Nitroxid-vermittelte Polymerisation mittels NMR-Sonden tragender Initiatoren zur Darstellung von coil-rod-coil-Blockcopolymeren

• Main Author: Tietz, Marco
• Format: Doctoral or Postdoctoral Thesis
• Language: German
• Published: Universität Bielefeld 2016
• Subjects: ddc:540; Carbonic acid
• Online Access: https://nbn-resolving.org/urn:nbn:de:hbz:361-29049958; https://pub.uni-bielefeld.de/record/2904995; https://pub.uni-bielefeld.de/download/2904995/2904996

Tietz M. Nitroxid-vermittelte Polymerisation mittels NMR-Sonden tragender Initiatoren zur Darstellung von coil-rod-coil-Blockcopolymeren . Bielefeld: Universität Bielefeld; 2016. A systematic synthesis for coil-rod-coil(c-r-c) block copolymers with differing material characteristics should lead to the usage of c-r-c block copolymers as surface probes and for the study of the self assembling behavior of c-r-c block copolymers. Therefor 2,2,5-Trimethyl-4-phenyl-3-azahexane-3-nitroxide (TIPNO) based alkoxyamines with covalently attached NMR probes where synthesized starting from nitroxides and functionalized styrenes. These alkoxyamines were used as initiators for the synthesis of copolymers of styrene with 3-(tert -butoxy)-3-oxopropyl-, chloromethyl-, hydroxymethyl- and 3-hydroxypropyl- substituted styrenes as well as vinylpyridine. Additionally to these copolymers the homopolymer poly(4-hydroxymethyl-styrene) was synthesized using nitroxide mediated polymerisation (NMP). For the buildup of the NMR-probe carrying alkoxyamines TIPNO, two TIPNO derivatives, one with an ethoxy and one with a trifluoro-methoxy, and methoxy substituted styrenes were used. In contrast to the GPC analysis, where a polymer standard as reference is necessary to determine the molecular weight of polymers the analysis of polymers via NMR spectroscopy does not need a calibration. The chemical shift of the methoxy protons is located at 3.5-4.0 ppm and the signal can be integrated separately from all other signals of the used alkoxyamines and the synthesized polymers. This allows to determine the degree of polymerization and the degree of co-polymerization, even when the structure of the (co)polymer differs from any purchasable standard. Additionally, TIPNO-based alkoxyamines with bromo and protected alkynyl substituents were synthesized. These functional groups allowing further modification. The bromo derivative was converted into the carbonic acid and the iodo derivative via halogen metal exchange followed by reaction with CO2 or I2. The alkoxyamines with halogen and the deprotected alkyne function were used for Sonogashira-Hagihara cross-couplings with oligo(p-phenyleneethynylene) (OPPE) rods to obtain rod-shaped NMP initiators. Additionaly, the alkyne group was used for copper catalyzed [2+3] cycloadditions with azides. With these alkoxyamines copolymers of styrene and styrene derivatives where synthesized to obtain r-c block copolymers with varying coil segments. Through further reactions of the r-c block copolymers c-rc block copolymers were synthesized. It was known that the conversion of a copper catalyzed oxidative dimerisation of two r-c block copolymers originated from a TIPS protected r-c block copolymer is not quantitative. The key step of synthesizing c-r-c block copolymers was the use of (3-Cyanopropyl)dimethylsilyl(CPDMS)-group instead of TIPS as protecting group at the used OPPE. By using the CPDMS group the alkyne deprotection and dimerisation led to a nearly quantitative conversation of dimerisation reaction.