01/12/2020
2D chromatogram of a reaction mixture from the copolymerization of poly(acrylic acid) (red) and polysaccharide (blue)

2D chromatogram of a reaction mixture from the copolymerization of poly(acrylic acid) (red) and polysaccharide (blue)

Source: BAM, Division Structure Analysis

Polymers based on fossil raw materials are increasingly being replaced by polymers that originate from biological sources and / or are biodegradable. This involves issues of sustainability as well as the disposal and toxicological relevance of these substances.

These polymers are particularly suitable for applications in contact with people e.g. B. in the form of surfactants or as so-called drug delivery systems in pharmacy, but also interesting for applications in the food sector.

So far only a few analytical-chemical methods for characterizing these materials are known. However, knowledge of the microscopic chain structure is of great interest in order to be able to draw conclusions about the extent to which this affects the macroscopic properties of the polymers. Due to the many distributions occurring in polymers, e. g. regarding the molecular weight or functional groups, a separation, especially of copolymer reaction mixtures, is a challenge. For the use of various detection methods, such as mass spectrometry or absorption spectroscopy, a previous separation is mandatory.

For this reason, various liquid chromatographic methods have been developed for the separation of reaction mixtures from the copolymerization of polyacrylic acid and polysaccharides. The reaction creates a graft polymer, which consists of a linear backbone of polysaccharide with randomly distributed branches of polyacrylic acid. The yield of the grafting reaction as well as the microstructure of the copolymer and the two homopolymers were to be determined. Both size exclusion chromatography and adsorption chromatography were used for this purpose. By using various detection methods such as mass spectrometry, absorption spectroscopy, nuclear magnetic resonance and infrared spectroscopy and detecting differences in refractive index, it has been possible to elucidate the microstructure of these polymers in a previously unattained depth of information.

This is the prerequisite for establishing a relationship between the structure and properties of these polymers. In future, polymers with precisely defined properties can be synthesized.

Simultaneous characterization of poly (acrylic acid) and polysaccharide polymers and copolymers
Epping, R., Panne, U., Hiller, W., Gruendling, T., Staal, B., Lang, C., Lamprou, A., Falkenhagen, J.
published in Analytical Science Advances, Vol. 1, issue 1, pages 34 - 45
BAM Division Structure Analysis