Versuche zur Synthese von [2.2]- und [2.3]Cyclopentadienophanen

Synthetic Attempts towards [2.2]- and [2.3]Cyclopentadienophanes . The first [2.2]Cyclopentadienophane (=2,2,3,3,8,8,9,9-octamethyltricyclo[8.2.1.1^4,7]tetradecatetraene; 1b ) has been synthesized (Scheme 5) by reductive coupling of 6,6-dimethylfulvene 3 → 5 (50%) followed by base-induced twofold condensation of 1,2-di(cyclopentadienyl)-1,2-dimethylbutane 5 with acetone to give difulvene 15 (95%). Reductive coupling of 15 gives a complex mixture of tautomers of 16 , 17 , and 1b , which contains ca. 50% of the target molecule 1b . Other synthetic attempts towards [2.2]cyclopentadienophanes 1a and 1b and [2.3]cyclopentadienophane 18 are discussed.     

Morphology of reactive PP/PS blends with hyperbranched polymers

To study the efficiency of different mechanism for reactive compatibilization of polypropylene/polystyrene (PP/PS) blends main chain or terminal functionalized PP and terminal functionalized PS have been synthesized by different methods. While the in-situ block and graft copolymer formation results in finer phase morphologies compared to the corresponding non-reactive blends, the morphology development in the ternary blend system PP/PS + HBP (hyperbranched polymer) is a very complex process. HBP with carboxylic acid endgroups reacts preferably with the reactive sites of the oxazoline functionalized PS (PS-Ox) and locates mainly within the dispersed PS-Ox phase. A bimodal size distribution of the PS-Ox particles within the oxazoline modified PP (PP-Ox) matrix phase is observed with big PS-Ox particles (containing the HBP as dispersed phase) and small PS-Ox particles similar in size like the unimodal distributed particles in the non-reactive PP-Ox/PS-Ox blends. Factors influencing the morphology are discussed.     

New reactive polymeric systems for use as waveguide materials in integrated optics

Cross-linked polymeric materials are used in a wide range of applications. Special compositions are used in micro-system technologies and its utilization is extending to integrated optics. We have been working for several years in the field of polymers for optical applications. Highly fluorinated polycyanurate systems have been proven as promising waveguide materials in integrated optics. The refractive index can be adjusted reproducibly in a wide range almost continuously. The layer quality was optimized. Low optical losses of less than 0.3 dB/cm@1550nm were obtained and working optical prototypes were developed. The birefringence had been a major problem, but this was solved by adjusting the coefficient of thermal expansion of substrate and film. We will report in this paper on the polycyanurate ester resins and the new triazine containing polymeric systems.     

Investigation of polyelectrolyte adsorption by means of a novel concept based upon the use of model surfaces and model polyelectrolytes

A concept to study the influence of molecular parameters in the adsorption of polyelectrolytes is presented. Characteristic for this approach is the use of model surfaces and model polyelectrolytes. The properties of both the surfaces and polyelectrolytes can be varied in a well defined way and over a broad range. First experiments show that the method is able to give structural information about the adsorbed polyelectrolytes. The method is very sensitive, adsorption experiments with polyelectrolyte concentrations in the region of micromoles per litre are possible.     

Polyelectrolyte-surfactant complexes containing photolabile diazosulfonate chromophores

Low-molar-mass surfactants (S) and polyelectrolytes (PE) containing diazosulfonate chromophores which are photo-labile and electrically charged were used for the formation of polyelectrolyte/surfactant complexes (PESC) in combination with commonly used polyelectrolytes and surfactants. The stable complexes are no longer water-soluble and were characterized by means of nuclear magnetic resonance spectroscopy and in some cases by means of gel-permeation chromatography measurements. Complexes with a 1 : 1 stoichiomctry with respect to charge are formed. Ultraviolet irradiation of the photo-labile PESC resulted in the loss of the ionic interactions.     

Synthesis of halogen-free amino-functionalized polymethyl methacrylate by atom transfer radical polymerization (ATRP)

In order to obtain amino-terminated polymethyl methacrylate (PMMA-NH₂) free of halogen we used the atom transfer radical polymerization (ATRP) to polymerize methyl methacrylate (MMA) in presence of an initiator containing an alkyl bromide unit and a protected amine functional group. The use of CuBr / N,N,N′,N′′,N′′-pentamethyldiethylenetriamine (PMDETA) as co-catalyst system results in a polymer free of halogen due to hydrogen transfer from PMDETA to the growing polymer chain. However, side reactions occur affecting the typically “living” character of the ATRP. The measured molecular weights are consistently higher than the theoretical ones and the molecular weight distributions are relatively broad.