Thermally stable and chemically resistant polymer membranes : aromatic polyoxadiazoles and polytriazoles

This thesis concerns the preparation of membranes from thermally stable and chemically resistant polymers. Two polymer families from the category of heterocyclic and aromatic polymers have been selected for investigation, the polyoxadiazoles and the polytriazoles, respectively. A major problem concerning these types of polymers is their bad processability due to their insolubility and infusibility. For the polyoxadiazoles this problem is circumvented by using a two-step preparation process through the preparation of a processable prepolymer membrane followed by a thermal conversion of the prepolymer into the desired polyoxadiazole. For the polytriazoles solubility is acquired by using a phenylated form of a polytriazole backbone

Intramolecular crosslinking of poly(vinyl alcohol)

Poly(vinyl alcohol) is crosslinked in dilute solution (c=0.1 wt%) with glutaraldehyde. The reaction product is characterized by viscometry and gel permeation chromatography (g.p.c.). The intrinsic viscosity decreases with increasing degree of crosslinking and does not depend on temperature. G.p.c. reveals that the reaction product is not homogeneous, but consists of a mixture of particles with different sizes, possibly both intra- and intermolecularly crosslinked molecules. The intramolecularly crosslinked molecules are smaller in size than the initial polymer molecules and their size depends on the degree of crosslinking. They possess a narrow particle size distribution even if the initial polymer sample had a broad molecular weight distribution

Hydrothermal polymerization towards fully biobased polyazomethines

Microwave assisted polycondensation for the synthesis of (partially) biobased polyazomethines in water (hydrothermal polymerization) was investigated for the first time in this study. The polyazomethines preparedviathis environmentally friendly and simple method show comparable characteristics as the polymers preparedviatraditional methods in organic solvents.</p