A "liquid crystal" is a substance whose properties are intermediate between those of a crystalline solid and an isotropic liquid. The molecules within a liquid crystal are partially ordered, but they are able to translate easily in at least one direction.

In this work, the influence of aromatic structures on drug encapsulation, self-assembly and hydrogel formation was investigated. The physically crosslinked gelling systems were characterized and optimized for the use in biofabrication and applied in initial (bio)printing experiments. Chapter I: The cytocompatible (first in vitro and in vivo studies) amphiphile PMeOx-b-PBzOx-b- PMeOx (A-PBzOx-A) was used for the solubilization of PTX, schizandrin A (SchA), curcumin (CUR), niraparib and HS-173. Chapter II: Compared to the polymers A-PPheOx-A, A-PBzOx-A and A-PBzOzi-A, only the polymer A-PPheOzi-A showed a reversible temperature- and concentration-dependent inverse thermogelation, which is accompanied by a morphology change from long wormlike micelles in the gel to small spherical micelles in solution. The worm formation results from novel interactions between the hydrophilic and hydrophobic aromatic polymer blocks. Changes in the hydrophilic block significantly alter the gel system. Rheological properties can be optimized by concentration and temperature, which is why the hydrogel was used to significantly improve the printability and stability of Alg in a blend system. Chapter III: By extending the side chain of the aromatic hydrophobic block, the inverse thermogelling polymer A-poly(2-phenethyl-2-oxazoline)-A (A-PPhenEtOx-A) is obtained. Rapid gelation upon cooling is achieved by inter-correlating spherical micelles. Based on ideal rheological properties, first cytocompatible bioprinting experiments were performed in combination with Alg. The polymers A- poly(2-benzhydryl-2-oxazoline)-A (A-PBhOx-A) and A-poly(2-benzhydryl-2-oxazine) (A-PBhOzi-A) are characterized by two aromatic benzyl units per hydrophobic repeating unit. Only the polymer A- PBhOzi-A exhibited inverse thermogelling behavior. Merging micelles could be observed by electron microscopy. The system was rheologically characterized and discussed with respect to an application in 3D printing. Chapter IV: The thermogelling POx/POzi system, in particular the block copolymer PMeOx-b- PnPrOzi, was used in different applications in the field of biofabrication. The introduction of maleimide and furan units along the hydrophilic polymer part ensured additional stabilization by Diels-Alder crosslinking after the printing process. / In dieser Arbeit wurde der Einfluss von aromatischen Strukturen auf die Wirkstoffeinkapselung, der Selbstassemblierung und die Hydrogelbildung untersucht. Die physikalisch vernetzten Gele wurden für den Einsatz in der Biofabrikation charakterisiert und optimiert und fanden ersten (Bio)druckversuchen Anwendung. Kapitel I: Das zytokompatible (erste in vitro und in vivo Studien) Amphiphil PMeOx-b-PBzOx-b- PMeOx (A-PBzOx-A) eignet sich hervorragend für die Solubilisierung von PTX, Schizandrin A (SchA), Curcumin (CUR), Niraparib und HS-173. Kapitel II: Ausschließlich das Polymer A-PPheOzi-A zeigt im Vergleich zu den Polymeren A-PPheOx- A, A-PBzOx-A und A-PBzOzi-A eine reversible temperatur- und konzentrationsabhängige inverse Thermogelierung, welche durch eine Morphologie-Änderung von langen wurmartigen Mizellen im Gel zu kleinen sphärischen Mizellen in Lösung begleitet wird. Die Wurmbildung entsteht durch neuartige Wechselwirkungen zwischen den hydrophilen Polymerblöcken und den hydrophoben aromatischen Polymerblöcken. Veränderungen der hydrophilen Blöcke verändert signifikant das Gelsystem. Die rheologischen Eigenschaften können durch Konzentration und Temperatur optimiert werden, weshalb in einem Blendsystem die Druckbarkeit und Stabilität von Alginat signifikant verbessert wurde. Kapitel III: Durch Verlängerung der Seitenkette des aromatischen hydrophoben Blocks erhält man das inverse thermogelierende Polymer A-Poly(2-phenethyl-2-oxazolin)-A (A-PPhenEtOx-A). Die schnelle Gelierung bei Abkühlung wird durch miteinander korrelierende sphärische Mizellen erzielt. Auf Grundlage idealer rheologischer Eigenschaften, konnten erste zytokompatible Biodruckversuche in Kombination mit Alginat durchgeführt werden. Die Polymere A-Poly(2-benzhydryl-2-oxazolin)-A (A- PBhOx-A) und A-Poly(2-benzhydryl-2-oxazine) (A-PBhOzi-A) sind durch zwei aromatische Benzyl- Einheiten pro hydrophober Wiederholungseinheit charakterisiert. Nur das Polymer A-PBhOzi-A zeigt inverses thermogelierendes Verhalten. Durch Elektronenmikroskopie konnten verschmelzende Mizellen beobachtet werden. Das System wurde hinsichtlich einer Anwendung im Bereich des 3D- Drucks rheologisch charakterisiert und diskutiert. Kapitel IV: Das thermogelliernde POx/POzi System, insbesondere das Blockcopolymer PMeOx-b- PnPrOzi, wurde in weiterführenden Studien im Bereich der Biofabrikation genutzt. Durch die Einführung von Maleimide- und Furan-Einheiten entlang des hydrophilen Polymerteil konnte eine zusätzliche Stabilisierung durch Diels-Alder-Vernetzung nach dem Druckprozess realisiert werden.

