection of nanoparticles and macromolecules, along with precise control of processing conditions, has enabled us to develop materials that mimic some fascinating natural phenomena: fog harvesting by desert beetles, broadband antireflection of the moth eye, and the brilliant structural colors found in hummingbird and butterfly wings. In a recent project we have assembled payload-containing 'backpack' structures on living immune cells for possible use in in-vivo imaging, therapies and bottom-up tissue engineering.

Designing Robust Omniphobic Surfaces

Omniphobic Surfaces

Superhydrophobic surfaces that display water contact angles greater than 150° with low contact angle hysteresis are becoming commonplace in the materials community. Microscopic pockets of air trapped beneath the high surface tension (glv = 72mN/m) water droplets lead to a composite solid-liquid-air interface in thermodynamic equilibrium. Previous experimental and theoretical work suggests that it should not be possible to form similar fully-equilibrated composite interfaces with drops of low surface tension liquids such as alcohols or alkanes (e.g. pentane: glv = 16 mN/m). In this lecture I will discuss novel surfaces that possess the required re-entrant topographical texture and surface chemistry to support strongly metastable composite solid-liquid-air interfaces for any liquid. Quantitative design parameters will be introduced to guide the development of these novel omniphobic surfaces. Examples that have been realized to date will be demonstrated: these embodiments include lithographically fabricated microhoodoos in silicon, randomly deposited electrospun fiber mats and dip-coated textiles.

PhDCEP student Zekeriyya Gemici (below, third from left, jointly supervised with Michael Rubner, DMSE) has been named one of this year's Graduate Student Gold Medal Awardees at the Materials Research Society (MRS) meeting. To achieve this status, Zek had to apply earlier in the fall and be selected to participate in an oral-presentation final competition that took place on Tuesday December 2 at the Hynes Auditorium, site of the MRS meeting.

Zek joins good company. Another Cohen/Rubner ChemE PhD student, Daeyeon Lee, won this prestigious award 2 years ago. Daeyeon recently finished a postdoc at Harvard and has moved to Philadelphia where he is now an assistant professor in the Chemical Engineering Department at the University of Pennsylvania.

The Cohen Group

The Cohen/Rubner collaboration has received attention recently in the popular science press as a result of the publication of a paper in Nano Letters (Nano Letters, Published ASAP online November 2008). Teaming with Professor Darrell Irvine of the MIT Department of Materials Science and Engineering allowed Cohen and Rubner to execute their work in which tiny polymer multilayer 'backpacks' carrying various 'payloads' were attached to living cells. An example of the press coverage is given in the following article that appeared in C&E News vol 86, no 46, p 10, November 17, 2008: "Tiny Backpacks For Cells".

The Cohen/McKinley collaboration has received attention recently in the popular science press following the publication of a paper in the Proceedings of the National Academy of Sciences (PNAS, November 25, 2008, vol. 105 no. 47 pages 18200 – 18205). An example is given in the following article that appeared recently in Technology Review: Making Materials Untouchable.

The work of the Cohen-Rubner collaboration was featured in the August 2008 issue of Scientific American. The article, "Self-Cleaning Materials: Lotus Leaf-Inspired Nanotechnology," discusses a range of topics from the creation of structure-induced hydophobilicity and hydrophilicity to the extention of the technology to address outstanding problems in both the consumer and scientific arenas.

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. The citation for the article is "Parameters for Superhydrophobicity and Superhydrophilicity," Anish Tuteja et al., MRS Bulletin 33, 752 (2008).

The 16th annual MIT-Princeton Microsymposium on Polymers was held at MIT on June 10-11, 2008. Please click here to view the schedule of events.

Professor Cohen and his work on biomimetic surfaces was featured in the April 2008 issue of National Geographic. The article, "Biomimetics: Design by Nature," can be viewed on the National Geographic site.

In an article published in Science on December 7, Professor Cohen, post-doc Anish Tuteja, and their collaborators at MIT and the Air Force Research Lab describe their exciting work on the design of superoleophobic surfaces. In the article, the group describes the design parameters for obtaining an superoleophobic surface and demonstrates such a surface showing extremely high contact angles (163° adv./145° rec.) with octane. You can more about this research and see videos of these amazing surfaces in action in the related press release.

This work has already generated strong interest in the popular science press as well, including being covered by Chemistry World in "Giving Oil the Slip."

The citation for the article is
"Designing Superoleophobic Surfaces," Anish Tuteja et al., Science 318, 1618 (2007).

A number of Cohen Group members and collaborators presented their research at the recent National ACS Meeting in Boston:

Professor Cohen has been selected as the first recipient of the Capers (1976) and Marion McDonald Award for Excellence in Mentoring and Advising. Established by Capers 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.

A recent publication from the Rubner and Cohen Groups has been generating a lot of interest in the popular press. The research, which focused on controlling the wettability of certain surfaces, was inspired by the biological design of the Namib beetle. More can be read about this research here.

The 14th Annual Princeton-MIT Microsymposium was held at MIT from 31 May - 1 June. The schedule of speakers can be viewed here.

During the Spring term of 2006, Professor Cohen was on leave at Balliol College, Oxford University. He was hosted by Dr. Paul Buckley in the Department of Engineering Science, the site of Professor Cohen's period of postdoctoral study in 1972-73. The sabbatical leave was sponsored in part by the following program:

MIT-Balliol College Exchange Program: Administered by the office of the Dean of Humanities, Arts, and Social Sciences at MIT, this program began in 1986 following a commitment made by William A. Coolidge to fund an exchange program for faculty at MIT and Balliol College at Oxford. The program provides for extended visits at each university. The financial administrator in the Dean's Office coordinates logistics and financial arrangements. All regular members of the MIT faculty are eligible to participate.

The Dupont-MIT Alliance (DMA) was highlighted in C&E news. The article can be viewed here.

C&E News highlighted research being conducted jointly by the Cohen and Rubner (DMSE) research groups at MIT on anti-fog coatings. The article can be viewed here.

Professor Cohen was elected to the rank of "Fellow" in AIChE.

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."