Nanotech 2010

Self Assembled Block-copolymer Nanocomposite Multilayer Thin Films for Reversible Temperature Triggered Responses

W.S. Tan, R.E. Cohen, M.F. Rubner, S.A. Sukhishvili
Massachusetts Institute of Technology, US

Keywords: amphiphilic triblock copolymer, layer by layer, thin films, temperature responsive


Thermo-mechanically responsive surfaces in aqueous environments are sought after for a variety of biological and micro-fluidic applications. Electrostatic self assembly of an A-B-A triblock co-polymer with a suitable polyanion was used to create smart surface coatings with up to 500% fully reversible, temperature dependent swelling from all aqueous processing. The dry thickness of the films can be easily controlled between 50nm-1um. Poly(2-(dimethylamino)ethyl methacrylate)-b-polypropylene oxide-b- poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA-PPO-PDMAEMA) was used as a dual pH and temperature responsive component and to create hydrophobic nano-domains within an electrostatically bound matrix. Incorporation of stimuli responsive block copolymers into electrostatically assembled thin films requires special attention to be paid to the molecular configuration of the stimuli responsive block. Our work investigates the block copolymer solution configuration and correlates how different aggregation states affect the temperature response of thin films assembled from these polymers. Detailed studies have uncovered key factors necessary to achieve high fidelity large extent yet fully reversible temperature induced volume transitions of multilayer thin films. The temperature dependent swelling of such thin films is applied to control membrane permeability. Further, such coatings can also be used for cell sheet engineering as well as selective small molecule binding and release.
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