390181 pH and Thermo-Responsive Behavior of Amino (Meth)Acrylate Polymer Brushes on Silicon Substrates By in-Situ Ellipsometry and Atomic Force Microscopy

Tuesday, November 18, 2014: 8:45 AM
International 10 (Marriott Marquis Atlanta)
Erick S. Vasquez1, Shijie Ding2 and Keisha B. Walters1, (1)Dave C. Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS, (2)College of Life Science and Chemical Engineering, Huaiyin Institute of Technology, Huaian, China

Stimuli responsive polymers have potential use in a wide range of applications, from nanometer-scale drug delivery to flow control in microfluidic devices.  In this study, surface-confined atom transfer radical polymerization (ATRP) and single electron transfer living radical polymerization (SET-LRP) were used to synthesize a series of surface-grafted poly(amino (meth)acrylate) brushes from silicon substrates that were pre-modified with silane self-assembled monolayers (SAMs).  Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), poly(2-(dimethylamino)ethyl acrylate) (PDMAEA), poly(2-(diethylamino)ethyl methacrylate) (PDEAEMA), and poly(2-(tert-butylamino)ethyl methacrylate) (PTBAEMA) were synthesized and characterized using in-situ techniques.  In-situ spectroscopic ellipsometry studies were performed using a temperature-controlled liquid flow cell to collect dynamic and equilibrium data under various pH/ionic strength conditions.  Multilayer models were generated based on a Gaussian general-oscillator (GenOsc) dispersion model that accounted for the polymer, initiator, and silane SAM layers.  In-situ atomic force microscopy (AFM) measurements were also collected under different pH and temperature conditions using a liquid cell. AFM was used to identify changes in the polymer brush structure, including phase separation/aggregation behavior changes. In addition to measuring thickness changes, response rates, and stimuli conditions for these surface-tethered pH and temperature responsive poly(amino (meth)acrylates) brushes, for the first time application of the GenOsc model to evaluate the optical constants of surface-tethered polymer brushes is presented.

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See more of this Session: Nanostructured Polymer Films
See more of this Group/Topical: Materials Engineering and Sciences Division