CPIMA / TECHNICHAL UNIVERSITY. MUNICH, GERMANY

The aim of Dr. Motomu Tanaka's stay in Prof. Alice Gast's laboratory (2-12 March, 2000) was to carry out the fundamental characterization of poly(2-(dimethylamino)ethyl methacrylate-block-methyl methacrylate) copolymers (PDMAEMA-b-MMA) at air-water interfaces. The primary goals of this project are to investigate the conformational changes due to the charging and decharging of the hydrophilic DMAEMA moieties, which slow the degree of ionization of 0.13 at pH = 8.5 and 0.61 at pH = 6.5, respectively.

Due to the restriction of time, Dr. Tanaka concentrated on the diblock with the DMAEMA molar concentration ratio of 50% (Mn = 9300). This diblock was dissolved easily into chloroform due to the lipophilic contribution from MMA groups. The Langmuir isotherm of the monolayer at the air-water interface was taken at pH = 6.5, 7.5, and 8.5. When the pH condition was titrated from pH = 7.5 to 6.5 at constant film area, a clear decrease in the surface pressure was observed. The interfacial properties of this molecule will be continuously studied in Munich.

At the second phase of this project, we plan to transfer the monolayer onto solid supports. Surface properties and conformational changes can be quantitatively studied by static/dynamic contact angle measurements (Stanford), specular X-ray reflectivity (Stanford), ellipsometry under controlled humidity (TU Munich) and impedance microscopy (TU Munich).

Motomu Tanaka, Ph.D.
Motomu_Tanaka@Physik.TU-Muenchen.DE
Research Assistant, Biophysics Institute
Tech. Univ. Munich, Germany