The synthesis and the characterization of a poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-blockpoly(2-methyloxazoline) (PMOXA-PDMS-PMOXA) triblock copolymer carrying polymerizable groups at both chain ends are described. This copolymer forms vesicular structures in dilute aqueous solution, the size of which can be controlled in the range from 50 nm up to about 500 nm. The methacrylate end groups of the triblock copolymer can be polymerized in the vesicular aggregates using an UV-induced free radical polymerization. Static and dynamic light scattering, scanning electron microscopy, and transmission electron microscopy on both the resulting nanocapsules and their nonpolymerized precursors clearly show that the cross-linking polymerization does not lead to morphological changes in the underlying vesicles. Moreover, due to their cross-linked structure, the nanocapsules are shape persistent, thus maintaining their integrity even after their isolation from the aqueous solution.
A –CH2NMe2 group attached to ferrocene can be used as an ortho/ortho‐directing group to selectively synthesize 1,2,3‐substituted ferrocenes, which are used as starting materials for novel 1,3‐linked ferrocene polymers and oligomers. The Sonogashira coupling reaction of 1‐(I),2‐(CH2NMe2)‐ferrocene with HC≡CSiEt3 results in 1‐(C≡CSiEt3),2‐(CH2NMe2)‐ferrocene (1b), which – following an ortho‐lithiation/iodination sequence – is converted into 1‐(I),2‐(CH2NMe2),3‐(C≡CSiEt3)‐ferrocene (1d). Removal of the –SiEt3 protective group yields 1‐(I),2‐(CH2NMe2),3‐(C≡CH)‐ferrocene, which can be polymerized under Sonogashira conditions to yield a soluble, bimodal ferrocene‐acetylene polymer of MW = 3700/7100 and Mn = 4272. To understand the properties of the polymer better and to evaluate the effect of 1,3‐substitution on the electronic communication between the metal centers, a divergent‐convergent approach was used to synthesize defined di‐, tri‐ and tetranuclear ferrocenes. Accordingly, 1d was cross‐coupled with 1‐(CH2NMe2),2‐(C≡CH)‐ferrocene to give [2‐(CH2NMe2)‐ferrocene‐1‐yl]‐C≡C‐[2‐(CH2NMe2),3‐(C≡CSiEt3)‐ferrocene‐1‐yl] (2a). Removal of the protective group in 2a led to [2‐(CH2NMe2)‐ferrocene‐1‐yl]‐C≡C‐[2‐(CH2NMe2),3‐(C≡CH)‐ferrocene‐1‐yl] (2b), which was treated with [1‐(I),2‐(CH2NMe2)ferrocene‐3‐yl]‐C≡C‐[2‐(CH2NMe2),3‐(C≡CSiEt3)‐ferrocene‐1‐yl] (2c) to result in the corresponding tetrameric ferrocene (4a).
The mechanism of the strictly alternating anionic copolymerization of phenyl glycidyl ether (PGE) and phthalic anhydride (PA) was initiated by various imidazoles. Because of the strictly alternating copolymerization polyesters with a repeating unit of PGE-PA were obtained. The mechanism of the reaction was analyzed by means of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). With this technique the molar masses of the oligomers, the molar mass of the repeating unit, the weight-average molar mass M,,, and the number-average molar mass Mn, their ratio B,,,/Mn and the residual molar mass could be calculated. The strictly alternating copolymerization was easy to prove because the molar masses of PGE and PA are slightly different. The question whether the initiator remains chemically bound during the whole reaction could be solved. To this end polyesters obtained by initiation with various imidazoles with different molar masses were synthesized. The calculated residual molar masses correspond exactly to the molar masses of the imidazoles.
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