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SURFACE MODIFICATION OF SILICATE SUBSTRATES

Wang, Ying
http://rave.ohiolink.edu/etdc/view?acc_num=akron1164641616

Abstract Details

2006, Doctor of Philosophy, University of Akron, Polymer Science.
Polymer chains tethered to a surface have been extensively studied in the area of surface modifications. Exploratory efforts on surface modification in this research have been focused on three areas: first, investigation of surface-grafted, Y-shaped, diblock copolymer thin films using a “grafting-to” method; second, a polymer brush grafted from a uniform initiator monolayer; and third, binary mixed homopolymer brush fabrication using a “grafting-from” technique. Y-shaped diblock copolymers grafted onto a flat surface were predicted to give rise to a rich variety of novel patterns. However, there have been few experimental reports primarily because these systems require challenging synthetic approaches. We used a synthetically simple approach to produce a Y-shaped AB diblock copolymer brush. A polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) block copolymer containing a methylhydridosilane linking group was chemically “grafted-to” an 8-trichlorosilyloctene monolayer via a 1-step hydrosilylation reaction. The resulting Y-shaped thin film exhibited a low grafting density, characteristic of the “grafting-to” technique. To further decrease the miscibility of the two arms, methyl iodide was reacted with the P2VP block to produce quaternary ammonium groups. The surfaces before and after quaternization exhibited surface compositional changes upon exposure to block-selective solvents. To create the optimal surface for a “grafting-from” polymerization, a uniform initiator layer on the silicate substrate is important. However, uniformity is a persistent issue when multifunctional silanes are used because of side-reactions and moisture sensitivity. In an attempt to minimize these problems, an allylsilane was synthesized to functionalize our substrates. Using atomic force microscopy, the allylsilane monolayer was found to be more uniform than the monolayer prepared from a trichlorosilane. Atom transfer radical polymerization was applied to graft polystyrene brushes from the initiator-bound surface. Mixed polymer brushes, consisting of diblock or triblock copolymer brushes, Y-shaped diblock copolymer brushes and mixed homopolymer brushes, have been extensively studied because of the potential for ampliflying the combined effects of conformational changes and microscopic phase separation. Macroscopic phase separation is generally suppressed by the tethering of one chain end to the surface. Both theoretical and experimental work have indicated that symmetric mixed homopolymer brushes would be able to undergo a solvent-induced transition between lateral and perpendicular microphase separation. Therefore, we devised a simple approach for one-pot, controlled brush synthesis by combining nitroxide-mediated radical polymerization and living cationic ring-opening polymerization. We observed that the mixed homopolymer brush showed surface changes when subjected to different solvents.
Roderic Quirk (Advisor)
147 p.
polymer brushes; surface modification; silicate substrates

Recommended Citations

Citations

  • Wang, Y. (2006). SURFACE MODIFICATION OF SILICATE SUBSTRATES [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1164641616

    APA Style (7th edition)

  • Wang, Ying. SURFACE MODIFICATION OF SILICATE SUBSTRATES. 2006. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1164641616.

    MLA Style (8th edition)

  • Wang, Ying. "SURFACE MODIFICATION OF SILICATE SUBSTRATES." Doctoral dissertation, University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1164641616

    Chicago Manual of Style (17th edition)

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© 2006, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.