CAMP December Newsletter: Page 1
Modeling of Gradient Copolymers with Materials Studio
Brendan Hofler, a graduate student in the Department of Chemical & Biomolecular Engineering, is using Materials Studio to model gradient copolymers that could be used to create surfaces that are anti-fouling and anti-bacterial. He is being advised by Professors Sitaraman Krishnan and John McLaughlin. At present Hofler is considering polymers that are uncharged.
Figure 1. A lamellar microstructure is seen in a gradient copolymer of styrene and pyridine mers.
Eventually, bactericidal cationic groups will be incorporated into the chains and free anions will be added to ensure overall electrical neutrality. Anti-fouling surfaces of polymers such as poly(ethylene glycol) are nonionic. To create an antibacterial surface, however, one needs to place cationic groups on the surface. The putative mechanism of antibacterial activity is that the positively charged groups on the surface interact with the negatively charged phospholipid molecules in the bacterium’s cell membrane and disrupt the membrane. Continued on page 3
Professor Dipankar Roy’s research group at CAMP is combining an array of leading-edge electro-analytical techniques to study the properties and the processing conditions of various functional materials for different types of advanced batteries. See Figure 2. The group’s ongoing efforts in the area of lithium ion batteries are now focused on studying the transport characteristics of lithium ions within the so-called solid electrolyte interphase (SEI) layers, typically formed during initial cycling, on rapid-charge/discharge cathodes. The Clarkson group forms these SEI layers in a current- or voltage-regulated mode on strategically designed cathodes that are based on mechano-chemically processed nanoparticles of lithium manganese oxide, lithium cobalt oxide or lithium iron phosphate. The cathode in a secondary lithium cell plays a major role in dictating the battery-function, and the Clarkson team has demonstrated how the SEI dictates the cathode’s charge/discharge performance. Continued on page 3
Distinguished University Professor S.V. Babu Is Co-Inventor of a New Patent
Clarkson’s Distinguished University Professor and CAMP Director S.V. Babu received his 28th patent. The US Patent 8,366,959, issued in February 2013, is titled “Abrasive compositions for chemical mechanical polishing and methods for using same.” The co-inventors are Suryadevara Babu, Professor Babu’s former Ph.D. students Pradeepa Dandu ( now at Intel) and Vamsi K. Devarapalli (now at IBM), and Guillaume Criniere and Claire Pitosis (both of Rhodia). It relates to slurry compositions and methods for use in the processing of silicon dioxide and silicon nitride films by CMP (chemical-mechanical polishing). This invention provides a stabilized composition for use in CMP processes with high reverse selectivity. Typically, it is desired that the selectivity, i.e., the ratio of the rate of removal of silicon dioxide to the rate of removal of silicon nitride is high. However, there are certain important and emerging applications where the reverse is desirable but is quite difficult to achieve. This patent, developed jointly with Rhodia, is for novel compositions that achieve the reverse selectivity.