The objective of this project is to explore layer-by-layer self-assembly of temperature and pH-responsive block copolymer micelles with polyelectrolytes at surfaces. Future applications of such films include controlled delivery of active components from surfaces. A combined theoretical and experimental approach is being built through international collaboration between our group and groups of Dr. Kramarenko and Dr. Potemkin at Moscow State University in Russia. Publications: one paper submitted to Macromolecules, two conference proceedings papers accepted to Polymer Materials: Science and Engineering, and two manuscripts are in preparation.

Materials World Network: US-Russia Collaboration on Responsive Micelles at Surfaces -- A Combined Experimental and Theoretical Approach

Svetlana Sukhishvili, Stevens Institute of Technology, DMR 0710591

pH-triggered release of active compounds from micelles in solution (A) and from surface multilayer films (B).

pH 8

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Self-assembly of PDMAEMA50-b-PNIPAM50 in 0.3M Na2SO4

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Self-assembly of PDEA50-b-PNIPAM50 in low-salt solutions as a function of pH

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Self-assembly of PDEA50-b-PNIPAM50 micelles at surfaces

We have also synthesized poly-(2-diethylamino)ethylmethacrylate-b-poly-N-isopropylacrylamide (PDEA-b-PNIPAM) copolymers by ATRP technique. Self-assembly of such polymer in aqueous solutions at room temperature is induced by deprotonation of PDEA block at high pH values, resulting in formation of PDEA-core/PNIPAM-corona micelles (left). These responsive micelles were also deposited at surfaces (right). Theoretical treatment of these transition is being developed by Russian collaborators.

We have synthesized amphiphilic pH- and temperature reposnive poly[2(dimethylamino)ethyl methacrylate)-b-poly(N-isopropylacrylamide)] (PDMAEMA-b-PNIPAM) block copolymers, and found a new type of phase transitions and restructuring in pH-responsive polymeric micelles.

This is first experimental observation of the phase transition between small, strongly charged and big neutral polymer micelles. Practical consequences of such findings are significant, as such transitions present novel ways for controlled delivery of functional molecules.

Education and Outreach

Funding provided by the NSF supported two graduate students: Irem Erel Unal (4thyear), and Li Xu (1st year, partial support). In addition, a 1st year Ph. D. student Zhichen Zhu who was supported as a TA, has participated full time in project. Results of the project will be incorporated into graduate courses in the Department of Chemistry and Chemical Biology CH “Polymers at Solid-Liquid Interfaces” and CH/NANO 525 “Techniques of Surface and Nanostructure Characterization”

taught in fall 2008/spring 2009.

Left: US graduate student Irem Unal (second from right) and Russian graduate student Elena Nyrkova (center) participates in the discussion of recent results the US-Russia project at the symposium "Molecular Order and Mobility in Polymer

Systems“ in St. Petersburg, Russia on June 2, 2008. Right: A high school student Daja Mayner (front) supported by the NJ Liberty Science Center “Partners in science” Program, learns about the NSF-sponsored research in spring/summer of 2008.

NSF-supported project has been presented in seven presentations given by the PI and graduate students at the following meetings: ACS Annual Meeting, Philadelphia, PA, August 17-21, 2008 (three presentations); 40th Middle Atlantic Regional Meeting, New York, NY, May 17-21, 2008 (two presentations); and "Molecular Order and Mobility in Polymer Systems", St. Petersburg, Russia, June 1-6, 2008 (two presentations).

Materials World Network: US-Russia Collaboration on Responsive Micelles at Surfaces -- A Combined Experimental and Theoretical Approach Svetlana Sukhishvili, Stevens Institute of Technology, DMR 0710591

First steps in collaboration: PI Sukhishvili (US) and Kramarenko and Potemkin (Russia) discuss first results of the project in December of 2007.