AVS 58th Annual International Symposium and Exhibition
    Biomaterial Interfaces Division Thursday Sessions
       Session BI-ThP

Paper BI-ThP1
Physicochemical Characterization of Loop Polymer Brushes Prepared by Immobilization of End-Functionalized Poly(dimethylsiloxane)

Thursday, November 3, 2011, 6:00 pm, Room East Exhibit Hall

Session: Biomaterial Interfaces Poster Session
Presenter: Shinichiro Sakurai, Jst, Erato, Japan
Authors: S. Sakurai, Jst, Erato, Japan
H. Watanabe, Jst, Erato, Japan
A. Takahara, Kyushu University, Japan
Correspondent: Click to Email
A loop polymer brush is surface-tethered polymer chain of which both ends were anchored on the substrate surface to form a loop at a molecular level. The dynamics and physicochemical characterization of the loop brush has been a hot topic of several theoretical and experimental studies for polymer physics because the formation and interaction of loop brushes are key processes in many important biological and engineering processes. In this study, we synthesized loop polymer brushes by using end-functionalized poly(dimethylsiloxane) (PDMS) with various molecular weights as follows. A commercially available amino-terminated PDMS was fractionated by size exclusion chromatography (SEC) in the molecular weight from Mn = 7,000 to 100,000 with narrow molecular weight distributions (Mw/Mn~1.2), and transformed to a triethoxysilane (TES) end-functionalized PDMS on both ends. The silicon wafer was immersed in dichloromethane solution of the telechelic TES-terminated PDMS at 293 K for 24 h to immobilize both chain ends of the PDMS. The surface morphology of the telechelic PDMS-immobilized silicon wafer was observed by atomic force microscopy (AFM) under air at room temperature. The root mean square (rms) of the surface roughness was 0.6 nm in a 2 x 2 μm2 scanning area. The smooth morphology indicated that loop structure was formed without cross-linking and gelation of TES. Mono-functionalized PDMS was also synthesized to fabricate a linear brush on the silicon wafer. The thickness of these brushes in a dried state determined by ellipsometry increased from 2 to 5 nm with an increase in the molecular weight of Mn = 5,000 to 100,000. The loop and linear polymer brushes with same molecular weight showed the almost same thickness in a dried state. Apparent difference derived from a topology effect was not observed in a dried state. AFM measurement of the swollen thickness of the loop and linear brushes in a solution is in progress.