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CAMP June Newsletter: Page 2

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CAMP Professor Krishnan’s Research Involves Novel Functional Polymers

Figure 1. On the left, is a grazing incidence small angle X-ray scattering (GISAXS) map of a nanostructured thin film of a marine antifouling block copolymer. In the GISAXS technique, synchrotron X-rays are used to determine the shape, dimensions, and orientation of nanostructures within thin films. The image on the right is an atomic force microscopy (AFM) phase image of the same film that shows cylindrical domains of a block copolymer (microphase), with the axes of the cylinders aligned parallel to the substrate.

CAMP Professor Sitaraman Krishnan, of Clarkson University’s Department of Chemical & Biomolecular Engineering, is interested in the thin film and colloidal properties of novel functional polymers. His recent work involved the synthesizing of block copolymers for use as coatings to prevent marine biofouling. See Figure 1. Marine biofouling is a worldwide problem with severe economic and environmental penalties. The increase in fuel consumption, because of fouling-induced hydrodynamic drag on ships, is estimated to cost about $30 billion per year ( The added fossil fuel consumption leads to an emission of several million tons of greenhouse gases into the environment. Biofouling is also a major issue in desalination plants and for fish farms.

Professor Krishnan has synthesized and studied novel block copolymers that are highly effective in preventing marine bioadhesion when spray-coated onto surfaces. Block copolymers are macromolecules that consist of two or more segments of simple polymers joined together by chemical bonds. By suitably tailoring the chemical microstructure, block copolymers can be made to self-organize to form nanostructured assemblies. A recent paper coauthored by Dr. Krishnan discussed the molecular self-assembly and surface characteristics of these block copolymer thin films [J. Polym. Sci. Part A: Polym. Chem. 47, 267-284 (2009)]. Links to Dr. Krishnan’s publications and patents on anti-biofouling coatings can be found at the following website.

Dr. Krishnan and his students, Ms. Lin Wu and Ms. Lalitha Ganapatibhotla, are interested in the synthesis and application of a novel class of ionic fluorinated polymers that contain polar groups such as poly(ethylene glycol) (PEG) or pyrrolidone. The chemical structure, and the self-assembling characteristics, of these amphiphilic polymers, make them promising as functional materials for several advanced technological applications such as anti-biofouling coatings (for biomaterial surface modification) and polymer electrolytes (for dye-sensitized solar cells and lithium ion batteries). The objective of Ms. Wu’s graduate research is to develop novel gradient copolymers and graft copolymer architectures that are both protein repellant and bactericidal.

Titania-based dye-sensitized solar cells (DSSCs) are highly promising as cost-effective alternatives to crystalline silicon solar cells. Commercialization of DSSCs is, however, hindered by the need of liquid electrolytes which limit the long-term stability and high temperature operation of these devices. Ms. Ganapatibhotla’s research goal is to develop high-efficiency solid-state dye-sensitized solar cells using the same class of fluorinated polymers that are being developed in the antifouling research. These novel polymer electrolytes will act as suitable matrixes for efficient transport of redox mediators and facilitate regeneration of the dye.

A third area of ongoing research in the Krishnan group is the synthesis of stimulus-responsive polymer particles for controlled release of bioactive molecules. In a project funded by New World Pharmaceuticals, graduate student Mr. Venkat Vendra is designing temperature and pH-responsive microparticles for encapsulation of bioactive molecules, and their 'delayed release' into the gastrointestinal tract

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