Unlike vinyl chloride, 1,2-dichloroethylene (DCE) experienced dimerization under free-radical conditions. Chain transfer to DCE by beta-Cl elimination was shown to be the major reason for its nonpolymerization.;During the chlorination of alkyl chlorides with molecular chlorine, the involvement of a bridged intermediate led to the formation of vicinal chlorides as the major products. The yields of geminal chlorides increased significantly in the presence of solvents that form complexes with chlorine atoms, but such solvents also decreased the reactivity of the chlorination. Thus the chlorination of poly(vinyl chloride) (PVC) in the presence of complexing solvents was not a useful method for the synthesis of poly(1,2-dichloroethylene).;Polyacetylene (PA) was prepared by the methods of both Shirakawa and Luttinger. The PA's were chlorinated with Cl2 to form white polymers that were, however, not chlorinated completely, in that double bonds were invariably left in the polymer backbone. The chlorinated PA's had a much higher glass transition temperature than PVC but were much less thermally stable, apparently owing to the presence of allylic chloride groups.;Ring-opening metathesis polymerization (ROMP) followed by addition chlorination with Cl2 provided an approach to the preparation of a series of new polymers that could be interesting technologically. However, experiments with model compounds showed that the addition chlorination of conjugated double bonds or the double bonds of allylic dichlorides is frequently slow and incomplete. The chlorination of ROMP polymers made from cyclopentadiene, 1,3-cyclooctadiene, and 1,3,5-cyclooctatriene also did not proceed to completion, and the chlorination of the -(CH=CHCHClCHCl)n- polymer made from cis-3,4-dichlorocyclobutene did not occur at all.;Polyene sequences formed during the thermal degradation of PVC were found to interact with HCl in order to form an ion pairs whose thermal excitation produces triplet cation diradicals. These diradicals abstract methylene hydrogen atoms from PVC, and the ensuing beta-Cl scission forms internal allylic chloride structural defects that quickly lose HCl. as a result, the autoacceleration of thermal dehydrochlorination occurs.;A "Plasticizer thiol", 2-ethylhexyl 3-mercaptobenzoate, was confirmed to be an excellent thermal stabilizer for PVC and was suggested by preliminary experiments to function via a mechanism involving both the nucleophilic displacement of labile chloride and addition to double bonds.

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