Invasive plants present a major ecological challenge, but also an opportunity for the sustainable use of biomass. In this master thesis we investigated the goldenrod (Solidago gigantea), one of the most common invasive weeds found in Slovenia, as a source of natural dyes or phytochemicals for the functionalisation of cotton textiles. The main objective was to evaluate the effect of low-pressure gaseous plasma treatment with ammonia on the cotton substrate and the affinity to the dye from the aqueous extract of goldenrod and to compare its effect with chitosan as a bio-mordant. As a reference, silk was also dyed without the plasma pre-treatment, which shows a good affinity for natural dyes due to its natural content of nitrogen functional groups. Cotton samples were treated with plasma at different conditions, and a sample was also pre-treated with chitosan. This was followed by dyeing or functionalisation with goldenrod extract. The highest nitrogen content on the samples’ surface was achieved at the optimum plasma treatment time of 5 min; microscopic images also revealed no fibre damage. The sample treated in this way also had the best depth of staining (K/S = 0.99) and UV protection (UPF = 83.88). The chitosan pre-treatment also improved the colour fastness of the cotton, but not the wash fastness and UV exposure. The results show that ammonia plasma treatment for 5 minutes significantly increases the affinity of the cotton for the goldenrod dye and improves the UV protection properties and UV stability without damaging the fibres. Ammonia plasma treatment thus represents a potential for the development of a sustainable pre-treatment of cellulose for further functionalisation with natural aqueous extracts.
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