Deposition of durable thin silver layers onto polyamides employing a heterogeneous Tollens’ reaction

Tollens’ reaction is a well-known reaction employed in chemical analyses to detect reducing groups—basically aldehydes. If aldehydes are available in a solution these will reduce silver(I) ions to silver(0). The present paper describes an approach to use a heterogeneous Tollens’ reaction to establish thin layers of silver on polyamide surfaces. The polyamide surface is modified with aldehyde functions in a first step employing glutaraldehyde. The resulting polymer material is therefore equipped with reducing groups necessary for the reduction of silver in a next step. The polymer is subsequently treated with Tollens’ reagent yielding a yellow/brownish colour typical for the surface plasmon resonance of silver. The extend of the colouring – indicating the amount of silver deposited – varies with both the concentration of the Tollens’ reagent and the concentration of the glutaraldehyde solution used for the pre-treatment. The as-prepared samples not only show an excellent antimicrobial activity but also an enormous durability. Polyamide textiles that were treated with the described approach showed unchanged efficiency even after 30 laundry cycles.