Surface Graft Polymerization
| Graft polymerization typically
involves polymer grafting and/or graft polymerization as shown in the
Figure to the left. Engineering of ceramic-supported polymer surfaces,
consisting of with a terminally anchored polymer layer, requires careful
control of the surface density and molecular weight of the polymeric
chains. Our group developed a number of different methods of surface graft polymerization including a patented two-step method that is based on surface activation with organosilanes, a controlled free-surface graft polymerization and a plasma-assisted graft polymerization. |
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| The degree of polymer graft yield, as well as chain length and density, are sensitive functions of reaction conditions as shown in the Figure to the left. | |
| Our group has developed such models for free-radical polymerization (see Figure to the left for the PVP/silica system). These models enable predictions of graft yield and molecular weight distribution of the tethered polymer chains. |
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| To date, detailed kinetic models for the graft polymerization of vinylpyrrolidone and vinyl acetate (see Figure to the left) have been developed. The kinetic models account for the simultaneous homopolymerization and graft polymerization reactions and consider the unique initiation mechanisms of those systems. Present work is continuing to allow improved predictions of the molecular weight distribution of the terminally anchored polymer chains. Also, various surface modification procedures and reaction conditions are being investigated in order to provide for improved control over the molecular weight distribution of the surface. |
The resulting
physicochemical and transport properties of the grafted polymer layer
depend on the conformation and topology of the tethered polymer phase.
The polymer chain configuration will vary from the extreme brush like
configuration for high density coverage to separated chains in the
so-called mushroom regime as shown below.
Grafted Polymer Chains
Graft Polymerization Methods
In order to control the structure of the grafted polymer phase (both chain density and chain length) various graft polymerization methods have been proposed as summarized in the Table below.
References:
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Yoshida, W, Castro, R. P., Jou, J. D. and Cohen, Y., "Multilayer alkoxysilane silylation of oxide Surfaces," Langmuir, 17, 5882-5888 (2001).
- Nguyen, V., W. Yoshida, and Y. Cohen, "Graft Polymerization of Vinyl Acetate onto Silica", in press, J. Appl. Polym. Sci. (2002).
- Nguyen, V., W. Yoshida, J-D. Jou and Y. Cohen, "Kinetics of Free-Radical Graft Polymerization of 1-vinyl-2-pyrrolidone onto Silica," Journal of Polymer Science Part A: Polymer Chemistry, Volume 40, Number 1, 26-42 (2002).
- Cohen, Y., W. Yoshida, V. Nguyen, N. Bei and J-D Jou, "Surface Modification of Oxide Surfaces by Graft Polymerization," in "Oxide Surfaces", J. A. Wingrave (editor), Marcel Dekker, New York (2001).
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Chaimberg, M. and Yoram Cohen, "The Kinetics of Graft Polymerization onto Silica Substrates," AIChE Journal, 40, 294-311 (1994).
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Browne, Tom, M. Chaimberg and Yoram Cohen, "Graft Polymerization of Vinyl Acetate onto Silica," Journal of Applied Polymer Science, 44, 671-677 (1992).
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Chaimberg, M. and Yoram Cohen, "Free-Radical Graft Polymerization of Vinyl Pyrrolidone onto Silica," Industrial and Engineering Chemistry Research, 30, 2534-2542 (1991).
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Last update:
10/23/2004
