Metal- and Peroxide-Free Silicone Rubbers with Antibacterial Properties Obtained at Room Temperature

Abstract

Metal- and peroxide-free silicone rubbers were obtained via a reaction between amino-containing poly(dimethylsiloxanes) (amino-terminated (APDMS-1) or a copolymer with pendant amino groups (APDMS-2)) and iodine-containing polysiloxanes (PIMSs) (Menshutkin reaction). Simple mixing of functional polymers at room temperature resulted in forming silicone materials. The formation of ammonium cross-links was confirmed using solid-state 1H and 13C NMR spectroscopy. The equimolar ratio of NH2 groups to the I-containing moiety (1:1) was the most optimal among other ratios (2:1 and 1:2) to carry out cross-linking and led to the highest cross-linking density according to the swelling measurements. PIMS/APDMS-1 (1:1) rubbers had the lowest average molecular weight of segments between cross-links Mc = 250 compared to PIMSs/APDMS-1 (1:2) and (2:1) with Mc = 1110 and 390, respectively. The obtained silicone rubbers showed antibacterial activity against Escherichia coli and Staphylococcus aureus and thereby could be applied in biomedicine and the food industry as antibacterial coatings and materials.