Chapter 23
Downloaded by UNIV OF CALIFORNIA SAN DIEGO on July 25, 2016 | http://pubs.acs.org Publication Date: March 23, 2006 | doi: 10.1021/bk-2006-0928.ch023
Poly(Ferrocenylsilane-block-methacrylate)s via Sequential Anionic and Atom Transfer Radical Polymerization *
*
Mark A.Hempenius ,Igor Korczagin, and G. Julius Vancso +
M E S A Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
The synthesis and characterization of PFS-b-PMMA block copolymers, obtained by a sequential polymerization approach, is described. The poly(ferrocenylsilane) (PFS) block was prepared by anionic polymerization of [1]dimethylsilaferrocenophane, and end-capped using 3-(tertbutyldimethylsiloxy)propyldimethylchlorosilane. Deprotection yielded a 3-hydroxypropyl-terminated PFS which was acylated with 2-bromoisobutyric anhydride. The 2-bromoisobutyryl end-functionalized PFS was used as a macroinitiator for controlled A T R P . Well-defined PFS-b-PMMA block copolymers with low polydispersities (M /M 97%) and triethylamine (>99.5%) were obtained from Fluka. Platinum cyclovinylmethylsiloxane complex in cyclic methylvinylsiloxanes (3-3.5% Pt) was obtained from A B C R , Karlsruhe. w-Heptane (for synthesis) and 4-(dimethylamino)pyridine (for synthesis) were purchased from Merck. Tetrahydrofuran (THF) for anionic polymerizations was distilled from sodium-benzophenone under argon, degassed in three freeze-pump-thaw cycles and distilled by vacuum condensation from nbutyllithium. Toluene for A T R P was degassed on a high-vacuum line and distilled by condensation. 2-Bromoisobutyric anhydride was prepared according to a literature procedure. H N M R (CDC1 ): δ 2.00 ( C H , s). The A T R P 24
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Schubert et al.; Metal-Containing and Metallosupramolecular Polymers and Materials ACS Symposium Series; American Chemical Society: Washington, DC, 2006.
323 catalyst, (p-cymene)ruthenium(II) chloride-tricyclohexylphosphine, was synthesized as described earlier. Techniques. *H N M R spectra were recorded in CDC1 on a Varian Unity Inova (300 M H z ) instrument at 300.3 M H z and on a Varian Unity 400 spectrometer at 399.9 M H z . A solvent chemical shift of δ = 7.26 ppm was used as a reference. G P C measurements were carried out in T H F at 25 °C, using microstyragel columns (bead size 10 mm) with pore sizes of 10 , 10 , 10 and 10 Â (Waters) and a dual detection system consisting of a differential refractometer (Waters model 410) and a differential viscometer (Viscotek model H502). Molar masses were determined relative to polystyrene standards. Monomer purification. [l]Dimethylsilaferrocenophane was prepared and purified as described earlier. Methacrylate monomers were degassed on a high-vacuum line in three freeze-pump-thaw cycles and distilled under vacuum from calcium hydride immediately before use. Anionic polymerization. [l]Dimethylsilaferrocenophane polymerizations were carried out in T H F in an MBraun Labmaster 130 glove box under an atmosphere of prepurified nitrogen (
