Karin Peter

Preparation and application of poly(alkoxytitanate) as a TiO2 precursor with high storage stability

Titanium dioxide is a basic material of our daily life. Because of its favourable properties, such as harmlessness, chemical stability, photocatalytic activity, or whiteness it is increasingly applied in both micro and nano particles and thin films and coating. One of the available procedures for film forming is the sol–gel technology, an inexpensive low temperature process with wide possibilities to vary film properties by changing the composition of the precursor solution or other parameters. In the paper a new precursor polymer for TiO2 film-preparation with high storage and processing stabilities is introduced and applied in thin film forming. The new precursor poly(alkoxytitanate) is prepared by a one step, water-free sol–gel method. A smooth TiO2 film can be prepared using this precursor by spin-coating followed by H2-plasma curing. Comparing to a common precursor such as Ti(O–iPr)4, this precursor has a good solubility in different solvents and a much higher storage stability. The easy to modify precursor end groups enable the tailoring of properties regarding to hydrolysis to both TiO2 particles and films.

Effects of molding surfaces on the wettability of compression-molded polypropene films

Contact angles were measured for a series of compression-molded polypropene films blended with acrylic acid (AA) or maleic anhydride (MAH)/polyethylene oxide (PEO) (1:1) additives. The influence of different molding conditions concerning time and temperature as well as a coating of the aluminium foils used for the processing with polyethylene oxide (PEO) or polyvinyl pyrrolidone (PVP) were investigated. Films processed with uncoated aluminium foils showed, with one exception, no influence on contact angles with increasing molding temperatures and longer processing times. Upon coating the aluminium foils with hydrophilic substances the receding contact angles decrease by up to 60 ° with constant contact angle hysteresis. This behaviour corresponding to a permanent hydrophilization is attributed to chemical reactions of the coating with the functional groups of the additives.