H.-J. Adler

Poly(vinyl alcohol)/poly(acrylic acid) hydrogels: FT-IR spectroscopic characterization of crosslinking reaction and work at transition point

The crosslinking reaction of pure poly(acrylic acid) and its blend with poly(vinyl alcohol) was studied by FT-IR spectroscopy. It is demonstrated that also in blends the anhydride formation characteristic for pure poly(acrylic acid) is the predominant crosslinking reaction upon heating. But the ester formation between poly(vinyl alcohol) and poly(acrylic acid) is detectable due to the ester C=O vibrations and C—O—C vibrations, respectively. The degree of swelling and the Youngs modulus of the crosslinked blend in deionized water depend on the time and temperature of the heat treatment. In dependence of the pH-value of the swelling agent the blends swell or shrink. The working energy at the shrinking or swelling process induced by a change of the pH-value of differently treated blends was measured. The values are in a range of technical interests and comparable with other microactuators.

Trends in polymer chemistry 1998

The research field of “Macromolecular chemistry” has changed considerably during the last 10 years. There has been unexpected break throughs in the area of bulk polymers despite the fact that research in this area could have been considered to be complete. The metallocene catalysts open up the synthesis of new polymer combinations with completely new structures. Their potential has not yet been exhausted. The trend toward building polymeric structures with small dimensions and to nanotechnology is decisive. Many workgroups within germany and abroad have been working on nano-particles and layers and with reactions at interfaces with respect to their technological and biochemical application. Evidently this trend has been promoted though the foundation of competence centers of nanotechnology. The following report for the year 1998 gives some information on these developments without claiming to be complete.

The Mechanism of Initiation of the Anionic Polymerization of Acrylonitrile with 14C-Labeled Lithium Alkoxides in Dimethylformamide

Abstract Investigations of the anionic polymerization of acrylonitrile in dimethylformamide initiated with 14C-labeled lithium tertiary butoxide have shown that the tertiary butoxide group is not incorporated into the polymer chain, Comparison with the initiation behavior of other lithium alkoxides has indicated that the amount of incorporation of the alkoxyl groups from the anionic lithium alkoxide initiators depended on the basicity of the alkoxide group. A new initiation mechanism is proposed which involves as initiator an active center which consists of an electron donor-acceptor complex of the lithium alkoxide with the solvent dimethylformamide and the acrylonitrile monomer.

Trends in polymer chemistry 1997. Part 1 : Pure research

One trend in polymer chemistry apparent over the last few years - that knowledge about known polyreactions has been combined to produce new polymeric architectures - continued in 1997. The greater understanding of metallocenes led to the further development of catalysts and with them to new polymer combinations. Interest is still being shown in hyperbranched polymers and dendrimers. Further interest was shown in the understanding of the structures and properties of interfaces and surfaces, as well as their applications. An overview of news from polymer analysis concludes this part of the report.