Thiolactone based coupling agents for the synthesis of poly(amide/urethane)s
- Thiolacton basierte Kopplungsreagenzien für die Synthese von Poly(amid/urethanen)
Mommer, Stefan; Möller, Martin (Thesis advisor); Pich, Andrij (Thesis advisor)
Dissertation / PhD Thesis
Dissertation, RWTH Aachen University, 2017
In the present thesis, three different coupling agents are synthesized, which consist each of two cycles: (i) ethylene carbonate - thiolactone, (ii) bis(thiolactone) and (iii) epoxy - thiolactone. The syntheses of each are optimized to give high yields and pure products. Each coupling agent is thoroughly investigated concerning the orthogonal reactivity of its cycles. For the ethylene carbonate thiolactone coupling agent, a one-pot procedure is established where four different building blocks are incorporated into one molecule. Every intermediate in this reaction sequence is isolated and fully characterized. The bis(thiolactone) coupler is again investigated regarding its chemoselectivity towards amines at different temperatures. Then, the bis(thiolactone) is reacted as an AA-type monomer with diamines as BB-type comonomers in a step-growth polymerization. Using two comonomers in different ratios for the polyaddition, thermal properties of the resulting polymers are adjusted. The obtained polymers, which carry thiol groups in the side chain, are functionalized via a simple Michael addition to different substrates. The Michael addition with acrylate functional PEG building blocks gives access to water-soluble polymeric amphiphiles. Regarding the last coupling agent, the reactivity of the cycles is explored towards mono- and dialkylamines. In a one-pot procedure, a four component reaction is carried out using the coupler and three other building blocks. Upon amidation of the thiolactone at low temperatures, an epoxy thiol intermediate is prepared, which undergoes a base-catalyzed thiol-epoxy polyaddition in situ. This polyaddition is put to sound investigations regarding the used catalyst, the catalyst loading, concentration of the monomer, the solvent polarity and the formation of cyclic oligomers. The reaction conditions are optimized to obtain high number average molecular weights and low dispersities. Finally, the use of this coupler for the synthesis of bulk hydrogels is demonstrated. In a second part, this epoxy thiolactone is used for the synthesis of polyelectrolytes. The provided substrates are amino acids and derivatives of such. Upon polyaddition, pH-responsive polyelectrolytes and -ampholytes are obtained. Using two oppositely charged polyelectrolytes, polyelectrolyte complex nanoparticles are synthesized via macromolecular salt formation in solution. The particles are analyzed regarding their size and morphology.