Cationic Structures Combat Bacteria
Antimicrobial Plastics Based on a New Type of Styrene Monomer
Using a special styrene monomer, it is possible to produce thermoplastics and cross-linked plastics with highly pronounced, intrinsic microbial surface activity. Thanks to their material properties profile, they are suitable for numerous medical device applications.
Preventing and combating microbe growth is an important object in the medical device and food processing sectors. In the 1990s, the intrinsically antimicrobial thermoplastic polymer Poly(TBAEMA) was developed for production on an industrial scale. Unfortunately, the material exhibits a low glass transition temperature, high solubility in polar solvents and high moisture uptake. The Institute of Construction and Functional Material (IKFM) at the University of Applied Sciences in Münster has now picked up the basic principle and developed it further.
The work used a monomer with the designation TBAMS (tert.-butylaminomethylstyrene). The poly(TBAMS) homopolymer produced from it exhibits considerably less moisture uptake than poly(TBAEMA) as well as a glass transition temperature of 68 °C. Through copolymerization it is possible to modify the material properties so that the TBAMS polymers can be compounded with various standard polymers. These compounds can then be processed by means of common methods to produce flat film, blow molded or injection molded parts.
The pronounced antimicrobial activity of the material is based on an electrostatic surface effect. The materials form a hydrophobic surface with a high density of positive charges. The nonpolar, cationic structures damage the cell membranes of the micro organisms so severely that they die off. In addition to thermoplastic materials, a concept has been developed for manufacturing intrinsically antimicrobial thermosets. The resins are suitable for topcoats (gelcoats) as well as the base resin for glass fiber-reinforced plastics (GFP). (hs)